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JAERI-Review—95-019
JP9512215JAERl-Review95-019
JAERI TIARA ANNUAL REPORT 1994 (VOL.4)April 1994-March 1995
October 1 9 9 5
Advanced Radiation Technology Center
Japan Atomic Energy Research Institute2 7 fe 0 7
#- h li.
(T319-11
This report is issued irregularly.
Inquiries about availability of the reports should be addressed to Information Division,
Department of Technical Information, Japan Atomic Energy Research institute, Tc'-ai-
mura, Naka-gun, Ibaraki-ken 319-11, Japan.
©Japan Atomic Energy Research Institute, 1995
¥ii B A< BK i ' 1) OF % m^ li" h £ E|) WJ (ffl
JAERI-Review 95-019
JAERI TIARA Annual Report
1994 (Vol. 4)
April 1994 - March 1995
Advanced Radiation Technology Center
Takasaki Radiation Chemistry Research Establishment
Japan Atomic Energy Research Institute
Watanuki-cho, Takasaki-shi, Gunma-ken
(Received September 21, 1995)
This annual report describes research activities which have been performed
with the JAERI TIARA (Takasaki ton Accelerators for Advanced Radiation
Application) facilities from April 1, 1994 to March 31, 1995.
Summary reports of 86 papers and breaf discriptions on status of TIARA in
the period are contained. A list of publications, the type of research
collaborations and organization of TIARA are also given as appendices.
Keywords : JAERI TIARA, Ion Accelerators, Solid State Physics, Radiation
Effects in Materials, Materials for Space, Semiconductors,
Organic Materials, Inorganic Materials, Nuclear Fusion Reactor,
Functional Materials, Radiation Chemistry, Radiation Biology,
Nuclear Medicine, Biotechnology, Radioisotope Production,
Nuclear Chemistry, Radiation Shielding, Materials Analysis,
Accelerator Technology, Safety Control
Editors : Ryuichi Tanaka, Tadao Seguchi, Isamu Nashiyama, Hiroshi Naramoto,
Hideki Omichi, Akio Toraishi, Hiroshi Watanabe, Hiromasa Watanabe,
Denjiro Nemoto and Sohei Okada
JAREI-Review 95-019
(TIARA)
(1995^9^ 21 H
1) mm*mfc. 2) t f ^ a ^ ^ 3) mmmit¥. 4) %mw. 5) m
JAERl-Review 95-019
Beam Lines for Multiple Beam Irradiation (Target Room 2)
Isotope Separator On-Line (ISOL)
JAERI-Review 95-019
PREFACE
This report covers research and development activities which have beenconducted with TIARA (Takasaki Ion Accelerators for Advanced RadiationApplication) during the period from April 1994 until March 1995, and alsogives an outline of the operation and utilization of TIARA in the sameperiod.
All accelerators of TIARA, i.e. the AVF cyclotron, the 3MV tandemaccelerator, the 3MV single-ended accelerator and the 400kV ion implanter,have been operated satisfactorily through the period, despite the lattertwo accelerators being new instruments after their start of operations forresearch activities in January 1994. This is the first report on R 8 Dactivities under full operation of TIARA.
The Fourth TIARA Research Review Meeting was held on June 28 and 291995 at Tokyo, of which subjects were reported in this issue. 23 oral and44 poster papers, and one invited lecture were presented; 188 personsincluding 113 from outside of JAERI participated the meeting. In contrastwith the earlier meetings, numerous results of TIARA utilization werepresented, suggesting the TIARA is now becoming a fruitfull facility.We owe this to advices of the Consultative Committee for the Research andDevelopment of Advanced Radiation Technology, the Consultative Committee forthe JAERI-Universities Joint Research Project, the TIARA General ProgramCommittee, and their subcommittees.
I sincerely hope the utilization of TIARA will be more prosperous andsuccessful in coming years.
Ryuichi TanakaDirectorAdvanced RadiationTechnology Center,Takasaki Radiation ChemistryResearch Establishment
JAERI-Review 95-019
Contents
1. Semiconductors for Space 1
1.1 Evaluation of Single Event Upsets Induced in RAMs
by Heavy Ion Irradiation 3
1.2 Single-event Current Transient Waveform under Heavy Ion
Irradiation on p+n Junction 5
1.3 Collimation of Heavy Ion Beam Produced by Cyclotron
for Singl-event Measurements 8
1.4 Radiation Effects of Solar Cells for Space Use (II ) 11
1.5 Proton Irradiation Effects of Amorphous Silicon Solar Cell
for Solar Power Satellite( II ) 14
1.6 Study of Ion-beam Induced Luminescence in Semiconductor
Silicon Carbide 17
1.7 Local Control of Electrical Resistivity in Silicon by
High Energy Ion Irradiation 20
1.8 ESR Studies of H+ Ion Irradiated Synthetic Diamond
Crystals 23
2. Biotechnology 25
2.1 Effect of Penetration Controlled Irradiation with
Heavy Ions on Tobacco Pollen 27
2.2 Induced Mutations by Ion Beams in Arabidopsis thaliana 29
2.3 Effects of JAERI Helium Ion Beams on Growth of
Root Tip Cells in Allium cepa 31
2.4 Studies on Induced Mutations by Ion Beam in Plants 34
2.5 Comparative Analysis of Interspecific Hybrids Between
Nicotiana gossei Domin and N. tabacum L., Obtained by
the cross with 4He2+ -irradiated Pollen 37
2.6 Photomorphogenic Mutants of Arabidopsis ( I ) — Isolation of
Mutants Using EMS-treated and Ion Beam-treated Seeds- 40
2.7 Dynamic Observation of Transportation of Water in Plants by
using Positron-emitting Isotope - Effect of Temperature- 42
2.8 RBE/LET Effects of Heavy Ions on Inactivation in
Dry Cells of Deinococcus radiodurans 44
VII
JAERl-Revicw 95-019
2.9 Mechanisms of the DNA Injury by Ion Beams and Its Repair on
Radioresistant Bacteria — Analysis of Mutation Caused by
Ion Beams Using DNA Base Sequence Methods- 47
2.10 Optical Study of Hemoglobin in Red Blood Cells
Irradiated with Ion Beams 49
3. Radiation Chemistry 53
3.1 The Distribution of the Micro Chemical Structural Changes
induced in Polymer by Ion-beam Irradiation 55
3.2 LET Effects of High Energy Ion Beam Irradiation
on Polysilanes 57
3.3 Effect of Radiation Quality on Radical Formation in
Ion-irradiated Solid Alanine 59
3.4 The Ion Beam Radiolysis Using the JAERI-AVF Cyclotron
— The Time Resolved Luminescence Measurement System— 62
3.5 Radiation Effects of Ion Beams on TCNB in PVA Films (II ) 65
3.6 Microdosimetry with Heavy Ions (III ) 68
3.7 Characteristics of Various Film Dosimeters for Ion Beams (in )
- Design and Development of Dosimetry System for
Irradiation of Film Dosimeters- 71
4. Organic Materials 75
4.1 High Energy Ion Irradiation Effects on Polymer
Materials (III ) 77
4.2 Heavy Ion Irradiation Effect on Light Absorption of
Polymer Films 80
4.3 Ion Track Copolymer Membranes Consisting of Diethyleneglycol-
bis-allylcarbonate and Acryloyl-L-proline Metyl Ester 83
5. Inorganic Materials 87
5.1 Low-temperature Electron-irradiation Damage and Recovery
in Boron-doped Graphite 89
5.2 Electron Irradiation Effects on Transport Properties
in EuBazCu30y 90
5.3 Low-temperature Irradiation of Refractory Body Centered
Cubic Metals 91
5.4 Experimental Study on Proton and Helium Ion Irradiation
Damage of C/C Composite 94
5.5 Depth Profile of Damage Structures in Triple-beam
JAERI-Revicw 95-019
Irradiated Austenitic Stainless Steel 96
5.6 Microstructural Evaluation of Single Crystalline A12O3
Irradiated with Triple Ion Beams 99
5.7 Microstructural Studies of Ion-irradiated Ceramic
Materials 102
5.8 Cascade Damage Formation by High Energy Self-ion
Irradiation 104
5.9 Surface Nitridation by Ion Beam Irradiation and
Plasma Processing 107
5.10 Defect Formation in LiF Irradiated with 175MeV 40Ar Ions 109
5.11 Ti Ion Implantation into TiO2 Rutile Single Crystals 112
5.12 Metastable Phase Formation by Ion Implantation (III )
- High Dose Implantation of Silver into Silicon— 114
5.13 Development of High-functional Fullerene Thin Films
by Ion Implantation 115
5.14 Radiation Damages in Synthesized Silica Glasses
Induced by High Energy Fe Ions Irradiation 118
5.15 In-situ Observation of Irradiation-induced Amorphization
in Transmission Electron Microscopy 121
5.16 YBa2Cu30x Films Irradiated by Mn+ Ions 124
5.17 Formation Process of Defect Clusters in MgAlzO< under
Displacive and Ionizing Irradiation 126
6. Materials Analysis 129
6.1 Measurements of Hydrogen Contents in Boron Films Produced
during Decaborane-based Boronization in JT-60U 131
6.2 Development of Elastic Recoil Detection Analysis using
Heavy Ions - Simultaneous Detection of H and He
by Means of ERDA Technique using ' ZC Ions- 134
6.3 Studies on the Processes of Atomic Adsorption and
Desorption at the Solid-Liquid Interface by In-situ
RBS Technique 136
6.4 Study of Charge States of Fast Ions in Single Crystals 138
6.5 High Resolution L X-ray Spectra of Fe by 0.75 MeV/u
H and He Ion Impact 140
6.6 Analysis of Radiation Effect in Nuclear Materials by
PIXE- and RBS-Channeling 142
IX
JAERI-Revicw 95-019
6.7 Effect of Nuclear Force upon Elastic Scattering and Its
Application to Elemental Analysis of H, D and 0 144
6.8 ERDA and RBS using High Energetic Heavy Ions 146
6.9 Stopping and Straggling of ' 5N Ions at 6.4 MeV 148
6.10 On-site Analysis of 5IV+ Implantation into Sapphire
using Dual Beam System 150
6.11 Ion Beam Analysis of Diamond Crystal Implanted with
400 keV39K+ Ions 153
6.12 Analysis of Hydrogen in Nb/Cu Multilayers using Ion Beams 155
6.13 Depth Distribution Analysis of Hydrogen and Deuterium
in Nickel by ERDA 158
6.14 Nuclear Reaction Analysis of Carbon in C-ion Irradiated
GaAs 160
6.15 Study on Mineral Alteration -Analysis of Initial Stages
of Hydrothermal Alteration- 163
6.16 Ion Beams Irradiation Experiments Combined with
Positron Spectroscopy 165
6.17 Observation of the Initial Stage of Laser Ablation 167
6.18 Pulsed Laser Ablation of Silicon : Observation of
Particles Emitted from Si Surface and Sputtering
Phenomena Induced by Laser-ablated Particles 170
6.19 Real Time RHEED Observation during Carbon Thin Film
Growth by Ion Beam Deposition 173
7. Nuclear Chemistry and Radioisotope Production 177
7.1 Synthesis and Biodistribution of Rhenium-186 Labeled HEDP 179
7.2 Identification of the New Isotope 1 2 5Pr and r - R a y
Spectroscopy of the Decay of ' 2 6Pr 181
7.3 A Five-HPGe Detector System for r~r Angular Correlation
Measurement at the TIARA-ISOL 184
7.4 Development of Laser Ion Source for the Study of
Short-lived Isotopes with the TIARA-ISOL 187
7.5 Determination of the Change of Nuclear Charge Radius
in the 81 keV Transition of 133Cs Using •3 3Xe-implanted
Sources 190
8. Radiation Shielding for Accelerator Facilities • : 193
8.1 Radiation Streaming Measurement in a Labyrinth of
JAERI-Rcvicw 95-019
Light Ion Room 2 at TIARA 195
8.2 Measurements of Neutron Spectra from Stopping-length
Targets Bombarded with Light Ions 198
8.3 Study of 7Li(p,n) Source Spectra and Neutron-induced
Charged-particle Emission Cross Sections at TIARA 201
8.4 Measurements of Neutron-induced Activation Cross Sections
at JAERI-Takasaki 204
8.5 Measurements and Analyses on Neutrons Transmitted Through
Iron and Concrete Shields in Intermediate Energy Region 206
9. Accelerator Technology 209
9.1 Development of Visual Beam Adjustment Method for
Cyclotron 211
9.2 Beam Diagnostic Development for the Cyclotron 214
9.3 Present Status and Beam Acceleration Tests on Cyclotron 217
9.4 First Operation of 18-GHz ECR Ion Source 221
9.5 Temperature Increase of Power Cable Assembly Laid in Sleeve
through Shielding Concrete at Cyclotron Facility 223
9.6 Development of High Energy Single Ion Hit System
Combined with Heavy Ion Microbeam Apparatus 226
9.7 2MeV Submicron Microbeam Focusing 229
9.8 Fluence Uniformity Measurement of Two-dimensionally Scanned
Radiation Field of 400kV Ion Implanter 232
9.9 Acceleration of Cluster Ions by 3MV Tandem 234
9.10 Energy Calibration of Single-ended Accelerator 236
9.11 Preliminary Study of Ultra Fine Microbeam (II ) 238
9.12 Development of a High-precision Beam Profile Monitor 240
10. Status of TIARA 1994 243
10.1 Utilization of TIARA Facilities 245
10.2 Operation of AVF Cyclotron 247
10.3 Operation of the Electrostatic Accelerators 248
10.4 Radiation Control and Radioactive Waste Management
in TIARA 249
Appendix 253
Appendix 1. List of Publications 255
Appendix 2. Type of Research Collaborations 263
Appendix 3 . Organization and Personnel of TIARA 264
XI
JAERI-Rcvicw 95-019
1. Semiconductors for Space
1.1 Evaluation of Single Event Upsets Induced in RAMs
by Heavy Ion Irradiation
N.Nemoto, I.Naito, S.Matsuda, H.Itoh, T.Hirao and I.Nashiyama • • • 3
1.2 Single-event Current Transient Waveform under Heavy Ion
Irradiation on p+n Junction
T.Hirao, T.Nisijima, T.Kamiya, T.Suda, S.Matsuda I.Naito,
N.Shiono and I.Nashiyama 5
1.3 Collimation of Heavy Ion Beam Produced by Cyclotron
for Singl-event Measurements
I.Nashiyama, T.Hirao, H.Itoh and T.Ohshima 8
1.4 Radiation Effects of Solar Cells for Space Use (II )
O.Kawasaki, S.Matsuda, Y.Morita, T.Ohshima and I.Nashiyama 11
1.5 Proton Irradiation Effects of Amorphous Silicon Solar Cell
for Solar Power Satellite (II )
Y.Morita, S.Sasaki and A.Ushirokawa 14
1.6 Study of Ion-beam Induced Luminescence in Semiconductor
Silicon Carbide
H.Itoh, T.Ohshima, T.Hirao and I.Nashiyama 17
1.7 Local Control of Electrical Resistivity in Silicon
by High Energy Ion Irradiation
H.Akiyama, K.Honda, M.Yamawaki, M.Yoshikawa, T.Ohshima and
Y.Morita 20
1.8 ESR Studies of H+ Ion Irradiated Synthetic Diamond Crystals
J.Isoya, S.Wakoh, M.Matsumoto, Y.Morita and T.Ohshima 23
— 1 _ _
1. 1
JAERI-Review 95-019
EVALUATION OF SINGLE EVENT UPSETS INDUCED IN RAMsBY HEAVY ION IRRADIATION
Norio NEMOTO*, Ichiro NA1TO*. Sumio MATSUDA*,Hisayoshi ITOH**, Toshio HIRAO**, and Isamu NASHIYAMA**^National Space Development Agency of Japan (NASDA)**Department of Materials Development, JAERI
I. INTRODUCTIONSemiconductor devices, which are
essential parts in artificial satellites andspacecraft, are degraded by radiation inspace. It is well known that theimpingement of high-energy heavy ionson semiconductor devices causes singleevent phenomena like upset and latch up.For space application of memory devicessuch as RAMs, it is important to acquireground data on single event upsets(SEUs) by using accelerators. Theobtained data give useful information onthe reliability of electronic system to beassembled in artificial satellites andspacecraft.
In recent years, the decrease in thecost of spacecraft has been discussed andmuch effort has been made to reduce thecost of missions in space. From thispolicy, it has been a growing interest inthe use of commercial devices inspacecraft. For the success of thisapplication, it is indispensable to test theradiation tolerance of commercial devices.A new single event phenomenon calledmultiple bit upset (MBU) has been foundin highly integrated memory devices.When a heavy ion impinges on atransistor cell, it induces an electricaldisturbance in nearby cells. Thisdisturbance causes simultaneous upsetsof several memory cells, i.e., MBU in amemory device. Because the MBU rateis increased with increasing memory celldensity, attention should be focused onthis phenomenon for space application ofhighly integrated devices.
In this study, we have performed theSEU and MBU tests on several kinds ofmemory devices, by using the AVFcyclotron at JAERI Takasaki.
II. EXPERIMENTAL PROCEDURESThe samples used for the SEU tests
were commercial 16Mbit-DRAMs and4Mbit-SRAMs. To test MBU, we used256kbit-SRAM devices qualified byNASDA for space use and commercial
IMbit-SRAMs. These samples wereirradiated with 120MeV-Ne6+, 260MeV-Ne?+, 330MeV-Ar11+, and 520MeV-Kr20+ from the AVF cyclotron. Particlesemitted from 241Am were also used forour irradiation tests. We measured boththe number of cells in which upsetoccurred due to ion irradiation and thefluence of the ions. From these data wederived the upset rates for each memorydevice under several irradiationconditions. For example, see the flowchart of MBU tests shown in Figure 1.
III. RESULTS AND DISCUSSIONSEU tests of commercial DRAMs
The rate of upsets caused by ionirradiation depends on the linear energytransfer (LET) of the ions insemiconductors[l]. The threshold LETsand the saturated cross-sections obtainedfor the 16Mbit-DRAMs and for the4Mbit-SRAMs are shown in Table 1. Itwas found that the threshold LETs andthe saturated cross sections related to the16Mbit-DRAM were smaller compared tothe 4Mbit-SRAM. This results indicatethat the 16Mbit-DRAMs used in thisexperiment exhibit more radiationsensitivity than 4Mbit-SRAM.
MBU tests of SRAMsThe results of MBU test using
520MeV-Kr20+ ions are shown in Table2. In the table, the number of bit errormeans how many bit errors occurredsimultaneously by the impingement of aheavy ion on a transistor cell. This testwas continued until SEU occurred for100 times. As the irradiation angle wasinclined from the normal direction, theMBU rate and the number of bit errorwere found to be increased. This resultcan be explained by the increase in thesensitive area crossed by a heavy ion andthe increase in the LET of the ion. TheMBU tests on the 256kbit-SRAMs andon the IMbit-SRAMs in which the
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JAERI-Rcview 95-019
density of memory cells is increasedshowed that the MBU rate of the IMbit-SRAMs was higher than that of the256kbit-SRAMs. It was also found thatMBU rate was increased with increasingthe density of memory cells.
IV. SUMMARYIt was found in this experiment that
the commercial 16Mbit-DRAMs exhibit
more radiation sensitivity than 4Mbit-SRAMs. The MBU rate was also foundto be increased with increasing thedensity of memory cells and the ion beamirradiation angle.
REFERENCES1)1. Naito, T.Tamura. H.Itoh et al.,JAERI TIARA Annual Report. Vol. 3(1994)9
\
low rateirradiationf\ error in 1^reading
comparison
several bit error single bit error
near address
MBU
far address
SEU
Table 1 Threshold LET and saturated cross-sectionof 16Mbit-DRAM and 4Mbit-SRAM
Fig. 1 MBU test flow chart4Mbit-SRAM
6Mbit-DARM
6Mbit-OARM
6Mbit-DARM
saturated cross-section(cmVbit)
3.0X10"7
2.56 X1CT8
1.57X10"7
=2X10"8
threshold LET(MeV/(mg/cm2))
1.25
>0.6
>0.6
0.6
irradiation (heavy ion) 520 MeV, LET-34.0M8V/(mg/cm2)
^ " ' ( h e a v y ion) 330 MeV, LET-10.6MeV/(mg/cm2)241 Am («.parade) 5.14 MeV, LET- 0.6MeV/(mg/cm2)
Table 2 Number of MBU (on first sample I second sample)
inclination
number ofbit error
256k-SRAM
1M-SRAM
0 '
2bit
0/3
7/10
3bit
0/0
0/0
4bil
0/0
0/0
33.6"
2bit
1/7
-
3bit
0/0
-
4bit
0/0
-
44.4'
2bit
1
25
3bi(
0
0
4bit
0
0
51.3"
2bit
-
21
3bit
-
9
4bit
-
1
56.2"
2bi(
-
15
3bi!
-
8
4bit
-
1
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JAERI-Review 95-019
1 . 2 Single-Event Current Transient Waveform under Heavy IonIrradiation on p+n Junction.
Toshio HIRAO, Toshiji NISHIJIMA*, Tomihiro KAMIYA, Tamotsu SUDA,Sumio MATSUDA**, Ichiro NAITO**, Noboru SHIONO***, and IsamuNASHIYAMADepartment of Materials Development, JAERI* Electrotechnical Laboratory** National Space Development Agency of Japan*** Reliability Center for Electronic Components of Japan
1. INTRODUCTION
The understanding of charge collectionphenomena under heavy ion irradiation intosemiconductor devices is essential indeveloping single-event hardened integratedcircuits. We have developed a measurementtechnique to observe directly a ultra-fastcurrent transient waveform by combining awide-band digital sampling technique with aheavy-ion microbeam. In the present study,we focus our investigation of the effect ofheavy ion species on the transient waveformand the experimental separation of drift,funnel, and diffusion in current transientphenomena.
2. EXPERIMENTAL METHOD
Specimens used in the experimentswere Si p+n junctions with various substratestructures and junction layouts as shown inTable 1.
In measuring ultra-fast currenttransients, a high speed and wide bandwidthmeasurement circuit was developed, whichconsists of a high speed digital samplingoscilloscope with 50 GHz bandwidth, a widebandwidth (40 GHz) bias tee, coaxial cable,connectors, and a super conducting delayline.
In addition, a bare chip of p+n junctionwas mounted in a chip carrier designed in themicro strip line concept to minimize thedistortion of high speed waveform.
Heavy ions used were 15 MeV carbon(C) ions and 3 MeV Helium (He) ions whichwere generated by ion microbeam equipmentattached to a tandem electrostatic accelerator.The microbeam was about 1 urn in diameterand beam intensity was chosen as low as200-500 ions/sec.
Table 2 shows ranges and LETs of 15MeV C ions and 3 MeV He ions in Si.
3. RESULTS AND DISCUSSION
3.1 Risetime of transient current waveformAround 40 ps risetime was observed in
all the transient waveforms regardless of testsample structures. This fast rise timeobserved is considered to be a verification ofthe bandwidth of the entire measurementsystem. The obtained value of 40 ps risetimerealized in the present measurement systemis one of the fastest risetime ever reported.
3.2 Effect of ion speciesFigure 1 shows the comparison of the
transient current waveforms for 15 MeV Cand 3 MeV He ions irradiation on the Si-EPsample. The waveforms are normalized attheir peak currents. Obviously, chargecollection time in the current transients for Cions is about twice as long as that for Heions. This is the direct experimentalevidence of the theoretical prediction thatlonger charge collection time is needed forheavier ions. The reason of this phenomenonhas not been well understood yet, althoughseveral models have been proposed.
3.3 Separation of current componentsTransient current is known to be
composed of drift, funneling, and diffusioncomponents. We tried to separate these threecomponents experimentally.
3.3.1 Drift and funneling componentsTo separate the effect of drift and
funneling, we applied two different cases ofexperimental conditions by comparing theion range with the depletion width whichvaries with bias voltage negatively applied
- 5 -
JAERI-Review 95-019
across the p+n junction in the low impurityconcentration Si-SSD sample.
The case (a ) is that the ion range islonger than the depletion layer width, and thecase (b) is that the range is shorter than thedepletion layer width. In the former case,both drift and funneling may be observed,while in the latter case only drift may beobserved.
Figure 2 shows the experimentalcomparison of current waveforms for twocases, where the waveforms are normalizedat the peak. It is clearly seen that collectiontime for the case (a) is about twice as long asfor the case (b). This indicates that longercollection time is need for funneling.Considering that funneling is the currentcollection process occurred in the deeperregion than the original depletion layerregion, the result of the present experimentalobservation is reasonable.
3.3.2 Diffusion componentTo separate the effect of diffusion from
drift and funneling, we made currentwaveform measurement by moving theposition of micro-ion beam irradiation acrossthe p+ region in the Si 3-finger sample.
The diffusion current is considered tobecome dominant with the increase in thedistance of irradiation position from thejunction. Figure 3 shows the waveforms forthe irradiations at the center of the p+njunction (RP+ 6|im) and at 3|im away from
the edge of the junction (RP+ 30|im). Thisclearly shows that the peak currentcomponent caused by drift and funnelingdisappears at RP+ 30jim and only the broadwaveform associated with diffusion currentremains. The broad current waveform due todiffusion was observed when the position ofion beam incidence was within about 3 fimaway from the junction edge.
4. SUMMARY
Fast current transient measuring systemis successfully implemented for observingheavy ion induced current in semiconductordevices. Longer collection time is found tobe needed for heavier ion irradiation. Thedifference in current transient waveformamong drift, funneling and diffusion isshown experimentally.
Table 1.
Sample name
Si-SSD
Si-EP
Si-3Finger
Sample list
Doping level
lxl01 4cnT3
lxl01 6cnT3
lxl01 6cnT3
Table 2. Range of LET of He and C ions in Silicon
Ion
Range (urn)
LEKMeV/mg/cm2)
Carbon
ISMeV
14.0
4.13
Helium
3MeV
11.7
0.84
- 6 -
JAERI-Rcview 95-019
1.2
cuuaUo>
|
o
l
0.8
0.6
0.4
0.2
0
-0.20 2.0
15 MeV C-lon: Bias-15VCollected Time:833ps
3 MeV Hc-lon: Bias -15VCollected Time: 1.58ns
8.0 10.0
Fig.
4.0 6.0
Time( ns)
1 Waveforms of Single-event Transient Currents
uu3T3
CD
1.2
1
0.8
0.6
0.4
0.2
0
-0.2
A. 15 MeV C-lon
-
1 Si-SSD
l \ ' ^ Bias-5V\\^*^~**'^ Collected Time 2.5ns 'V*[_ Bias -30V\ \ ^^^-^^Collected Time 1.25ns '.
0 2.0 8.0 10.0
Fig
4.0 6.0
Time (ns)
,2 Bias Dependence of the Transient Currents
c
IU
fo
Times (ns)
Fig. 3 Separation of the Diffusion Component from theDrift and Funneling Component of the Transient Currents
- 7 -
1 . 3
JAERI-Rcview 95-019
Collimation of Heavy Ion Beam Produced by Cyclotron forSingle-Event Measurements
Isamu NASHIYAMA, Toshio HIRAO, Hisayoshi ITOH, and TakeshiOHSHIMADepartment of Materials Development, JAERI
1. INTRODUCTIONAmong various kinds of experimental
studies using swift heavy ions, the mostattractive one is on channeling ion-solidinteractions in crystalline solid. Though ithas not been well investigated yet,channeling effects on Single-Event(SE)phenomena will be an importani factor to beconsidered for an accurate evaluation of theSE tolerance of electronic devices for spaceapplications. Since highly collimated ion-beams are indispensable for channelingexperiments, we have developed a techniqueto collimate heavy ion beams accelerated bythe TIARA cyclotron.
2. EXPERIMENTAL METHODWe used 520MeV Kr2 0 + ion beams
from the AVF cyclotron and two double slitson HE1 and HE2 beam lines for the beamcollimation. Distance between the twodouble slits is 1064cm as shown in Fig.l. Byapplying a 2mm x 2mm aperture to the HE1double slits and a lmm x lmm aperture tothe HE2 double slits, we expect a geomet-rical beam divergence to be 0.017 degree.Experimentally, the beam divergence wasevaluated from the critical angle ofchanneling using thin single crystal samples.Since the beam intensity was not highenough for back-scattering measurements ofchanneling, the transmission method wasperformed, which was good also to avoidserious radiation damage introduced duringmeasurements.
Samples used were a thin single crystalsilicon (Si) wafer with 55um thickness and athin cubic silicon carbide (3C-SiC) film with30 fim thickness. Both samples have the(100) surfaces. The samples were installedon a 3-axes and 1-linear motion goniometerin a vacuum chamber1). Energy spectrum
and fluence of the ion beam after passingthrough the sample were measured with apartially depleted silicon surface barrierdetector (SSD). The highest current of the
collimated beam obtained was 20pA at the'sample position. After the collimation andthe alignment of the beam were completed,intensity of the beam current was attenuatedto be less than 1 fA by a beam degrader forthe transmission channeling measurements.
3. RESULTSFigure 2 shows the energy spectra of
520MeV Kr2 0 + ions after passing throughthe Si sample. A spectrum directly measuredby the SSD without the sample is indicatedby "D", and those for aligned (channeling)and random incidence are indicated by "A"and "R", respectively. From the result, wecan say that channeling phenomenon isobserved using Kr20+ ion beams collimatedby the present slits system. However, foractual transmission channeling experimentsmuch thinner samples are needed in order toreduce the energy straggling.
Figure 3 shows the energy spectra forthe 3C-SiC sample. Since range of 520MeVKJ20+ i o n s j n siC is shorter than the samplethickness in random (off-axis) directions, theboth spectra correspond to the channeledcomponent of the ion beam along the <100>axis of the crystalline 3C-SiC sample. Thedifference of the two spectra shown is mostlydue to the slight change in the incident angleof the beam.
Figure 4 shows a dip-curve for thetransmission channeling of 520MeV Kr20+
ions along the <100> axis in 3C-SiC. Thecritical angle of channeling is obtained to be0.225 degree from the FWHM of the dip-curve. Considering that the theoretical valueof the critical angle for 520MeV Kr20+ ionsin 3C-SiC <100> axis is 0.106 degree atroom temperature, the actual beamdivergence is estimated to be larger than 0.1degree. This value is much larger than thegeometrical value of the beam divergence.Therefore, further improvement of beamcollimation technique is necessary for moreaccurate channeling experiments.
JAERI-Review 95-019
4. SUMMARYUsing a pair of double slits on HE1 and
HE2 beam lines, 520M.eV Kr20+ ions beamswere collimated for channeling experiments.Beam divergence is evaluated by themeasurements of the critical angle for 3C-"•'-C <100> axial channeling, and found to below enough for channeling experiments. Formore accurate channeling measurements,further improvement of beam collimation
techniques is necessary.
REFERENCES1) H. Itoh, T. Hirao, Y. Morita, and I.
Nashiyama, TIARA Annual Report, vol. 1(1992)97.
2) B.R. Appleton and G. Foti, in "Ion BeamHandbook for Material Analysis", Ed.J.W. Mayer and E. Rimini (AcademicPress, New York, 1977), Chap. 3.
No.3 Irradiation room No.4 Irradiation room
vacuum pump vacuum pump
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detector
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Fig 1. Heavy Ion Irradiation Testing Units (Scattering Beam Irradiation Testing Units)
ac3O2"3
500
400 "
300 "
200 -
0 200 400 600 800 1000 1200
Channel Number
Fig. 2 Spectra of Collimation ion beams of 520 MeV -Kr20+
A: Allgencd beamB: Random beamC: Direct beam without silicon sample
- 9 -
JAERI-Review 95-019
800
600 -
2 400
200 -
800
(cou
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600
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200
0
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Channel Number
Fig. 3 Spectra of the 520 MeV Ar 2 0 + beamspassing through single-crystal
c
8
1500
1000
500
520MeV Kr-lon channeling3C-SIC<100>
-4 -1
Angle (degree)
Fig. 4 Dip curve of transmission channeling for30nm thick 3C-SiC<100>
- 1 0 -
JAERl-Rcvicw 95-019
1 • 4 Radiation Effects of Solar Cells for Space Use -11Osamu KAWASAKI*. Sumio MATSUDA*Yousuke M0R1TA**, Takeshi OHSHIMA**, Isamu NASHIYAMA***National Space Development Agency of Japan (NASDA)**Department of Materials Development, JAERI
I . Introduction
Space solar cells are used as electricpower sources for satellite systems. Electricalperformance of solar cells degrades with timebecause of space radiation in the spaceenvironment. Degradation of electricalperformance depends on the kind of radiation,its energy and fluence. When we use solarcells in space, it is important to know theirresistance to irradiation. We have performedirradiation tests using the JAERI AVFcyclotron to investigate radiation effects onsolar cells. Si and GaAs solar cells wereirradiated with protons. In this paper, wedescribe the results of new irradiation tests inwhich we simultaneously irradiate cells withprotons and pseudo-sunlight which isapproximated to Air Mass 0 (AMO) spectrumby using solar simulator. We also present thedegradation dependence of Si solar cells onproton energy based on results from usingthe 3MV tandem accelerator.
II. Experiments
2.1 Solar CellsThe tested samples were silicon solar
cells with a Back Surface Field and Reflectorstructure (Si BSFR) and Gallium Arsenide(GaAs) solar cells which were both qualifiedby NASDA. The Si BSFR solar cells are 2cmX 2cm and 50\im thick. GaAs solar cellsmade by Liquid Phase Epitaxy (LPE) methodare 2cm X 2cm and 200 urn thick. Neithercells have cover glasses.
2.2 Irradiation MethodWe utilized the AVF cyclotron for 10
MeV proton irradiation tests and the 3MVtandem accelerator for lower energy proton
tests. Using the AVF cyclotron, wesimultaneously irradiated cells with protonsand pseudo-sunlight. Figure 1 shows theschematic drawing of the test chamber. Wesoldered probes on electrodes of solar cellsto measure their electrical performanceduring irradiation, and fixed them to a 10cmX 10cm aluminum board with double-sideadhesive tape (Figure 2). We used kaptontape to isolate from the aluminum board. Weadjusted the proton beam shape to about lcmdiameter and scanned the 4cm X 10cmregion. Irradiation test was conducted atintensities of up to 1014 proton/cm2 tosimulate the exposure a satellite wouldreceive in the Van Allen radiation belts. Wemeasured the beam charge in order todetermine ion fluences, which was calculatedby subtracting the secondary electron chargefrom the measured beam charge. Thesecondary electron charge was about 10% ofthe total charge.
We obtained the degradationdependence of Si solar cells on proton energyby using the 3MV tandem accelerator. Theacceleration energies were 1, 2, 3, 5 and6MeV. We adjusted proton beam shape toabout 5mm diameter and scanned the 4cmX 4cm region. Solar cells were fixed to a5cm X 10cm aluminum board with double-side adhesive tape. Electrical performance ofthese solar cells was measured afterirradiation.
11. Test Results
3.1 Simultaneous IrradiationFigure 3 and 4 show the results of
simultaneous irradiating protons and pseudo-sunlight. The Figures show the fluence
- 11 -
JAERI-Rcview 95-019
dependence of normalized electricalperformance for Si and GaAs. Electricalperformance parameters are short circuitcurrent (Isc), open circuit voltage (Voc) andmaximum power (Pmax). As expected, thenormalized electrical performance degradedas fluence increased. However, it wasinteresting to note that the normalized Isc forSi increased as fluence increased from 3 X1013 to 1 x io14 p/cm2, then droppedsuddenly as fluence increased further. Thisnew phenomenon has not been reportedbefore. The phenomenon can not beexplained exactly, but one possible process ofthe increase in normalized Isc is that theexcited carriers which move to theconduction band through the defect levelaccording to multi-photon process. Theincrease in normalized Isc is not observed inGaAs solar cells.
3.2 Degradation Dependence on ProtonEnergy
By comparing fluence at the 75%normalized electrical performances in Si50um solar cells, we obtained the relativedamage coefficients with respect to lOMeVproton(Figure 5). The front surfaces of cellswere irradiated by protons. The relativedamage coefficients increased withdecreasing proton energy because manydefects formed where protons stop. Thisagrees well with data in the JPL Solar CellRadiation Handbook0. For 50jam thick Sisolar cells, protons below 2MeV energy stop
Solar simulator
in the cell. However when irradiated from theback surface, these protons have too littleenergy to reach the PN junction and causelittle degradation damage. Thus, it is difficultto expect degradation of electricalcharacteristics when proton energy is below2MeV.
IV. ConclusionsWe irradiated solar cells with high
fluences as might be received by a satellitewhich remains for a long time in Van Allenradiation belts so that we could clear theelectrical behavior of solar cells. Thenormalized Isc first decreases with increasingradiation fluence, then increases, then finallydrops suddenly as fluence increases. Thenormalized electrical performance of GaAssolar cells differs from that of Si solar cells.The normalized Isc is relatively unaffectedand does not drop suddenly as do the Si solarcells. Further, we obtained degradationdependence of Si solar cells on protonenergy.
AcknowledgmentsWe would like to thank Mr. T.Nakao
and Mr. Y.Wakow of A.E.S. for their usefulsupport and advice.
References1) "Solar Cell Radiation Handbook" H.Y.Tada, Carter Jr., B. E. Anspaugh and R. G.Downing, JPL Publication, Jet PropulsionLaboratory (1982)
Aluminum board
Solar ce
Kapton tape
Fig.l Schematic drawing of test chamber Fig.2 Sample setting
- 1 2 -
JAERI-Rcview 95-019
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Fig.3 Degradation of Si BSFR (50nm) solar cell by lOMeV proton irradiation
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- 1 3 -
JAERI-Revicw 95-019
1 . 5 Proton Irradiation Effects of Amorphous SiliconSolar Cell for Solar Power Satellite!II)
Y. Morita, S.Sasaki1, A. Ushirokawa'-Dep. of Materials Development, JAERI, Institute of Space andAstronautical Science(ISAS), Tokyo Engineering Univ.2
IntroductionThe plan of the Solar Power
Satellite named SPS 20001) is madeas a conceptual design for a 10MWatt scale satellite at ISAS. Itaims to demonstrate the feasibilityof the SPS as an energy system interms of whether it will resolvethe problems of the global en-vironment and energy. For the SPS2000, amorphous silicon(a-Si) solarcell, a thin film type developed forground use, is selected as a poten-tial candidate for its powergenerator, because of convenienceof transportation from ground, andassembly in space.
Amorphous-Si solar cells havenot used before in space, owing totheir photodegradation, and lowconversion efficiency comparedwith those of the crystalline cells.However, as a high conversionefficiency over 10% was achievedin recent development of ihe a-Sisolar cells, the studies of radiationresistance of the a-Si solar cellscomes to be reported for thepurpose of using in space2).
In this report, the radiationresistance of a-Si solar cells, whichis very important problem in therealization of SPS 2000 plan, wasstudied by a simultaneous irradi-ation of 10 MeV proton beam andlight of a solar simulator.
Experimentall:ig. 1 shows a schematic diagram
of the simultaneous irradiationsystem for the a-Si cells. Incidentangles of proton beam and lightbeam(l solar in Air mass 0) of thesolar simulator to the solar cellsamples were right and 40.5degree , respec t ive ly . Theirradiation of proton(10 MeV) tothe solar cells was carried out byscanning the lcm<j> spot beam (80-500nA) in the area of 10x10 cm2.
The electric output power(Pmax=(lxV)max) of the solar cellswas measured by the instrument ofI-V measurement system, which isconnected to the solar cell samples.Fig. 2 shows the schematic diagramof the cross section of a flexible a-Si solar cell(size: 113x120x0.2Sanyo Elec. Co., Ltd.) used in thistest. The a-Si cell was deposited onpoly-ethylene-terephthalate(PET)film (0.05mm thick) by chemicalvapor deposition (CVD) method. Athickness of p-i-n junction of thecell is as very thin as ca. Him.Single crystalline silicon (c-Si)solar cell(size: 20x20x0. lmm 3,Sharp Co., Ltd.) was used asreferences for the a-Si solar cell.
Results and DiscussionFig. 3 shows the relative
retentions of Pmax of the a-Si andthe c-Si solar cells, which wereirradiated simultaneously by 10MeV proton and light from thesolar simulator. The twice irradi-ation tests were performed for a-Sicells and c-Si cells, respectively.The results indicate that the a-Sicells have a higher radiationresistance over 180 times than thec-Si cells. One of the reasons forthe higher resistance could comefrom extremely thin structure ofactive layer(p-i-n junction) in thea-Si cell.
The equivalent damage fluenceduring 1 year for SPS 2000 on the1 100 km equatorial orbit isestimated as 2.L\i0l0protons/cm2
at 10 MeV, which is calculated forcrystalline Si solar cell referringto the Solar Cell Radiation Hand-book by NASA JPL3). The a-Si solarcell tested are degraded typicallyby ca. 1% with the fluence of2xl012proton/cm2 at lOMeV,which corresponds to the total
- 14 -
JAERI-Review 95-019
fluence for the SPS 2000 duringover 100 years. But, if the c-Si solarcell is adopted for the SPS, thefluence(2xl0l 1 protons/cm-) at16% degradation of the Pmax in c-Si cell corresponds to the totalfluence for the SPS 2000 during 10years. However, as high energyprotons pass through the thin a-Sicell, it is necessary for the a-Si cellto be tested by irradiations of lowerenergy protons, which are stoppedin the p-i-n junction of the cell.
Fig. 4 shows the recovery ofPmax of the irradiated a-Si cellsafter storing them at ambient tem-perature. Pmax of the a-Si cells ir-radiated by proton recoveredrapidly immediate after the irradi-ation, and gradually 3-4% of itsretention in the term of 40 days.Total recovery of the Pmax on a-Sicell is 7-8% for each irradiationlevel. In the same irradiation andstoring conditions, Pmax of c-Sicell samples do not recover at all.In c-Si solar cell, degradation of itselectrical proper ty by theirradiation is caused by formationof the various defects in siliconcrystalline. The most of thesedefects arc not annealed atambient temperature region. Onthe other hand, degradation of a-Sisolar cell is caused by formation ofSi dangling bonds which aregenerated by breaking Si-Si andSi-H bonds in a-Si by electronicinteraction between proton andatoms in a-Si. As these danglingbonds react with hydrogengenerated by the irradiation of
PET"4), and migrated in a-Si, it isconsidered that the degradation ofthe Pma.x in the irradiated a-Sisolar cells recover rapidly atambient temperature.
ConclusionThe effects of the high energy
proton(10 MeV) irradiation on thea-Si solar cells which are thepotential candidate for SPS 2000have been investigated by themethod of the simultaneousirradiation of proton beam andlight from the solar simulator. Ithas been found that the a-Si solarcell has a higher radiationresistance than the c-Si cell. And,the electric property of the a-Sicell recovered rapidly immediateafter irradiation at ambienttemperature. From these results,the irradiation effects of the a-Sicell are completely different fromthose of the c-Si cell.
For SPS 2000, it is concludedthat the a-Si solar cells are quitepromising for SPS use if theconversion efficiency and apholodegradation is improved as isnow expected.
References1 )M.Nagatomo and K.lto; 2nd Inter-national Symposium SPS 91, Paris,•91.2)J.J.Hanak el al., 19th IEEE Photo-voltaic Spec-ialists Conference, '87.3)H.Y.Tada et al., Solar Cell Radi-ation Handbook Third Edition,NASA JPL, California, USA, '82.4)T.Sito et al., JAERI-M 89-096('89)
window(synthetic quartz)
solar simulatorAM-meter
incident beam
sample holder
solar cellsample
: Al alloy chamber
I-V Imeasurementsystem
watercoolant
Fig. 1 Schematic drawing of proton irradiation system
- 1 5 -
PET film( front
JAERl-Rcview 95-019
transparentterminal a-Si film(rear)
Fig. 2 Schematic drawing of cross section of flexible a-Si solar cell
100
10K1 10'
Proton fluencc (p/cm2)
Fig. 3 Change in Pmax of solar cells irradiated by 10 MeV protonproton; 1 OMcV, 20~500nA Pmax at 25C
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at ambient temperature,proton; 10 MeV, 6O~5OOnA. Pmax at 25C
- 16 -
JAERl-Review 95-019
1 . 6 STUDY OF ION-BEAM INDUCED LUMINESCENCE IN
SEMICONDUCTOR SILICON CARBIDE
Hisayoshi ITOH, Takeshi OHSHIMA, Toshio HIRAO,and Isamu NASHIYAMADepartment of Materials Development, JAERI
I. INTRODUCTIONThe impingement of high-energy ions
on semiconductors generates dense electron-hole pairs along ion tracks. These electron-hole pairs give rise to single eventphenomena such as soft-error, latch up, andburn-out in semiconductor devices.1-2) Theconcentration of electron-hole pairs inducedby ion irradiation depends on the band gapof semiconductors, i.e., the number ofelectron-hole pairs decreases with increasingthe band gap. Thus, the generation of singleevent phenomena in electronic devices isthought to be suppressed by fabricating thosedevices with wide band-gap semiconductors.
Silicon carbide (SiC), which has a bandgap of =3eV, is considered a superiorcandidate material for electronic devicesused in radiation environment due to itsexcellent electrical and physical properties incomparison with other wide band-gapsemiconductors. In fact, SiC-MOS and MESstructures were reported to have higherradiation tolerance than Si-MOS and MESstructures.3-4) In contrast to the total doseeffects, little is known about single eventeffects on SiC devices. For the application ofSiC to electronic devices in which thegeneration probability of single eventphenomena is reduced significantly, it isimportant to clarify electronic excitation andrelaxation processes occurred in SiC by ionirradiation. In this study, our attention isfocused on radiative recombination ofelectron-hole pairs excited in SiC by high-energy heavy ions. The study of therelaxation processes accompanied withluminescence gives us the information aboutthe density and lifetime of electron-holepairs induced by irradiation. The knowledgeof defects in the material is also obtainedfrom the analysis of luminescence data.
In this paper, we show the results ofion-beam induced luminescence in 3C-SiCand 6H-SiC by 175MeV-Ar8+ ionsaccelerated by the AVF cyclotron. Also, we
discuss the recombination processes ofelectron-hole pairs in these samples.
II. EXPERIMENTAL PROCEDURESSamples used were single crystalline
3C-SiC with *30\im thickness and 6H-SiCwith the thickness of sO.3mm. The 3C-SiCsamples were grown on Si substrates at1400°C by chemical vapor deposition. 5) The6H-SiC samples were grown by modifiedLely method. These samples were mountedon a cryostat holder on a two-axesgoniometer installed in a chamber HE1.Details of the vacuum chamber HE1 havebeen described in a previous paper.6) Thesesamples were irradiated with 175MeV-Ar8+
with the beam current l-3nA. Thetemperature of samples was kept at 50Kduring irradiation. Ion-beam inducedluminescences were obtained by measuringphotons emitted from samples duringirradiation. The transient intensity of emittedphotons and their energy profile wereobserved by a monochromator (Jovin YvonHR250) and a streak camera system(Hamamatsu C1587/C3140), which has adetection region of photon wavelength 200-850nm. Details of the optical measurementsystem were shown in a previous report7). Inthe time-resolved optical measurements, thetrigger signals of the AVF cyclotron and/orthe P-choppcr were used as a trigger signalto start acquiring data.
III. RESULTS AND DISCUSSIONFigures l(a) and l(b) show typical
luminescence spectra induced in 3C-SiCsamples at 50K by 175MeV-Ar8+
irradiation. A broad band at ~700nm and aweak band at s=550nm were observed. Here,the former and latter peaks are labeled Acand Be, respectively. Since the mean iondepth of 175MeV-Ai«+ is =45|xm in SiC,these ions penetrate to the Si substrate undera thin 3C-SiC layer. No significant photon
- 17 -
JAERI-Review 95-019
40000
CHANNELWAVELENGTH (nm) > 735 • 0.276 X CHANNEL
WOO
500
CHANNELWAVELENGTH (ran) . 580 - 0.276 x CHANNEL
Fig. 1 Ion-beam induced luminescence spectra for3C-SiC. The observed wavelength region:(a)735--". >5nm, (b)580-450nm
emission due to ion irradiation was,however, observed for Si samples. Thus, theobserved Ac and Be bands are thought to beemitted from only 3C-SiC
It was reported from photo-luminescence (PL) measurements of asgrown8) and electron irradiated 3C-SiC9)that typical PL lines at emission energiesaround 1.9eV and 2.3eV were observed in3C-SiC. We revealed that PL lines around1.9eV are ascribed to the recombination ofelectron-hole pairs via point defects such asSi vacancies in 3C-SiC.9) PL lines around2.3eV were reported to be due to impuritybound exciton (BE).8) The photon energiesof the Ac and Be bands are approximately1.8eV and 2.3eV, respectively. The photonenergy of Ac is similar to that of the defectrelated PL lines, suggesting that the Ac bandresults from the recombination of carriers viaradiation induced point defects. The energyof the Be band agrees well to that of the PLlines arising from BE. This suggests that theBe band is originated from the carrierrecombination via impurity BE. Phonons areprobably incorporated in theserecombination processes from the fact thatSiC has an indirect energy-band structure.
BOOM
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5 20000
AH
100 400200 300
CHANNELWAVELENGTH (nm) n 635 • 0.276 x CHANNEL
Fig.2 Ion-beam induced luminescence spectrumfor 6H-SiC in the wavelength region 635-495nm.
A typical spectrum of ion inducedluminescence observed in 6H-S1C is shownin Fig.2. In contrast to the photon emissionfrom 3C-SiC, only a broad band labeled AHat =550nm was observed in 6H-SiC. Theshape of this band is similar to that of the Acband in 3C-SiC. Taking account of thedifference in the band gap (=0.5eV) between6H-SiC and 3C-SiC, it is likely that the AHband is attributed to the recombination ofcarriers via radiation induced point defects.Figure 3 shows the time-resolved intensity ofthe AH band during ion irradiation. Theinterval of the obtained signals wasestimated to be 10.2(xs, which is in goodagreement with that of 175MeV-Ar8+ pulses(10.3 (.is) from the AVF cyclotron. Similarresult was obtained for time-resolvedmeasurements of photon emission in 3C-SiC. Taking the time resolution of ourmeasurements into account, the lifetime ofelectron-hole pairs induced in 6H-SiC by Arions is estimated to be shorter than 2^sat
BO000
„ 60000
! 40000
a 20000
0.O0 5.00 10.00 15.00 20.00 25.00 30.00
TIME ((.S)
Fig.3 Time-resolved luminescence-signal inducedin 6H-SiC by Ar ion irradiation.
k sJ w
- 18 -
JAERI-Rcvicw 95-019
50K. It was also found that the intensity ofthe Ac, Be, and An bands decreased with theflucnce of Ar ions. These bands were notobserved apparently after irradiation at dosesabove =1013/cm2. These results can beexplained by the generation of non-radiativerecombination channels in SiC by theirradiation. Further investigations are neededto clarify the recombination processes ofion-irradiation induced carriers in SiC.
IV. SUMMARYWe have performed in-situ optical
measurements at 50K of luminescencesinduced in 3C- and 6H-SiC semiconductorsby nSMcV-Ar8"1" irradiation. Twoluminescence bands were observed around=700nm (Ac) and =550nm (Be) in 3C-SiCsamples. The photon energies of the Ac andBe bands agree lo those of luminescences8-9)via point defects and impurity bound exciton(BE), respectively. Thus, it can be concludedthat the Ac and Be bands arise from thecarrier recombination associated with pointdefects and impurity BE, respectively. Onlya broad band at =550nm (All) was observedin 6H-SiC. This band can be ascribed to theradiative recombination via point defectsfrom an analogy between the shapes of theAH and Ac bands. We obtained the time-rcsolvcd signals of the ion-beam inducedluminescences in SiC samples. The shape ofthe timc-rcsolvcd signals observed in 6H-SiC suggests that the lifetime ol' electron-hole pairs induced by ion irradiation isshorter than 2|.is at 50K. The intensity of
these luminescence bands in SiC sampleswere decreased with fluence of ions. Thiscan be interpreted by the generation of non-radiative defects due to the irradiation.
REFERENCES1) E.L.Petersen, in the Text of Tutorial Short
Course in IEEE 1983 Nuclear and SpaceRadiation Effects Conference, held onJuly 17, 1983, in Gatlinburg, TN, USA.
2) J.C.Pickel, in the Text of Tutorial ShortCourse in IEEE 1983 Nuclear and SpaceRadiation Effects Conference, held onJuly 17, 1983, in Gatlinburg, TN, USA.
3) I.Nashiyama, M.Shinohara, T.Matsumoto,K.Endo, E.Sakuma, S.Misawa,H.Okumura, and S.Yoshida.in Amorphousand Crystalline Silicon Carbide (Springer,Berlin, 1989) p. 123.
4) M.Yoshikawa, H.Itoh, Y.Morita,I.Nashiyama, S.Misawa, H.Okumura, andS.Yoshida, J. Appl. Phys. 70 (1991) 1309.
5) S.Yoshida, K.Endo, E.Sakuma, S.Misawa,H.Okumura, H.Daimon, E.Muneyama,and M.Yamanaka, Mat. Res. Symp. Proc.97(1987)259.
6) H.Itoh, T.Hirao, Y.Morita, I.Nashiyama,TIARA Annual Report, 1(1992) 97.
7) H.Itoh, T.Hirao, I.Nashiyama, TIARAAnnual Report, 2 (1992) 134.
8) W.J.Choyke, Z.C.Feng, and J.A.PowellJ. Appl. Phys. 64 (1988) 3163.
9) H.Itoh, M.Yoshikawa, I.Nashiyama,H.Okumura, S.Misawa, and S.Yoshida,J. Appl. Phys. 77 (1995) 837.
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JAERI-Revicw 95-019
1 . 7
Introduction
Local Control of Electrical Resistivityin Silicon by High Energy Ion Irradiation
II. Akivama, K. Honda, M. YamawakiM. Yoshikawa1, T. Ohshima^, Y. Morita*
Mitsubishi Electric Co. Ltd.,Dep. of Materials Development, JAERI, Takasaki^
High energy ion irradiation insilicon power devices, such aspower thyristors, has been studiedfor improving their characteris-tics into higher frequency andlower power loss drives^). Deeplevel defects in the band gap ofsilicon introduced by ionizingradiation or charged particles actas recombination centers ofelectrons and holes to reduce alifetime of carriers in thesemiconductor, and these defectsare, consequently, useful tocontrol the lifetime of carriers inthe devices. Especially, when ionirradiation technique is used tothis application, it is possible toobtain the various performancesof the lifetime control for highspeed drive on the devices, becauselocalized defects around the meanion depth in silicon are introduced,and control the lifetime of carriersaround the narrow specified areaof the devices.
In this paper, we discuss thefollowings:(l)Effects of ion irradiation usedmetal mask for thyristor (ex-periment and simulation)(2)Annihilation phenomena ofsilicon defects by heat annealingprocess.
Ion irradiation for ihyrislor
Ion irradiation method usedwith metal mask (mask irradiation)is effective to low power loss drivefor middle power device, such asinsulated gate bipolar transistor(IGBT)2). The thyristor sample ofIGBT(Mitsubishi Co. Ltd.,) wereirradiated by 70x70mm2 scanningbeam of He2+(20McV) ion usingAVF cyclotron at JAERI Takasaki.
The irradiations were carried outon both side of the thyristor byusing stainless steel metal maskwhich has the thickness of 50(xmfor IIe2+ 20MeV for ions not to passthrough the mask, and has holeswith diameter of 140 ^m.
Figure 1 shows schematicdrawing of the most dense defectarea, produced by ion irradiation,in a cross section of the thyristorwith the mask irradiation and airradiation without the mask(conventional irradiation). In themask irradiation, the dense defectarea, corresponding to the lifetimecontrol area, distributes in N-region according to mask pattern.Figure 2 shows the relationshipbetween on-state voltage of thethyristor and fluences of He2+. Theon-state voltages in the maskirradiation are about 1/6-th lowerthan that in the conventionalirradiation.
Figure 3 shows the relationshipbetween on-state voltage of thethyristor and turn-off time, whichwas calculated by device simula-tion. The turn-off limes in themask irradiation arc shorter thanthose in the conventional irradia-tion. In the mask irradiation of thethyristor, the turn-off times canbe reduced to 69%, compared withthose in the conventional irradia-tion at the same on-stage voltage(1.4V). From these results, theeffects of the mask irradiation ofHe2+ to IGBT were obtained.
Annihilation phenomena ofsilicon defects by heat annealingprocess.
To apply the lifetime controltechnique to actual device process,it is important to know the effect
- 2 0 -
JAERI-Review 95-019
of heat annealing on a irradiateddevice.
Figure 4 shows the relationshipbetween the on-state voltages andannealing time of 350C. In thiscase, the sample devices arc middlepower diode, and the irradiationcondition is as follow:H+,1.5MeV;fluences, l x l0 n ~ lx l0 1 3 p/cm2
(tandem accelerator). When theannealing time is shorter than onehour, the on-state voltagesdecrease rapidly. Figure 5 showsDI.TS(Deep Level TransientSpectroscopy) spectra of the irra-diated diode and the annealedsamples. The irradiated diode hast h r e e large peaks whichcorrespond to defects in silicon,though these peaks should beanalyzed by multiple fitting
method because they are broad,and do not seem a single peak. Byannealing of one hour, the peaksdisappear except that of /Vccntcr(complex defects of vacancy andoxygen impurity). As a defect insilicon induced by low energy H+
is different from that by highenergy IIe2+, we carry out the heatannealing to the thyristor sampleswhich are irradiated by \\e~+ ions.
In further, we also plan to studythe effect of irradiation of highenergy heavy ions for these powerdevices.
References1 )T.Nakagawa et al., Proc. of ISPSD'95,pp.84-88(1995).2)II.Akiyama et al., proc. of ISPSD•91,pp.l87-19l(1991).
N +;
j /
/ /
Ir
P
Lifetime control area
Cathode
Metal mask
Fig. 1
Anode
He2+ H e 2 +(20MeV) (20MeV)
Conventional irradiation Mask irradiationSchematic drawing of irradiated thyristor(Cross section)
15
10
S6
O Conventional irradiation /
• Mask irradiation ,'
10* - v l O - v l l1O'U 1 0 " 10
Irradiation dose (cm-2)
12
:ig. 2 Relationship between on-state voltage of thyristor and fluence ofIrradiation: He2+,20MeV
- 21 -
JAERI-Review 95-019
10
•Io
jj0.1
High speed,: and low loss drive
O Conveniioiuil uiaduilionD Mask irradiation
0 0.5 1 1.5 2 2.5 3 3.5 4
On-state voltage (v)
Fig. 3 Relationship between on-state voltage of thyristor and turn-off time.(Simulation)
4.0-
2 3.0 H
2.0-
1.0-
o
Q.0-
— • — lE13p/cm2
- - A - lE12p/cm2
—-O—• lEllp/cm2
Annealing temp. 3 5 0 "C
Rg. 4
0.0 2.0 4.0 6.0 8.0 10.0
Annealing time ( h r )Effect of heat annealing for ion-irradiated diodeIrradiation: H+,1.5MeV
c0)
c"53
18
14
10
- 2
Before annealing- lh annealing
•••• 8h annealing
Annealing conditiont : , N2
A-center
j i i L
Fig. 5
0 50 100 150 200 250 300 350Temperature ( K )
DLTS spectra of ion-irradiated and annealed diodesIrradiation: H+,1.5MeV
- 2 2 -
JAERI-Rcvicw 95-019
1 . 8 ESR Studies of H+ Ion Irradiated Synthetic Diamond Crystals
J. Isoya, S. Wakoh, M. Matsumoto, Y. Morita and T. OshimaUniversity of Library and Information Science and *Takasaki Radiation Chemistry Research Establishment, JAERI
1. Introduction
Diamond is a promising material for appli-cations to electronic or optical devices whichare used in a harsh environment. Although rel-atively large synthetic diamond crystals ofhigh-quality are now available as a result ofrecent developments in high-pressure synthe-sis, incorporation of dispersed impurities at thegrowth stage is so far limited to only a few el-ements (N, B, Ni, Si). While p-type semicon-ducting crystals are easily obtainable by incor-porating boron, growth of n-type crystals hasnot been established yet. To develop applica-tions of diamond to electronic and optical de-vices, incorporation of new impurities whichcreate useful properties such as n-type semi-conducting crystals is required. Since dopingby thermal diffusion does not seem feasible,ion implantation is a potential candidate forintroducing new impurities into diamond.However, impurities which are implanted maynot necessarily be incorporated as isolatedsubstitutional impurities. Moreover, latticedamages are created by the irradiation. Inour project, we identify local structure of im-planted ions and that of implantation-induceddefects by using electron spin resonance(ESR) technique which is powerful in obtain-ing detailed structural information of point de-fects. The purpose of our study is to clarify theproblems of utilizing ion-implantation methodsuccessfully for incorporating impurities intodiamond. We started with high energy H ionimplantation of synthetic diamond crystals.
2 Experimental
Diamond crystals are classified into four
types, type-la, Ib, Ha, and lib, by the concen-tration and the form of nitrogen impurities.Boron-doped crystals belong to type lib.Various synthetic crystals, in which both thekind(s) and the concentration of impurities (N,B, Ni) were systematically varied by varyingthe composition of the metal solvent, weregrown at 6 GPa and at 1700 K by temperaturegradient method. For the H+ implantation,synthetic diamond crystals were bombardedwith H+ ions (10 MeV,) from an AVF cyclo-tron at room temperature. By accumulatingthe fluence by repeating the irradiations, thefluence dependence has been studied in therange form 1 x 1015 to 1 x 1017 H+/cm2. TheESR measurements were performed on aBruker ESP300 X-band spectrometer by usingan Oxford Instrument ESR-900 to control thesample temperature.
3. Results
The following results which were obtainedfrom the experiments with the fluence 1~7 x10 H+/cm2 have been confirmed by thosewith increasing the fluence up to 1 x 10H+/cm2: (1) After H+-implantation, ESR sig-nals which are arising from isolated vacancies,vacancy-complexes, and vacancy-impurity-complexes were observed. The kinds of im-plantation-induced defects strongly depend onthe impurities (the kind and the concentration)incorporated at the growth stage. In type-libcrystals, the kinds of implantation-induced de-fects are different from those produced by 2MeV electron irradiation. (2) The ESR signalsof amorphous carbon was not observed. (3)The increase of the ESR signals of the implan-tation-induced defects with the increase of the
- 23 -
JAERI-Rcvicw 95-019
fluence indicates a tendency of saturation athigher fluences.
It is estimated that 10 Mev H+ implanta-tion has a mean depth of ~400|J.m with a half-width of several nm. Although the distributionof implanted H+ ions in the crystals is likely tobe highly non-uniform, the accumulation offluence up to lx 10 H /cm reaches to anaverage concentration of [H]=5.7 ppm for aplate-shaped crystal with a thickness of 1 mm.Even for the high fluence, so far, no ESR sig-nals that exhibit hydrogen hyperfine interac-tion have been found for the crystals whichwere kept at room temperature after H+ im-plantation, by using ordinary cw-ESR tech-nique. It is likely that hydrogen implanted ex-ists mosdy in a non-paramagnetic form.Experiments which extract a weak hydrogenhyperfine interaction which might be hiddenunderneath the linebroadening by using pulsedESR technique as well as the ESR measure-ments under light illumination at low tempera-ture and the thermal annealing experiments toelevated temperatures are currently being car-ried out.
Our project is now extended to implanta-tion of ions such as phosphorus ions whichmight create n-type semiconductors.
4. Acknowledgments
The synthetic diamond crystals used in thepresent work were grown by Dr. H. Kanda(NIRIM).
5. Publication
J. Isoya, H. Kanda, and Y. Morita,"ESR Studies of Point Defects in SyntheticDiamond Crystals",Advances in New Diamond Science andTechnology (Proceedings of the FourthInternational Conference on New DiamondScience and Technology),edited by S. Saito et al., (Myu, Tokyo, 1994)pp.351-354.
7 x 1 0 1 6 c m - 2
•t-V
1 x 101 7cm-2
B // [110], 20K, 1 raw5200 UO0 3340 3360 3360 3400 3420 3440 3460
Fig.l ESR spectra of H+implanted type-Ibsynthetic diamond crystalsThe signal intensity of the A1 center, and thatof negatively charged vacancy exhibits a ten-dency of saturation at higher fluences. Thesignal intensity of nitrogen and that of nickelimpurities (substitutional, interstitial) de-creased with the increase of the fluence.
•*• Af\ ^-^J\jA^^
3260 3280 1300 3320
295K, 0.2 tnW2500 3000 JSOO
(el
Fig.2 ESR spectra of H + implanted type-IIasynthetic diamond crystals
(5xl016H+/cm2,B//[110])The Al, and Rl spectra, and some unknownspectra were observed.
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JAERl-Review 95-019
2. Biotechnology
2.1 Effect of Penetration Controlled Irradiation with
Heavy Ions on Tobacco Pollen
A.Tanaka, T.Yamashita, T.Shimizu, M.Kikuchi, Y.Kobayashi
and H.Watanabe 27
2.2 Induced Mutations by Ion Beams in Arabidopsis thaliana
A.Tanaka, Y.Yokota, N.Shikazono, H.Watanabe and S.Tano 29
2.3 Effects of JAERI Helium Ion Beams on Growth of
Root Tip Cells in Allium cepa
H.Ohara, N.Inomata, T.Kurono, M.Miyachi, T.Yamada,
H.Watanabe, Y.Kobayashi, M.Kikuchi and A.Tanaka 31
2.4 Studies on Induced Mutations by Ion Beam in Plants
H.Nakai, H.Watanabe, S.Kitayama, A.Tanaka, Y.Kobayashi,
T.Takahashi, T.Asai and T.Imada 34
2.5 Comparative Analysis of Interspecific Hybrids between
Nicotiana gossei Domin and N.tabacum L, Obtained by
the cross with 4He2+ -irradiated Pollen
T.Yamashita, M.Inoue, H.Watanabe, A.Tanaka and S.Tano 37
2.6 Photomorphogenic Mutants of Arabidopsis ( I )
- Isolation of Mutants Using EMS-treated and
Ion Beam-treated Seeds -
H.Ichikawa, A.Tanaka and S.Tano 40
2.7 Dynamic Observation of Transportation of Water in Plants by
Using Positron-emitting Isotope - Effect of Temperature-
T.Fujimura, K.Adachi, H.Ohmichi, H.Matsuoka, N.Shigeta,
T.Sekine, H.Uchida, T.Yamashita, K.Omasa, M.Takoi and
H.Kobayashi 42
2.8 RBE/LET Effects of Heavy Ions on Inactivation in
Dry Cells of Deinococcus radiodurans
Y.Kobayashi, T.Shimizu, A.Tanaka, M.Kikuchi, G.Taucher-Scholz
and H.Watanabe 44
2.9 Mechanisms of the DNA Injury by Ion Beams and Its Repair on
Radioresistant Bacteria - Analysis of Mutation Caused by
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JAERI-Review 95-019
Ion Beams Using DNA Base Sequence Methods —
K.Harada, T.Nakano, Y.Obiya, H.Watiinabe, Y.Kobayashi,
A.Tanaka and M.Kikuchi 47
2.10 Optical Study of Hemoglobin in Red Blood Cells
Irradiated with Ion Beams
K.Adachi, T.Fujimura, H.Ohmichi, H.Watanabe, M.Takoi,
M.Fukawa, H.Kobayashi and M.Tamura 49
- 2 6 -
JAERI-Review 95-019
2 . 1 Effect of Penetration Controlled Irradiation with Heavyions on Tobacco Pollen
Atsushi Tanaka, Takao Yamashita*, Takashi Shimizu, MasahiroKikuchi, Yasuhiko Kobayashi and Hiroshi WatanabeDepartment of Radiation Research for Environment andResources, JAERI,* Department of Agriculture, KyotoPrefectural University
IntroductionThe characteristics of ion beams are
readily to be controlled the range in targetmaterial and easily to be focused on a target.Taking advantages of these characteristics,we are directing the work toward the devel-opment of the "cell-surgery" techniquethrough the irradiation due to localized en-ergy deposition of heavy ions onto the cell.However, the effects of the local irradiationon the cell is not still clear.
Until now, with the use of IrradiationApparatus for Cell (IAC), connected to abeam line of 3 MV tandem accelerator, wedemonstrated that the ion range in a targetcould be controlled by changing the distancefrom beam window to the target1) (Fig. 1).In this study, we investigated the effects ofthe penetration controlled irradiation ontobacco pollen as a model cell system for thelocal irradiation. From the results, highfrequency of the "leaky pollen", presumablycaused by cell membrane damages, wasobserved at the end of the range of the ions.
30
3.a 20
f 15o
jo
~ 10BO
6McVHe
10 15 • 20 25 30 35 40Distance from beam window (mm)
Fig. 1 The ranges in biological material of 6 MeVHe ions and 18 MeV C ions as a function of thedistance from beam window. Ion beam fluencedecreases from around dotted line to the end of therange (solid line).
Results and DiscussionWhen the heavy ion-irradiated dry pollen
(20 fim) was stained with aceto-carmirje,what is called, "leaky pollen" (Fig. 2) wasfound2). The internal substance leakedthrough an opening of outer membrane of tli^pollen grain. Leaky pollen has never beenfound in the gamma-rays irradiation2).Leaky pollen seemed to be a result of physi-cal lesion induced in outer membrane of thepollen by heavy ions.
Fig. 2 A typical" leaky pollen"
Fig. 3 shows the effects of He and Cions on the leaky pollen frequency at a cer-tain distance from beam window. The fre-quency of the leaky pollen increased linearlywith the ion fluence in both cases of He andC ions. However, C ions were more effec-tive than He ions. The LET at the cell sur-face is about 180 keV///m with He ions, and800 keV//an with C ions, respectively.Schon et al.3) showed that the hemolysis ofhuman erythrocytes, as a parameter for mem-brane damage, was induced more efficientlywith higher LET values (92-14,000keW/rni). Therefore, the difference of theleaky pollen frequency found in between Heand C ions may be attributable to LET value,even though further investigations usingheavy ions with different LET are neces-sary.
- 27 -
JAERI-Rcview 95-019
o C ions• He ions
10 15 20 25 30
Fluencc(XlOI0p/cm2)
35 40
Fig. 3 Leaky pollen frequency as a function of ionbeam fluence. Pollen were irradiated at a distance of5 mm from beam window for C ions, and of 30 mmfrom beam window for He ions, respectively.
Monolayered dry pollen, sandwichedbetween kapton films (7.5 ftm thickness),were irradiated with He ions by changing thedistance from beam window (Fig. 4). Theleaky pollen frequency decreased with in-creasing distance from beam window (12-27mm). Moreover, one major peak of leakypollen frequency was obtained at a distanceof around 30 mm. At this distance, consid-ering the thickness of kapton film, the rangeof the ions in a pollen will reach at 2-3 fim,and the energy of He ions is estimated at-150 keV/u. Similar result was obtained incase of C ions at a distance of around 13 mm(Fig. 5), where the range of ions was about4 ^m, and the estimated energy was -330keV/u (in case of C ions, monolayered pol-lens were not sandwiched by kapton film).No distinct Bragg peak for C ions, but abouttwo-fold peak for He ions were found in en-ergy loss curves near the end of the rangefrom the estimation. It is thought that lowenergy is only deposited locally on a nearbycell surface by these stopping particles.Therefore, these results may indicate thatefficient cell membrane damages, whichcould not be accounted for by conventionalenergy deposition, would be induced by thestopping particles. Schneider et al.4) showedthat inactivation cross sections for yeast aswell as for bacterial spores increased to 10-30% in total at the end of the range of theions. The authors also suggested that at thevery end of the range of the particles, i.e. atparticle energies of around 100 keV/u, otherinteractions than electronic stopping mightplay a more important role. Leaky pollen,presumably caused by membrane damage, isdifferent from another biological endpointsuch as cell inactivation that was thought to
be caused by the DNA damages. However,our findings that high leaky pollen frequencywere induced at the end of the range of ions,will also indicate the characteristic effects ofthe stopping particles on the cellular systems.
15 20 25 30Distance from beam window (mm)
0Control
Fig. 4 Leaky pollen frequency after irradiation withHe ions at 4xlO10 ions/cm2 as a function of distancefrom beam window.
7 9 11 13 15 17 ControlDistance from beam window (mm)
Fig. 5 Leaky pollen frequency after irradiation withC ions at 9xlO9 ions/cm2 as a function of distancefrom beam window.
References(1) A. Tanaka, T. Shimizu, M. Kikuchi, Y.
Kobayashi and H.Watanabe, TIARAAnn. Report 3: 27-29 (1994)
(2) M. Inoue, H. Watanabe, A. Tanaka andA. Nakamura, TIARA Ann. Report 2:50-53 (1993)
(3) W. Schon, C. Ziegler, H. Gartner andG. Kraft, Radiat. Environ. Biophys. 33:233-241 (1994)
(4) E. Schneider, M. Kost and M. Schafer,Radiation Protection Dosimetry 31(1/4):291-295 (1990)
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JAERI-Revicw 95-019
2 . 2 Induced Mutations by Ion Beams in Arabidopsis thaliana
Atsushi Tanaka, Yukihiko Yokota*, Naoya Shikazono, HiroshiWatanabe and Shigemitsu TanoAdvanced Sci. Res. Center at Takasaki, JAERI. * Beam OperationCo.
IntroductionIon beams with high LET are expected
to induce the large structural changes at DNAlevel in living cells, because of localized de-position of large amount of energy.
Until now, studies on induced mutationrate by ion beams were mainly done by usingcultured mammalian cells and microorgan-isms1), but the characteristics of induction ofmutation have not yet been made clear.However, it has been suggested that the ionbeams could preferentially induce the chro-mosomal aberrations in human cells2) and therare mutations which were not obtained byordinary low LET radiations in plants3).Therefore, the mutations induced by ionbeams may be different qualitatively from thelow LET radiations.
In order to make clear the characteristicsof mutations induced by ion beams, we areproceeding the work in respect to the follow-ing objectives by using Arabidopsis thaliana :(1) Analysis of the mutation spectrum atplant level, and (2) of structural changes in-duced by ion beams at DNA level by usingknown mutated gene loci. Special attentionsare focused to find the non-existed new typeof mutants which have characteristics of ionbeam irradiation.
Results and Discussion1. Induced mutation spectrum
Induced mutations derived from theseeds irradiated with 100 and 200 Gy of Cions (18.3 MeV/u), and electrons (2 MeV,500 and 1,000 Gy) as a control, were com-pared. As shown in the previous report4),irradiations with 200 Gy of C ions and 1,000Gy of electrons were semi-lethal to survival,i.e. "shoulder end" in survival curves.Induced mutants were classified to 7categories and expressed as a number oflines having mutants at M2 generationderived from self pollinated plants after ir-radiation (Table 1). From the results, dwarfmutants were induced at high frequency afterirradiation with 200 Gy of C ions. In thecase of chlorophyll mutation, 100 Gy of Cions induced the mutant at higher frequencycompared to electrons, but its frequency de-creased at 200 Gy. This tendency suggeststhat the specific effects of ion beams anddose dependency are existed. We would liketo make clear the specific characters of ionbeams with respect to the specified mutantcharacters by increasing number of testinglines.
2. The mutants at the known loci and thenew specific mutants induced by ion beams
In order to analyze the characteristics of
Table 1 Mutation spectrum induced by C ions and electrons
No. of lines with mutated character
Radiat. Dose(Gy)
Cotyledon, Leaf Flower, Stem SeedsTotal
Color Morph. , . " Dwarf Others Steriler chome stage
No. of Mutat.tested ratelines (%)
electron
Cions
500
1,000
100
200
3
8
7
5
7
6
1
5
1
0
0
0
4
6
0
4
3
3
2
10
1
1
0
2
6
7
2
4
25
31
12
30
63
63
96
73
40
49
13
41
- 2 9 -
JAERI-Review 95-019
\
Fig. 1 Seed color: left, wild type; right, tt mutantinduced with C ions.
Fig. 2 Trichomes: left, wild type; right, trichome-less (glabra) mutant induced with C ions.
Fig. 3 Pigment deposition in immaturedseed coat 4 days after fertilization : left,wild type; right, C ion induced mutant.
the induced mutants with ion beams at DNAlevel, the induced mutant should be com-pared with the known mutants induced al-ready with chemicals or X-rays. From thatreason, the mutants at transparent testa locus(tt) which base sequences have been ana-lyzed, and trichomclcss (glabra) mutantshave extensively been tried to induce withion beams. Until now, several lines of tt(Fig. 1) and glabra (Fig. 2) mutants wereobtained. During the selection process of theabove mentioned mutants, several interestingmutants which has not yet been reportedwere obtained. Among those mutants, seedcoat pigmented mutant which accumulatereddish brown pigment scattering in the seedcoat at early developmental stage after fertil-ization (Fig. 3) and the mutant which showschlorophyll deficient only at the growing partof the plant, were obtained.
Mapping of the genetic loci on the chromo-somes and the analysis of DNA at molecularlevel arc in progress.
References(1) J. Kicfcr, Radiat. Environ. Biophys.
31:279-288(1992)
(2) R. Cox and W. K. Masson, Nature276: 629-630 (1978)
(3) Z. Liu, Q. Qiu, W. Huang, M. Mci andT. Yang, J. Radiat. Res. Radiat. Process9:139-144 (1991)
(4) A. Janaka, Y. Yokota, H. Watanabe, N.Shikazono and S. Tano,TIARA Ann.Report 3: 32-34 (1993)
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JAERI-Rcvicw 95-019
2 . 3 Effects of JAERI Helium Ion Beams on Growth of
Root Tip Cells in Allium cepa
Hiroshi Ohara1, Nobumichi Inomata*, Takeshi Kurono1, Midori Miyachi1 ,Takaharu Yamada1, Hirishi Watanabe3, Yasuhiko Kobayashi3,Masahiro Kikuchi3 and Atsushi Tanaka3
'Faculty of Science, Depertment of Biology, Okayama University2 Faculty of Agriculture, Depertment of Biotechnology, Okayama University3 Depertment of Radiation Research for Environment and Resources, JAERI
1. Introduction
Main purpose of this study is to recognize a
biological action of high energy deposition in
localized sites within a living cells, which were
irradiated by those of particle radiation like
helium « -particle beams that can be produced
by JAERI AVF cyclotron. The cellular radiation
injuries have been featured by induction of
molecular and structural change in the most
critical target, DNA. The radiation induced
molecular damage in terms of single and
double strand breaks of DNA are also
recognized to correlate quantitatively and
qualitatively with biological effects. The
radiation induced chromosome aberrations are
apparently considered to be a base of
mutations and cell killing as well as cancer
induction in case animal cells. The formation of
chromosome aberrations may be though to
indicate the nature of initial damage and its
development. The question whether difference
in biological effectiveness between high- and
low-LET radiation are due to qualitative
difference has not yet been established. It
seems likely that the dependency of biological
response on radiation quality has at least to be
exploited with quantitative difference arising
from pattern of energy deposition. In this point
of view, we are attempting to exclude the
biological effects of high energy of helium alpha
particle radiation by using plant cells with
emphasis on the quantitative analysis of
cellular growth and chromosome aberrations
induced within cells.
In previous study3), we have examined the
dose effects ranging from 50 to 500 Gy on
germination of dry seeds of three different
species of plants, Triticum, Brassica, and
Allium, and also on mitosis in root tip cells of
Allium. The present study was aimed to
explore the effects of relatively low doses of
radiation (ranging from 1 to 20 Gy) on Allium
seeds. The technique, however, to allow more
detailed observations of chromosome
aberrations and its structural changes has not
yet perfect in the case of onion root tip cells'150'.
An exploration of technical adventure is also
another important purpose of this study.
2 Materials and Methods
In this experiment, the dry seeds of onion,
Allium cepa L. cv. Senshu-chuko-kitamanegi,
were used for studies upon biological effects of
JAERI AVF cyclotron produced helium alpha
particle beams.
1) Preparation of Irradiation Samples.
Experimental seeds were attached to 3 en? of
fixed area in the central part of irradiation
vessels, in which about 100 grains of usually
prepared forone dose experiments. Each group
of dishes was consisting of whole experiment
- 3 1 -
JAERI-Review 95-019
with graded doses of radiation.
2) Radiation. Helium ion beams (12.5
MoV/rrt were produced under operation of
JAERI AW cyclotron, and the dry seeds of
Allium cepa wex-e irradiated by using the
JAERI devised so-called * plant seeds
irradiation apparatus " . The physical
description of He2+ ion beams will be referred
elsewhere in other report from Biotech. Lab.,
JAERI.
3) Seed germination. The irradiated as well
as un-irradiatod samples of dry seeds were
placed on a water dipped filter paper in a glass
petri dishes (90 mm in a diameter) , and kept
in 25 °C. During the incubation period, the
number of seeds germinated were scored every
24 hr interval, and the length of roots sprouted
were also measured to score the number of
roots grown longer than 5 mm, which allowed to
be used for cytological studies.
4) Cytological preparation. Root tips grown
longer than 5 mm can be used for cytological
studies. These root tips wore transferred into
cold water including 0.05 % colchicine, and
incubated in ice-cold atmosphere for 24 hrs
before fixation with acetic-alcohol (1 '. 3
mixtures). After fixation, root tips were placed
in 0.2 N II Cl for about 15 min. at 30°C and
treated with 2 %cellulase at pH 4.5 for about 2
hrs. The enzyme digested root tips were
squashed with aceticorcein stainingon a slide.
3 Results
Table 1 shows the germination of irradiated
and un-irradiated seeds during 5 clays
incubation period at 25 °C. There are no
significant differences among those of 7
different dose groups on the germination rate.
Fig. 1 shows an increase of % germination
which permitted the growth of root tips into 5
mm length or longer during the incubation at
25 0. germination of seeds during 24 hrs was
about 6.G % in the un-irradiated controls and
2.5 ~- 6 % in those of irradiated groups. The
rates after 48 hrs incubation was about. 25.5 %
in the controls and 18.5 — 40 % in the
irradiated samples. It looks a sort, of inhibition
of germination in the irradiated seeds, but the
result in Fig. 1 clearly indicates that there is no
effective inhibition in the irradiated groups on
the growth of sprouted seeds in terms of
elongation of root tips. The result was
completely in agreement with the results
observed with 8 Gyof helium ion beams, small
dot like ring and possible translocations. Even
with 1.0 Gy of irradiation the irradiated cells
was apparently found to contain pieces of
chromosome aberrations within nucleus. The
more detailed study on chromosome analysis is
now undergoing in Okayama University, but
has not yet completed. The results, however, at
least suggested that chromosome aberrations
induced by such low dose may have no relation
with growth integrity of root tip cells in Allium
cepa.
4. Discussion
The chromosome preparation for the study of
aberration frequencies in the irradiated cells
may require sort, of well-spread metaphase
cells, in which each component of chromosomes
should be separated from another, in both of
plant and animal cells. In this respect, plant
cells appear still difficult in general to obtain
a well-spread metaphase plate unlike those of
animal cells in mitosis. An effort, for such
technical development is now undergoing, since
accurate measurement of chromosome
aberrations may be required for understanding
of primary molecular damages at critical target
- 3 2 -
JAERI-Review 95-019
with different quality of radiation, particularly
in the study of RBE vs. LET.
In another respect, an apparent diflbronro
with radiation sensitivity can be recognized to
exist between plant and animal cells in various
kinds of biological indexes. As shown in the
previous study, growth of Gallium cepa root
tip cells was not inhibited with doses under
20 Gy, by which no significant cell killing was
not suspected, while animal cells was
completely inactivated without exception. This
difference may have not intimately with actual
induction of chromosome aberrations observed.
The result of the present study suggests a
validity of this hypothesis in part, because it is
probably possible that induction of
chromosome aberrations may not be much
different between animal and plantcells. A
big difference in the sensitivity between animal
and plant cells in terms of cell growth and
killing as well seems to be an other problem.
5.References
l)D.T.Goodhead,Int.J.Radiat Bnl. 65(1994),
7.
2) C.R.Geared, Radiat.Res.104 (1985), S-112.
3) H.Ohara, N.Inomata, H.Watanabe,
A.Tanaka.Y.Kobayashi, M.Kikuchi, JAERI
Ann. Rep. vol.3 (1994),38.
4) S.M.Stack and D.E.Comings, Chromosoma
(Berl.) 70, (1979), 161.
5) I.Schubert and R.Rieger, Eukaryotic
Chromosomes, ed.by R.C.Sobti & G.Obe,
Springer Verlag & Narosa Publishing House
Table 1. Germination of Allium ccpa seeds with
low dose of JAERI He ion beam irradiation .
6) M.Murata, Stain Technology vol.58
(1983), 101.
un-irradiated controls
1
3
5
8
10
20
'
Gy
Gy
Gy
Gy
Gy
Gy
irradiated
irradiated
irradiated
irradiated
irradiated
irradiated
seeds
seeds
seeds
seeds
seeds
seeds
* germinated/plated
187/198*
184/200
186/200
176/198
186/200
89/100
90/98
0.944%
0.
0.
0.
0.
0.
0.
920
.930
889
.945
.89
918
Cummuratlve % ol seeds grown longer than 5 mm
100
cse
eds
grc
I
I>m
Cum
m80
60
40
20
C
-20
Cont(%)• iGy/He .• 3Gy/Hea 5GY/He .D 8Gy/Hea lOGy/He- 20Gy/He
1 2 3 4 5 6days alter seedlings In waler
Fig. 1. Increase in % of seeds germinated and
grown into 5 mm length of root tips or longer.
Fig.2. Post irradiation mitotic metaphase of
cells irradiated by JAERI He ion beams (8 Gy),
showing at least 2 kinds of aberrations.
- 33 -
JAERI-Rcvicw 95-019
2 . 4 Studies on induced mutations by ion beam in plants
H.Nakai, ELWatanabe*, S.Kitayama", ATanaka*, Y.KobayashT,
T.Takahashi**, T.Asai and T.Imada
ShizuokaUniv., *JAERL **RKEN
Introduction
we have tried to study on the use of ion
beams for plant mutation breeding of rice,
especially aiming at development of varietes
resistant to bacterial leaf blight(BLB), caused
by Xanthomonas pv. oryzae. Fortunately, we
could select some BLB resistant mutants in
the populations derived from seeds exposed
to ion beams.
In addition to BLB, we started experiments
on selection of induced resistant mutants of
rice to blast, caused by pvricularia oryzea
Cav.which is one of the most important
disease of rice all over the world. There are
many problems unsolved especially on the
screening method for the blast resistant
mutants.
The result of a preliminary experiment on
the above subject is reported in this paper.
Materials and Methods
Dry seeds of rice, Orvza sativa L.,c.v.
koshihikari, were irradiated by ion beam
(He24) from the AVF cyclotron in JAERI
operating at 50 MeV. On the other hand, for
comparison, the seeds were exposed to
thermal neutrons with a flux of 2.5 X
lO'Nth/cm/sec for 0-6h in the heavy water
facility of Kyoto University Reactor operated
at 5000KW, and exposed to gamma-rays of
0-600Gy from a ^Co source. After
irradiation with three mutagens, the seeds
were brought back to Shizuoka University to
grow in the isolated experimental field. In
this Mi generation, seedling height, root
length, pollen and seed fertility were
measured for analyzing the radiosensitivity of
the mutagens used(I). M2 seedlings
originating from the treatment of each
mutagen, which decreased the seed fertility
of Mi plants to be about 50% of non-
irradiated control, were screened for blast
resistance. The M2 seedlings were artificially
inoculated by putting the blast infected
leaves of rice on the seedlings. The
inoculated seedlings were kept in extremely
high moisture conditions to stimulate
development of the disease.
The seedlings which showed resistant to
blast were selected to be transplanted in the
isolated field. At adult stage, the plants were
again inoculated by the same method to be
checked for resistance to blast.
In the M2 tests, in addition to blast
resistance, chlorophyll mutations were
examined.
Results and Discussion
Fig. I shows frequency of chlorophyll
mutants including white, pale green, yellow
green, yellow ,stripe seedling etc. in each
mutagen. In each mutagen, the frequency was
increased with increasing dose. It was noted
that the frequency in high LET radiation, ion
- 3 4 -
JAERI-Review 95-019
2.5
1.5
1
0.5
n
1I * ///
/
(aK1 • *^^T'1 • ^ ^
N:HG:A
_ ^ . * "
0 100 200 300
Dose (Gy)
Figl. Frequency of chlorophyll mutants
400 500
(a) I: ion beam(He2+)G:gamma-rayN: thermal neutron
0
0 100 200 300
Dose (Gy)
Fig2. Frequency of blast resistant mutants of rice
400 500
(a) I: ion beam(He2+)G:gamma-rayN: thermal neutron
- 3 5 -
JAERI-Rcvicw 95-019
Table!. Frequency of blast resistant mutants of rice in each mutagen
No. of No. ofMutagen^ Dose M, seed fertility seeds sown INO> U l Frequency
mutant(M2)
(a) I: ion beam(He ), G:gamma-ray, N: thermal neutron
1
G
N
80100120160300400500
14.7319.6429.64
60.554.659.031.778.1
57.320.457.366.1
20.2
12000
45004200
1500
21000
6000
3000
13500
10500
1500
12
41
5
27
9
9
3
100
0.1000.089
0.024
0.3300.130
0.150
0.300
0.022
0.0950.000
beams or thermal neutron was higher than in
low LET gamma-rays. Frequency of mutants
resistant to blast is shown in Fig.2.
As seen in the figure, dose-responses for
frequency of blast resistant mutants in the
mutagens were similar to those for that of
chlorophyll mutants. It needs to note that in
this case, the highest mutation frequency was
found in the ion beam treatment. We
previously reported that ion beams could be
very efficient mutagen to induce mutants
resistant to BLB in rice(2).The result of this
preliminary experiments suggests that ion
beams are useful mutagen to induce mutants
resistant to blast in rice.
References
l)H.Nakai et al., TIARA Annual Report
Vol.2(l 992)54.
2)H.Nakai et al., Plant Breed Sci. 44
(Suplraent) (1994)290.
- 36 -
JAERl-Review 95-019
2 . 5 Comparative analysis of interspecific hybrids between Nicotiana
gossei Domin and N. tabacum L., obtained by the cross with ' He2 *-
irradiated pollen
Takao YAMASHITA, Masayoshi INOUE, Hiroshi WATANABE2,
Atsushi TANAKA3 and Shigcmitsu TANO3
Department of Agriculture, Kyoto Prcfcctural University,
Department of Radiation Research for Environment and Resources, JAERI2,
Advanced Sci. Res. Center at Takasaki, JAERI3
Introduction
In wild species, there are valuable genes
controlling resistance to diseases and insects. The
introduction of such genes from wild species to
cultivar is extremely useful in plant breeding.
However, owing to various barriers to sexual
reproduction, e.g. cross incompatibility and hybrid
inviability, obtaining a hybrid between distantly
related species is very difficult or impossible in
some cases4'6'. In Ar. gossci (wild species) >
A', tubncum (cultivar), it is easy to get hybrid seeds
with conventional cross, but hybrid plants can not
survive. On the other hand, in A', tabacum >
Ar. gossci, few seeds with viability can be
obtained.
Because A', gossci has been reported to be
resistant to more diseases and insects than other
Nicotiana species, several attempts to hybridize it
with A', tabacum have been made. A few hybrids
were produced by the cross using susquidiploid
and tctraploid1)i2)i7), but they did not show
resistance similar to that of A', gossci.
In the previous paper5), we showed that
"'He^-irradiation to pollen was effective for
overcoming hybrid inviability in F, plants between
Ar. gossci and Ar. tabacum. In the present study, we
carried out random amplified polymorphic DNA
(RAPD) analysis , characteristic analysis on
trichome on leaf surface and preliminary test for
resistance to tobacco mosaic virus (TMV) and
green peach aphid, My/.us pcrsicac Sulzer, in
interspecific hybrids and their parents.
Materials and Methods
Interspecific hybrids between Ar. gossci and
Ar. tabacum, produced by the cross with 4He2+-
irradiated pollenS), were used. Briefly, mature
pollen was collected from N. tabacum cv Bright
Yellow 4, immediately after anthesis, irradiated
with 800Gy of 4He2t beam from 3MV tandem
accelerator (6McV), and pollinated to the flowers
of A', gossci, already emasculated before anthesis.
Consequently, two viable hybrid plants were
obtained at the rate of 1.1 x 10"3. They developed
up to flowering time, but had no seeds. So, they
were propagated by cutting. Additionally, another
line of interspecific hybrid between N. gossci and
A', tabacum, obtained through the same procedures
except lOOGy gamma-irradiation to pollen, was
also analyzed. In the case of gamma irradiation to
pollen9), the rate of hybrid was 3.7 >• 10s.
All plants used here, were cultured in the
greenhouse with natural day light, at 25-30°C
(Table 1).
Table 1 Interspecific hybrids between N.gosseiand N. tabacum
line Cross to N. gossei
ion-1 BOOGy 4He2+-irradiated pollen
ion-2 800Gv4He2 + -irradiated pollen
gamma-1 100Gy gamma-irradiated pollen
- 37 -
JAERI-Review 95-019
RAPD analysis
Whole DNA was extracted from very young
gossci and N. labacum had a band around 702 bp
and between 702 and 1264 bp, respectively, and
iCJV'CS, JCCGIuing tO tnC IliCtnOu Ui DclilipOrta CL CaCn llj't'JnCi ilau tWO JuiiuS i.TO
a/.(1983)3), and RAPD markers were developed
using 15 random lOmer primers (Kit A, Operon
Technologies). The reaction of 45 cycles was
carried out, following the procedure of Williams ct
al. (1990)8), at the annealing temperature of 43°C.
After reaction, the products were analyzed by
agarosc gel electrophoresis.
Trichome analysis
Leaves with length of 12 to 15cm, were
collected at the flowering time, and epidermis was
used for determining density and type of
trichomes on leaf surface by light microscope and
scanning electron microscope.
Resistance test
After carborundum application on leaf
surface of 2-3 young leaves in each tested plant ,
TMV suspended in buffer solution was inoculated.
Plants were kept in a greenhouse for 3 to 4 weeks,
and, then, disease symptoms, e.g. mosaic, curled
leaf and mottled flower, were recorded to
differentiate the degrees of resistance to TMV.
TMV test was repeated 3 times, using 3 plants in
each line.
For the incubator tests of aphid resistance,
young leaves were collected, inserted into the
bottle with water, and kept in the incubator
controlled at 25CC. Infestations were produced by
the transfer of 5 to 10 apterous aphids on each leaf
surface. During the period of 10 days, number of
surviving aphids was recorded daily.
Results and DiscussionThe band pattern in RAPD analysis
revealed the hybridity of F, plants, clearly. As
shown in Fig. 1, the most remarkable combination
of bands in hybrids was observed in OPA-07 ; N.
Furthermore, in OPA-01, both of ion-1 and ion-2
had one additional band, which was not detected in
gamma-1. From these results, it is suggested that4Hc2+-irradiation to pollen is available for
introducing alien gene(s) to cultivar through
sexual reproduction in wide cross, and also that
hybrids obtained may be different in genetic
composition, resulting from chromosome breaks
and/or very small mutation.
OPA- 0 1 OPA-07
(bp)
2323-1929-
1371-1264-
702 -
Fig. 1 RAPD profiles of hybrids and parents.
Fig. 2 Head cell(s) of trichome in N.gossei
( lef t ) , hybrid (center) and N.tabacum
(right).
- 38 -
JAERI-Rcview 95-019
Table 2 Trichome density and type in N. gossei,hybrids and N. tabacum.
Line
N. gossei
N. tabacum
gamma- 1
i o n - 1
i o n - 2
No. cf
trichomes/mm2
62.6
104.7
76.5
26.3
64.1
glandular87.644.462.'968.968.3
Trichcmehydathode
12.434.626.520.126.5
type {%)simple
0.0
21.010.310.7
4.8
branched
0.0
0.1
0.3
0.3
0.4
The characteristics of top part of trichome
was exhibited in Fig. 2. In A', tabacum, two or
three head cells were observed and they had
chloroplasts. However, in N. gossci, single head
cell without chloroplast was found. In hybrid, the
top part of trichome was intermediate between
their parents, indicating that this morphological
difference could be used for identification of
hybridity. Table 2 shows trichome density and
percentage of different trichome-types. Trichome
density in hybrids was significantly lower than
that in A', tabacum. Particularly, the density in ion-
1 was about a half of A', gossci. Percentage of
glandular trichomes and hydathodes in hybrids
was intermediate between the parents. Simple and
branched trichomes were not observed in
A', gossci.
From the preliminary test for TMV
resistance, it was recognized that gamma-1 was
resistant at the similar level to that of A', gossci.
Both of ion-1 and ion-2 were much more resistant
than A', tabacum, but the degree of resistance was a
little lower, corr.pared to that in A', gossci.
Furthermore, aphid resistance appeared to be
introduced to all hybrids ; mean survival period
after infestation of aphid on leaf surface, was 1,
2.5, 2.4 and 3.7 days in N. gossci, ion-1, ion-2 and
gamma-1, respectively. In the leaf of Ar. tabacum,
aphid continued to survive over 10 days and grew
up.
In the present study, molecular and
morphological differences between interspecific
hybrids and their parents were made clear. It was
also suggested that each hybrid was resistant to
TMV and aphid although the degree of resistance
varied among hybrids.
References
1) Apparao, K., K. T. Ramavanna and 13. (j. Joshi, Tob.
Sci. 24:46-48(1980)
2) Hurk, L. (i. and C. E. Dean, Eupliytica 24: 59-63
(1975)
3) Deilaporta, S. L , J. Wood and J. 15. Hicks, Plant
Mol. Hinl. Rep. 1 (4): 19-21 (1983)
4) Goodspeed, T. H., Chronica Botanica, Waltham
Mass. (1954)
5) Inouc, M, 11. Watanabe, A. Tanaka and
A. Nakamura, TIARA Annu. Rep. 3 : 44-45 (1993)
6) Takcnaka, Y., Hot. Mag. Tokyo 75:237-241 (1962)
7) Thurston, R., J. Economic Entomology 54: 946-
949(1961)
8) Williams, J. G. K., A. R. Kubclik, K. J. Livac,
J. A. Ralalski and S. V. Tingcy, Nucl. Acids Res.
18:6531-6535(1990)
9) Yakushiji, H., M. Inoiic, and A. Nakamura,
Jpn. J. Breed. 40 (2): 444-445 (1992)
- 3 9 -
JAERI-Review 95-019
2 . 6 Photomorphogenic Mutants of Arabidopsis.(I) Isolation of Mutants Using EMS-Treated andIon Beam-Treated Seeds
Hiroaki ICHIKAWA, Atsushi TANAKA* and ShigemitsuTANO*Department of Molecular Biology, National Institute ofAgrobiological Resources and *Advanced ScienceResearch Center at Taskasaki, JAERI
IntroductionLight is essential to plants not only as a
source of energy via photosynthesis, but as an
environmental factor that alters plant growth
and development. The light-dependent process
of plant development, referred to as
photomorphogenesis, is composed of three
phases: (a) perception of the light signal, (b)
signal transduction, and (c) physiological and
developmental response (1). Several classes
of photorcccptors contribute to the perception
of the light signal. They include the
phytochromes (rcd/far-rcd light receptors),
blue light pholorcccptors, UV-A
photorcccptors and UV-B photorcccptors. The
isolation and characterization of a number of
pholomorphogcnic mutants from Arabidopsis
is proving especially useful for unraveling the
function of photoreccptors and light-dependent
signal transduction cascades, and for the
isolation of genes coding photorcceptors and
genes for signal transduction components (2).
It has rcccnliy been believed that the
irradiation of heavy-ion particles would be very
efficient for causing the deletion and/or
rearrangement of DNA molecules in living
cells. In this study, we have been isolating
and characterizing Arabidopsis mutants
deficient in suppression of light-signal
transduction using M2 seeds treated withethyl methane sulfonatc (EMS) and heavy-ionparticles.
Isolation of EMS-treated mutantswith short hypocotyls
EMS-mutagcni/.cdM2 seeds of Arabidopsis
wild type (ccotypc RLD; 35,000 seeds in total
and derived from 13,000 Ml seeds) were
surface-sterilized, sown on MS medium, and
grown for 7 to8 days at 22°C underconlinuous
yellow light (40 |.unol/m2/scc) which contained
no blue light and low amount of red light.
We initially isolated 34 seedlings, which
showed growth inhibition of hypocotyls under
yellow light, as primary candidates among M2
plants tested. Those plants were transferred to
soil for M3 seed setting. Two independent
lines (YL5-A and YL7-J) of the 34 lines were
finally selected as photomorphogenic mutants
by testing growth of M3 seedlings under
yellow light, red light and in darkness.
Hypocotyl growth of the two mutant lines was
strongly inhibited under yellow and red lights.
They were not distinguished from that of wild
type under white light and in the dark (Fig.
1). The results indicated thai the mutant lines
were clearly distinguishable from del and cop
mutants which showed short hypocotyl
- 4 0 -
JAERI-Rcwcu 95-019
phenotype under yellow light and "dc-
ctiolated" phenotypc in the dark. Western blot
analysis showed that no qualitative and
quantitative differences in phytochrome A
(PHYA) and PHYB proteins were observed
between the mutant lines and wild type
seedlings (Nagatani and Ichikawa, unpublished
results). The genetic complementation test of
those mutants demonstrated that the two lines,
YL5-A and YL7-J, were allelic. When crossed
with the wild type plants, the mutant phenotype
turned out to be recessive. Consequently, it
was suggested that the two lines would have
a mutation in light-signal transduction from
the phylochromc molecules. The genetic
mapping of the mutant locus is in progress.
16
Dark Y-50 W-100
Light conditionFigure 1. Photomorphogcnic mutants (YL5-A
and YL7-J) show short-hypocotyl phenotype
when grown under yellow light. Y-50: 50
Hmol/m2/sec of yellow light; W-100: 100
[.imol/m2/sec of white light. Values are the
mean ± SEM for 30 seedlings.
Isolation of short-hypocotyl mutantswith heavy-ion beam irradiation
Each 10,000 seeds of Arabidopsis wild-
typc (ccotypc Columbia) were irradiated with
100 Gy and 200 Gy of heavy-ion particles
(12C5* 220 MeV) using the AVF cyclotron in
TIARA. The ion-beam treated Ml seeds were
sown and grown in a greenhouse. M2 seeds
were harvested and pooled separately at every
100 Ml plants. The screening of short-
hypocotyl mutants was performed with M2
seeds which were treated with 100 Gy of ion
beam (ca. 120,000 seeds). The conditions for
the mutant screening using yellow light were
almost identical to those as described above.
Two hundreds and ninety M2 seedlings were
selected as primary candidates for the mutation.
The second screening of the mutation using
M3 progenies of the primary candidates is in
progress.
Heavy-ion beam irradiation has a potential
which cause DNA deletion and as a result
mutation of gcnc(s) in living organisms. The
isolation of ion beam-induced mutants would
be extremely useful for the isolation of gcnc(s)
of interest using genomic subtraction
procedure (3) and for the elucidation of the
function of the mutated genes.
References(1) P. H. Quail, Annu. Rev. Genet. 25, 389
(1991).(2) J. Chory, Trends Genet. 9, 167 (1993).(3) N. Lisitsyn, N. Lisitsyn and M. Wiglcr,
Science 259, 946(1993).
- 41 -
JAHRI-Rcvicw
2 . 7 Dynamic Observation of Transportation of Water in Plants byUsing Positron-Emitting Isotope - Effect of Temperature
Takashi Fujimura", Katsuhiko Adachi0, Hideki Omichi0, Hiromitsu Matsuoka2),Noriko Shigeta2), Toshiaki Sekine2), Hiroshi Uchida3), Takaji Yamashita3), KenjiOmasa1", Makoto TakoT\ and Ikirumichi KobasliiM
l)Department of Material Development, JAERI, 2)Department of Radioisotopes,JAERI, 3)Hamamatsu Photonics Co., 4)National Institute for EnvironmentalStudies, 5)Gunma University
IntroductionWe have been working with the
utilization of positron-emitting elements forthe observation of materials in plants whichare kept under the normal living condition.By the end of last year, it was made clearthat the movement of water containing aminute amount of ISF positron-emittingisotope introduced into a plant wasdynamically followed by a specialobservation apparatus called "POSITRONCAMERA".
This year we studied the effect oftemperature on the movement of water inplants with this technique. The reason ofthe study is related with the fact that thetemperature is one of the key factors tocontrol the growth of plants. For example,many kinds of plants should be kept warmin winter season in order to keep themalive. It is quite sure that the activity ofplants are decreased at lower temperature.However, until now, no detailedmechanism has been reported withreasonable experimental data. The newtechnique with the position camera has apotential to realize the difference inmovement of water in plants kept atdifferent temperatures.
In the present study, the root ofkidney bean was put in a thermallycontrolled water bath while the other partwas kept at a constant temperature.
ExperimentalAn aqueous solution of 1SF was
produced by the reaction of 16O (a, pn) 1SF
through the bombardment of water with a
panicles of 50 MeV, 1.1 |iA from theTIARA AVF cyclotron. It took 20 minbombardment in order to produce 50 MBqof 1SF from 6 ml of pure water.
The kidney bean (Phaseolusvulgaris L.) was supplied to the experimentafter it was cultivated by the hydroponics
method in a thermally controlled room. Theroom temperature was kept at 25 °C duringdaytime while it was at 15 °C at night. Theheight of the plant reached ca. 30 cm fromthe root to the top through the 4 weeks'cultivation.
The positron camera is composed ofa scintillator array coupled to a position-sensitive photomultiplier tube (HamamatsuR3941-2), a computing unit and a display.The scintillator array is the assembly ofBi4Ge3012 scintillators of the size 2 mm x 2mm x 20 mm in a shape of 50 mm x 48 mmsquare. A pair of the assembly is located ina face to face position with a distance of 12cm. The plant is installed between the two
scintillator plates. The signal of a pair of y-ray produced by the positron-electronrecombination is detected by the detector.The simultaneity is assured within 20 ns.
The root of the kidney bean plantwas put in a water solution containing ca.1.5 MBq/ml 18F which was kept at either 25°C or 5 °C. The other part of the plant wasilluminated by a fluorescent lamp in order tohelp the movement of water in the plant.The brightness and the temperature at the
leaf were 300 |imol-photon/m2.s and 27 °C,respectively. The measurement wascontinued for 120 min. Then, the data wereanalyzed by the computer.
Results and DiscussionBecause of the limited size of the
plate detector, the distribution of 18F wasfollowed only in one leaf which was put inthe central position of the detectors. The
signal of y-ray was accumulated for 2 min.Fig. 1 shows the distribution pattern of 18Ftaken up in 2 h to the leaf at the top of theplant from the root kept at (a) 25 °C and (b)5 °C. The intense population of 18F is seenat the joint of the leaf and the stalk at 25 <Cwhile no clear difference in concentration isobserved in the case of 5 °C.
- 4 2 -
JABRl-Review 95-019
(a) (b)Fig. 1 Distribution pattern of F taken up in 2 h to the leaf located at the top of the plant fromthe root kept at (a) 25 °C and (b) 5 °C.
The gradual decrease follows theveins of the leaf in Fig. 1 (a). This isbecause the movement of F is fullyattributed to that of water. However, it doesnot mean that all the 18F elements are carriedto the leaf. It is quite possible that a part of18F still remains in the water layer withoutbeing sucked by the root. In a separateexperiment, it was observed that thedecrease of water in the water bath was 21% while that of 18F was only 2 % in 2 h.One of the reasons for this discrepancy ofthe movement between water and 18F maybe related with the activity of the cell of theroot. The separation of such a foreignelement as F may be the importantfunction of living plants. In spite of thisdifference in movement between water andother elements dissolved in water,however, the detection of the latter elementin plant gives an important informationwhich reflects the movement of water.
Fig. 2 shows the comparison oftime dependency of the activity of 18F in theleaf between 25 °C and 5 °C. The activityincreases exponentially at 25 °C while it isalmost constant at a low level at 5 °C. Theformer is ca. 30 times the latter in 2 h. Thedifferent activity of 18F between the twocases is only due to the difference intemperature of the root dipped in the waterbath. The result of Fig. 2, therefore,quantitatively indicates the effect oftemperature of water suction on the activityof the root cell.
A further study will be continued toclarify the distribution of nutrients such assaccharoid in leaves.
100
20 40 60 80
time (min)100 120
Fig. 2 Comparison of time dependency ofthe activity of 18F in the leaf between 25 °Cand 5 °C.
- 4 3 -
JAKRI-keview 95-019
2 • 8 RBE / LET Effects of Heavy Ions on Inactivation inDry Cells of Deinococcus radiodurans
.*Y Kobayashi , T. Shimizu , A. TanakaG. Taucher-Scholz** and H. Watanabe*Biotechnology Lab., Takasaki, JAERI;
.*M. Kikuchi
Biophysik, GSI-Darmstadt
ABSTRACTInactivation induced by heavy ions was
studied in dry cells of radioresistant bacteriumDeinococcus radiodurans. All survival curves werecharacterized by a large shoulder of the curves. No finalslopes of the exponential part of survival curves forheavy ion irradiation were steeper than that for 2.0MeV electron irradiation. The plots of RBE versusLET showed no obvious peaks, suggesting that thisbacterium can repair not only DNA double strandbreaks (DSBs) but also clustered damage in DNAwhich may be induced by heavy ions.
INTRODUCTIONThe induction and processing of DSBs in
DNA have been considered to be the predominantdeterminants of radiotoxicity because the patterns ofDSB/LET response are comparable to the shape ofLET responses for cell lethality1). However, currentinformations obtained from precise analysis of DSBsin cells demonstrate the absence of LET dependence ofDSBs. Clustered damage in DNA are considered as the
dominant damage of DNA for cell lethality2).The extraordinary radiation resistance of
Deinococcus radiodurans has been ascribed to theability to repair all DNA lesions including doublestrand breaks (DSBs) induced with doses up to 5kGy3-4). It was reported that this bacterium was alsoresistant to heavy ion irradiation and the survival curvehad a large shoulder5'6), suggesting that thisbacterium can also repair DSBs induced by heavy ions.Therfore we expected no LET dependence of RBE forinactivation of D. radiodurans. However, RBE peakwill be observed in LET response if this bacterium cannot repair the putative dominant damage for celllethality: clustered damage in DNA.
In this study, we examined the survivalresponses in detail in dry cells of D. radiodurans afterheavy ion irradiation with particles of variousenergies.
MATERIALS AND METHODSD. radiodurans Rj strain was cultivated in
TGY liquid medium (0.5% Tryptone, 0.3% yeast
extract, 0.1% glucose) with shaking at 30'C for 24hrs. Stationary phase cells were lyophilized onmembrane filters (pore size 22 |i.m, MilliporeCorporation) as a monolayer and irradiated in theatmosphere.
Exposure to He, C, and Ne ions from AVFcyclotron was carried out at TIARA in JAERI-Takasaki; exposure to Ar, Ni, Xe and Au ions wascarried out at the UNILAC in GSI-Darmstadt. Withrespect to 12.1 MeV/u 1 2C, 11.9 and 6.5 MeV/u20Ne, 2.8 MeV/u 40Ar, 5.9 MeV/u 58Ni, 4.4 MeV/u12^Xe and 5.4 MeV/u ^ 7 A u ions irradiation, theparticle energies were degraded with absorbers to obtainvarious LET values on the target. Particle fluenceswere determined using track detector (CR-39 film andglass). LETs were calculated with ELOSS codedeveloped in JAERI. The dry cells were also irradiatedwith 2.0 MeV electron beams from a Cockcroft-Walton accelerator at JAERI-Takasaki.
Following the irradiation, the dry cells weretransferred onto TGY agar plate and surviving colonieswere counted after 3 days incubation at 30°C.
RESULTS AND DISCUSSIONFig.l shows the dose response curves of the
dry cells of D. radiodurans R | irradiated with heavy
ions. All survival curves are characterized by a largeshoulder of the curves. In case of heavy ions no finalslopes of the exponential part of the curves weresteeper than that of 2.0 MeV electrons.
The inactivation cross sections determinedfrom the final slope of the survival curves are plottedin Fig.2 as a function of LET. The plot does not showthe saturation of cross sections at LET values up to
104 keV/u.m, however the cross sections at 104
keV/u,m comes near the target size (about 1 |im2) ofcells. Characteristic hooks seem to begin in the datapoint for Ne and Ar ions.
Fig.3 is a plot of the RBE values determinedfrom the ratios of inactivalion constants (Do) obtained
for heavy ions and 2 MeV electrons as a function ofLET. Reflecting the final slopes of the exponentialpart of the dose-effect curves shown in Fig.l, no
- 4 4 -
JAERl-Review <-)5-(H9
obvious RBE peaks are found in LET response.To confirm the changes in shoulder of the
curves, the dose required to reduce survival to 10% wasplotted as a function of LET as shown in Fig.4. Thedose keeps similar value at LET values up to 2000keV/|im and then increases steeply to high doses atvery high LET. It is also clear from this plot that theRBE at 10% survival shows no obvious peaks in LETresponse.
It has been widely accepted that the criticalradiation-induced DNA lesion finally causing cellinactivation is the non-repaired DNA double strandbreaks. Therefore, the RBE/LET pattern shown inFig.3 seems to reflect the ability of this bacterium torepair DSBs induced at various LET. We have obtainedan evidence of its ability to repair DSBs induced athigh LET. Total post-irradiation incubation limerequired to complete the repair of radiation inducedDSBs was analyzed by detection of the reappearance ofthe ladder pattern of genomic DNA digested with arestriction enzyme using pulsed field gelelectrophoresis. From the results no differences wereobserved between y-rays and high LET heavy ions onthe repair time at the same dose6). Furthermore, fromthese facts there would be no difference in radiationinduced DSBs at LET values of 0.2-2000 kcV/^m atleast from the view point of repair ability of D.radiodwans. If the clustered damage is the critical DNAlesion for cell lethality, LET independence of RBE for
inactivation of D. radiodurans suggests that thisbacterium can repair not only DSBs but also clustereddamage in DNA which may be induced by heavy ions.
REFERENCES1. Lett, J.T., Damage to cellular DNA from paniculateradiations, the efficacy of its processing and theradiosensitivity of mammmalian cells. Radial.Environ. Biophys. 3 1, 257-277 (1992).2. Goodhead, D.T., Initial events in the cellular effectsof ionizing radiations: clustered damage in DNA. Int.J. Radial. Biol. 6 5,7-17(1994).3. Kitayama, S. and Matsuyama, A., Possibility ofthe repair of double-strand scissions in Micrococcusradiodurans DNA caused by gamma-rays. Biochem.Biophis. Res. Commun. 33,418-422(1968).4. Kitayama, S. and Matsuyama, A., Double-strandScissions in DNA of Gamma-irradiated Micrococcusradiodurans and their Repair during PostirradiationIncubation. Agr. Biol. Chem. 3 5, 644-652 (1971).5. Dcwey, D.L., The survival of Micrococcusradiodurans irradiated at high LET and the effect ofacridinc orange. Int. J. Radial. Biol. 16, 583-592(1969).6. Kikuchi, M., Kobayashi, Y., Tanaka, A., Shimizu,T. and Watanabe, H., DNA double-strand breaks andthe repair in radiorcsistant bacterium, Deinococcusradiodurans, irradiated by ion beams. JAERI TIARAAnnual Report 2, 34-37 (1992).
co
&
>
3
100<
10
1
0.1
< 1 l \
1
t
i
-
1 1 ' 1
<\
; i • • i i I I
i< < 1 ) >
< < \ } y
TO
\
• • i 1 i
i 4
4 4
z
:
0 10 20Dose (kGy)
30 40
Electron 2.0MV
— • — He 2SMeV/u
—*— He 11.7MeV/u
—•—He 4.1 MeV/u
— • — He 0.96 MeV/u
—G—C 17.3 MeV/u
—a—C 12.1 MeV/u
— a - Ne 15.9 MeV/u
— a — Ne 11.9 MeV/u
—O— Ne 6.5MeV/u
—f*— Ar S.S MeV/u
— s — Ar 2.8 MeV/u
—G—Ni 13.8 MeV/u
—A— Ni 5.9 MeV/u
—X— Xe 9.1 MeV/u
— ) — Xe 4.4 MeV/u
—©— Au 8.9 MeV/u
- A u 5.4 MeV/u
Fig.l Survival Curves of dry cells of D. radiodurans irradiated withelectrons and heavy ions.
- 45 -
JAERI-Review
8 10"8oore
-3
Urec
io
IO-4
:••::;:: itr ;::::r::::^':::::u::l:':':;:::::::::::t:f:::;:"::'::!:;^:t:':::!::::::::::i".t:":::
-
ill
X electron
0 He
O c
• Ne
• Ar
D Nl
• Xe
• • • • • - : • - : • : : : ; : : % • - { - • i - i -
ff-Ti11fi-*111ta!!|!^i£!!{[:!!!s!iyi:|:ii(ii:SiEfc!:iiT-r-i-ftT.-:! T-r-:-:-:4:i: r :•:•
T"T"T:T"I " " "T-Tf-I T"rrV
< >» <..^.t.LB-..»>......(...t-.)-1-M (•
?l!!"6t"i""m? niT:;:;; r
rr:: f—/-T-vrrrrr :—:-:-:-vrrr :•
j|ii;!iii|;:|i|;|:i!?|!i!i!:|::j::|;i:;iSJ;:;;!h:~:i f—:-:-:-:--rr ••—.••:-.r:rr? :•
~:i -•••••••"••~r " • • • " • • • • " H ••
0.1 1 io io2
LET (keV/jim)
Fig.2 Inactivation cross sections of D. radiodurans as a function of LET.
1 -
03
0.1 -
: : : :::: l • • : : : : . : l : : : : ::::l
•••:^:n;:[;;;-::::::i::-:;:r«-0-r--ti;::::-:-:
_...*.v-..^..ff....
X electron
0 He
o c• Ne
• Ar
D Nl
A Xe
O Au
; • ; ; i i i ! j : : : : : : . i | : : : : : : : |
: i : •: 1 : • : • : : : : l :
-••Hiirili: : •.:::
• t : - ; K - M :
^.
• ! : : : : : : : :
; i illllio :
• • ' . • : • ; ; • : ' • . - • • • : • • : • : < y . t
0.1 1 10' 1CLET (kcV/nm)
103 104
Fig.3. Plot of tlie relative biological effectiveness (RBE) for inaclivationof D. radiodurans as a function of LET.
O
•a|
Q
40
30 -
20 -
10 -
V,
.....
X
•<••:•' an
• •;•-. i >m
-,--• i n
•M-: ^ ! : : . - • • - : • { • { • ! • : « !
• - - • • • • : • : : : : ^ • • • : • • 1 : • ! + : : : • • •
. ; , ' • ; ri'.i ; • • • . • - ; • ; . , ' ; ; : : • • • •
\-\\\w\\ *-:-ri?:"i
• • { • • ! ; : - ; : ! . - • • ; • • ! - , • : : ; ; ; • • • •
: • • • : • ! :
••'. ••.'.•\'.}i) ; - • •
<—<••*• ' • ( ' . ? ' . ' '.-••
• •i ' { ' M i ; ; , j - - -
» , . , . . . . - . . . . . .
• i i-{-n r'f •: • •
..;.i.:,u;o.i-• . : • : • : - • • < - ; - • • • - • •
• ! • { • ; { . i \ - • ^
• • i i i l l .
X electron
• He
O c
• Ne
• Ar
• Nl
A Xe
O Au
1 10 10z 10J 104
LET (kcV/nm)
Fig.4. Plot of the dose at 10% survival as a function of LET.
- 4 6 -
JAKRl-Review ')?-() I1)
2 . 9 Mechanisms of the DNA Injury by Ion Beams and ItsRepair on Radioresistant Bacteria
— Analysis of Mutation Caused by Ion Beams UsingDNA Sase Sequence Methods —
Kazuki HARADA, Tatsuo NAKANO, Yurino OBIYA,Hiroshi WATANABE*, Yasuhiko KOBAYASHI*,Atsushi TANAKA* and Masahiro K1KUCHI*
Div. ofMol. Life Sci., PL Botanical last., PL Gakuen Women's Jr. College, and*Biotec. Lab., Takasaki Radiation Chemistry Research Establishment, JAERI
Introduction
We have been investigating the effects ofheavy ion beamson plasmid DNAin "TIARACooperative Research"0 in succession to"The Inter-University Collaborative Re-search Project with JAERI" in respect to thepresence of mutational hot spots on DNAbase sequences. The part of the results wasalready reported at "4th TIARA ResearchReview Meeting". In this paper, we reportedthe progression and principle of new hot spotassay system. As the new assay method,we arc conducting the in vivo study of themutation induced by heavy ion beams inmammalian cells using a transgenic mouse.
Experiments
A shuttle vector plasmid pZ189 DNA,containing the pBR327 replication origin, theSV40 early region and the Eschericlua colisuppressor tRNA gene (supF), which servesas a mutagencsis target, was irradiated withhigh LET (linear energy transfer) radiationas described previouslyx). Boron neutroncaptured (BNC) beam (a-particles) generatedfrom 10B (n, a) 7Li nuclear reaction at KURin Kyoto University and some heavy ionbeams generated from AVF cyclotron atTIARA in JAERI-Takasaki and fromsynchrotron at HIMAC in NIRS were used.After then, supF gene was scquenccd bydidcoxy method.
Furthermore, we tried to use transgenicmice, that is HITEC (hypersensitive in vivotest of carcinogcnicity) mice. The transgenecontains the wild-type rpsL (streptomycin-sensitive) gene of E. coli in a form of ashuttle vector plasmid pML4 DNA (Fig. 1).
Results
Mutations induced by BNC beam (a-particlc) in supF region were mainly basesubstitutions, and about a half of themoccurred at four mutational hot spot positions(133, 139, 160 and 172). Among them,transversions of G:C to T:A werepredominant, followed by G:C to C:Gtransversions. In human cells, however,u-particlc-induccd base substitutions weremainly G:C to A:T transitions. Thesediscrepancies may be attribute to the differentmutagenic mechanisms in E. coli andcukaryotic cells (Table 1). As the plasmidpZ189 DNA was designed to reduce theproportion of large deletion mutations, thenumber of mutants with gross structuralchanges or double strand breaks may havebeen greatly underestimated.
Now, we are conducting heavy ion beamirradiation experiments using transgenicmice. In the measurement of somaticmutation induced by heavy ion beams, sinceit is very hard to extract target gene fromseveral organ and select mutated one, weuse transgenic mice that contains pML4
47
JAERl-Rcview 95-019
Apa LI Xba 1
msL
EcoR\
Table 1 Types of Base Substitutions Inducedby High LET Radiations in Plasmids
P;>se s:
tutions
:bs!i-
E. coli cells
BNCB
•c:cd (T- cl ic
Protons3 5
•!:;! su^l\lulior.i)
Human cells
a-particles4^
Km*Fig. 1 Schematic Diagram of Shuttle VectorPlasmid pML4 DNA
TransitionsG:C-A:TA:T-»G:C
TransiersionsG:C-»T:AG:C->C:GA:T - C:GA:T - T:A
Total
IK 26.8)11 ( 26.8)0 ( 0.0)
30 ( 73.2)17( 41.5)12 ( 29.3)1 ( 2.4)0 ( 0.0)
41 (100)
9( 20.5)S( 1S.2)1 ( 2.3)
35 ( 79.5)20 ( 45.5)10 ( 22.7)5( 11.4)0 ( 0.0)
44(100)
70 ( 78.7)70 ( 78.7)0( 0.0)
19 ( 21.3)S( 9.0)
10 ( 11.2)1( 1.1)0( 0.0)
89(100)
plasmid carrying rpsL gene as a marker gene.This rpsL gene is expressed in E. coli andtransforms streptomycin resistant cell tostreptomycin sensitive. After the transfcctionof streptomycin resistant E. coli with pML4digested from gcnomic DNA and then ligatcd,E. coli can form colonies on agar plate withstreptomycin if it contains a pML4 with aninactive rpsL. Thus we can easily selectthe mutated pML4 carrying inactive mutationon rpsL region. Furthermore, it is expectedthat some deletions induced by heavy ionbeams arc observed by this assay system.
Acknowledgments
We arc grateful to Dr. Takeo Ohnishi(Nara Medical University) and Dr. YoichiGondo (Tokai University) for providing uswith biological materials and for theirtechnical teaching. We arc also grateful toMrs.Noriko Shindo (M. A.) for her constantlykind encouragement during this study.
References
1) K. Harada, T. Nakano, H. Watanabe, Y.Kobayashi, A. Tanaka and M. Kikuchi,TIARA Annu. Rep. 1993, 52-54 (1994).2) Y. Gondo, Y. Ikeda, Y. Motcgi, A.
Takcshita, M. Takahashi, K. Nakao and M.Katsuki, Environ. Mut. Res. Commun. (inJapanese), 16, 53-65 (1994).3) K. Takimoto, K. Yamamoto, T. Sagaraand K. Ishizaki, Mutation Res., 254, 1-9(1994).4) A. Jabcraboansari, W. C. Dunn, R. J.Preston, S. Mitra and L. C. Waters, Radiat.Res., 127, 202-210 (1991).
Publication
1) T. Nakano, K. Okaichi, K. Harada, H.Matsumoto, R. Kimura, K. Yamamoto, S.Akasaka and T. Ohnishi, "Mutations of ashuttle vector plasmid, pZ189, in Escherichiacoli induced by boron neutron captured beam(BNCB) containing a-particles", MutationRes., DNA Repair, 336,153-159 (1995).
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JAERI-Rcvicw 95-019
2 . 1 0 Optical Study of Hemoglobin in Red Blood CellsIrradiated with Ion Beams
Katsuhiko ADACHI. Takashi FUJIMURA. Hideki OMICHI. HiroshiWATANABE, Makoto TAKOI*, Masashi FUKAWA*, HarumichiKOBASHI*, and Mamoru TAMURA**
Department of Materials Development and Biotech. Lab., Takasaki, JAERI,* Department of Chemistry, Gunma University, and**Institute of Electricity, Hokkaido University
Introduction
Because light beam in the VIS and Near IRregions has relatively good property ofpenetration into living tissues, optical study inthese wavelength regions could afford directinformations about physical or chemicalbehavior of some biological substances invivo. We have started spectroscopicinvestigations in these regions in order todetect radiation effect on native hemoglobin inanimal red-blood cells.'-2)
A previous report showed a preliminaryresult that irradiation of He2+ ions gives riseto the formation of methemoglobin (MetHb)from oxyhemoglobin (HbC>2) in the redhemocytes of a rabbit.2) We continued furtherstudy to examine radiation effect on the red-blood cells using several kinds of ion beamswith different energies and various beamcurrents for different irradiation times. Thisreport gives results using He2+-ion beams asirradiation source.
Experimental
The irradiation target used was rabbit red-blood cells on a quartz plate. Separationprocedures of the cells were the same asdescribed previously.2) A 0.01-ml solution ofHbC>2 (0.1 g/ml) was spread on the quartzplate in ca. 1-cm2 area. The thickness was ca.0.06 mm after vaporization of excessmoisture in air. Irradiation was performed in
He gas atmosphere at room temperature usingan irradiation apparatus for seed (IAS) settledat a vertical beam port of the AVF cyclotronof JAERI, Takasaki.3) The energies of He2+ions used were 20, 50, and 100 MeV. Beamcurrent and irradiation time were controlled in10-6-10 nA range and for 1-3 min,respectively. After the irradiation, the samplewas dissolved with 1.2-ml saline (pH 7.3) ina rectangular quartz cell or disposable onemade of PMMA. Spectra in the 500-850 nmrange were measured using the YunisokuUSP 410 spectrophotometer as describedpreviously.2)
Results and Discussion
Figure 1 exemplifies spectra obtained forthe red-blood cell suspensions after theirradiation with 20-MeV He2+ ions for threeirradiation times at the beam current of 1 nA.All these are the difference spectra betweenthe irradiated and nonirradiated samples. Theabsorption bands at 540 and 576 nm due toHbC>2 decrease and concurrently the bandsaround 500 and 630 nm due to MetHbincrease. Additional absorbance contributes tothe back-ground level in the wavelenghregion shorter than 650 nm and thecontribution tends to become remarkable forthe longer irradiation times. It has beenobserved separately in the red-bloodsuspensions that the absorbance level in the700-850 nm decreases much to the minus
- 49 -
JAERI-Review 95-019
when hemolysis occured. In Fig. 1,however, no such a great decrease of the levelis observed, so that although the cellmembrane would suffer from the irradiationdamage, the hemolysis occures little at thistime for the spectral measurementimmediately after the irradiated samples weredissolved in the buffer. The absorbancechange in the short wavelength region wouldbe due to a little deformation or coaggurationof cells associated with denaturation of cellmembrane and/or proteins. Irradiation of the50- and 100-MeV ion beams resulted insimilar spectrum changes as those in Fig. 1.
Under the present experimental conditionsfor spectral measurements in light-scatteringsystems we can only compare quantitatively aratio of absorbances measured within thesame spectrum with those of other spectra.Net absorbance changes (<dOD's) of HbC>2and MetHb were measured at 576 and 630nm, respectively, relative to the absorbancelevel of the isosbestic point at 588 nm. Figure2 shows the conversion efficiency of MetHbfrom HbC>2 at several beam currents. The
efficiency in the reaction HbC>2 -* MetHb
was estimated by (^IOD63o/z]£63oV(^l
OD576/z]£576), where zle^ was the
difference extinction coefficient between
HbO2 and MetHb at X nm; i.e., e(MetHb) -
e(HbO2). we used AEsie = -11.7 mM-icm-i
and z]£63o = 3.6 mM-icm-M) Since theexperimental errors were large for weakabsorbance changes, then values of theefficiency could not be obtained accurately atlow beam currents (10-6-10-4 nA). All valuesobtained are less than unity and tend todecrease with the increases of the beamcurrent and irradiation time. This feature isapproximately similar to those for the cases of50- and also 100-MeV ion irradiations. Thus,even in the irradiation of He2+ ions with lowcurrents and for short times, the conversionefficiencies of the MetHb formation are lessthan unity. On the other hand, it has been
-0.5
He2+(20MeV)1 nA irrad.
I I I
500 600 700 800Wavelength/nm
Fig. 1. Difference absorbance spectra for the red-
blood cell suspensions dissolved in pH 7.3
phospatc-buffered saline containing \%
heparin after the irradiation with 20-MeV Hc2+
ions at 1 nA. The spectrum of nonirradiatcd
sample was used as reference. The irradiation
times are indicated in the figure.
co
coo
0.5 -
0
•
- •
*•
I l l l j
o•
He2+(20MeV)
n o• D
11 min I3 min 1
ml i |11 ml i 11
O
umil i
1 1 Hil l 1
-
o "
;, Mini I
0.001 0.1 10Beam Current /nA
Fig. 2. Conversion efficiency from HbC>2 to MetHb
in the irradiation with 20- McV He2+ ions at
several beam currents. The irradiation times are
given in the figure.
already found by us that the gamma-rayirradiation with a low dose leads to theformation of MetHb with unit efficiency.5)This difference would be due mainly todifference in LET; a high value for the ionand a low value for the gamma ray. That is to
- 5 0 -
JAERl-Review 95-019
say, probably because oxidative productssuch as OH radicals are produced with a highdensity inside the cells by the ion-beamirradiation, MetHb produced once and/or itsprecursory intermediates would be convertedsuccesively to any other products by furtheroxidation reactions.
References
1) T. Fujimura, N. Isnihara, H. Watanabe,H.Omichi, H. Kobashi, and M. Tamura,JAERI TIARA Annual Report 1992, 2,57-58 (1993).
2) K.Adachi, T. Fujimura, H. Watanabe,
H.Omichi, M. Fukawa, H. Kobashi, andM. Tamura, JAERI TIARA Annual Report1993, 3, 56-57 (1994).
3) Y. Kobayashi, M.Kikuchi, A. Tanaka, T.Shimizu, and H. Watanabe, JAERITIARA Annual Report 1992, 2, 27-30(1993).
4) O. W. van Assendelft, W. G. Zulstra,Anal. Biochem., 69, 43-48 (1975).
5) K. Adachi, T. Fujimura, H. Omichi, H.Watanabe, M. Fukawa, M. Takoi, H.Kobashi, and M. Tamura, The 37thSymposium on Radiation Chemistry,Sapporo, Abstr. No. 2010, 129 (1994).
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JAERI-Review 95-019
3. Radiation Chemistry
3.1 The Distribution of the Micro Chemical Structural Changes
induced in Polymer by Ion-beam Irradiation
Y.Hama, K.Hamanaka, H.Matsumoto, T.Takano, H.Kudoh,
T.Sasuga and T.Seguchi 55
3.2 LET Effects of High Energy Ion Beam Irradiation on Polysilanes
S.Seki, S.Tagawa, Y.Yoshida, H.Kudoh, M.Sugimoto,
T.Sasuga, T.Seguchi and K.Ishigure 57
3.3 Effect of Radiation Quality on Radical Formation in
Ion- irradiated Solid Alanine
H.Koizumi, T.Ichikawa, H.Yoshida, H.Namba, M.Taguchi and
T.Kojima 59
3.4 The Ion Beam Radiolysis Using the JAERI-AVF Cyclotron
- The Time Resolved Luminescence Measurement System-
Y.Aoki, M.Taguchi, H.Namba, R.Watanabe, Y.Matsumoto,
K.Kirnura and K.Ushida 62
3.5 Radiation Effects of Ion Beams on TCNB in PVA Films (II )
M.Taguchi, Y.Matsumoto, H.Hiratsuka, H.Namba and
Y.Aoki 65
3.6 Microdosimetry with Heavy Ions (in )
H.Namba, M.Taguchi, K.Furukawa, Y.Aoki and S.Ohno 68
3.7 Characteristics of Various Film Dosimeters for Ion Beams (ID )
— Design and Development of Dosimetry System for
Irradiation of Film Dosimeters —
T.Kojima, H.Sunaga, H.Takizawa and H.Tachibana 71
- 5 3 -
JAERI-Revicw 95-019
3 . 1 The Distribution of the Micro Chemical StructuralChanges induced in Polymer by Ion-beam Irradiation
Yoshimasa Hama1, Kenichi Hamanaka1, Hideya Matsumoto1,Tomoharu Takano1, Hisaaki Kudolr, Tsuneo Sasuga:,Tadao Seguchi2
'Advanced Research Center for Science and Engineering,Waseda University, 2JAERI, Takasaki Radiation ChemistryEstablishment.
1. Introduction
It has been found in ourproject that the depth distributionof the chemical structural changesinduced in some polymers by heavyion-beam irradiation are ratherdifferent from that of the stoppingpower of the ion-beam estimated byTRIM code, especially for multiplecharged ion-beam. This may be importantfor understanding the relationshipbetween the chemical reaction processand the energy transfer in polymeron ion-beam irradiation.
2. Experimental
The sample used in this workwas low density polyethylene (LDPE).This sample was formed in a slab of2mm thick by hot press.
Irradiation was carried out invacuum with AVF cyclotron (TIARA) atJAERI, Takasaki Radiation ChemistryEstablishment. The kind of ions usedwere lOMeV and 20MeV H*, lOMeV D*,20MeV 'He2*, 220MeV 12C5\ lOOMeV V ,160MeV 16O6\ 350MeV 2ONe8\ 175MeV 4OAr8\and 330MeV 40Arn*.
The depth profiles of thechemical structural change inducedin the slabbed LDPE by ion-beamirradiation were observed with micro-FT-IR system.
3. Results and discussion
Figure 1 shows the depthprofile of the infrared absorptionspectrum (964 cm"1) due to the trans-vinylene groups induced in LDPEirradiated by 220MeV 12C5*. The IRabsorptions due to the carbonyl groupsand the -OH groups also were observedand showed the same depth profilesas that of the trans-vinylene groups.The depth profile shown in Fig.lresembles the Bragg curve. However,the relationship between the depthprofile of the absorption and thatof the stopping power estimated byTRIM code is rather different forvarious ion-beams as shown in Figs.2and 3. In Fig.2, both ranges for
Fig.l. Depth distribution of theIR absorption (964 cm"1) due tothe trans-vinylene for LDPEirradiated to 500 kGy by 220 MeV12C5*
- 5 5 -
JAliRi-Rcvicw 95-019
20MeV He2* obtained from the absorptionand from TRIM code do not seem to bediffrent remarkably, but the peak ofthe absorption appears at nearer depthto the surface compared with thepeak of the stopping power. On theother hand, on irradiation of 175KeV'<0ArB* as shown in Fig. 3, the rangeobtained from the absorption isremarkably different from that fromTRIM calculation, though thedifference between both peaks of theabsorption and the stopping power is
not so large. Such appearance wasconfirmed for all kinds of ions.These facts suggest that there aremany problems in calculating thestopping power for multiple chargedheavy ion, e.g. the relationshipbetween the energy and the charge ofthe heavy ion in solid on calculatingthe stopping power. Moreover, therole of the secondary electrons shouldbe considered in the chemical reactiongiving variouj chemical structuralchange.
CUMGy(Absorptlon)—A— 0.5MGy(Absorp!lon)- O - I.OMGy(Absorptlon)
TRIM
50 100 150 200Depth(nm)
250 300 350
Fig.2. Depth distributions of the IR absorption due to the trans-vinyleneand the stopping power calculated by TRIM code for LDPE irradiated by 20MeV 4He3*.
0.10 -
0.00100
Depth(nm)150
" 3500—O- 500KGy(Absorplion)-A— 500KGy(Absorpllon)- O - 300KGy(Absorpllon)
100KGy(Absorpllon)Belhe(18Belho(8+THIM
Fig.3. Depth distributions of the IR absorption due to the trans-vinyleneand the stopping power calculated by TRIM code and Bethe formula for LDPEirradiated by 175 MeV 40Ara*.
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JAERI-Rcview 95-019
3 . 2 LET Effects of High Energy Ion Beam Irradiation on Polysilanes
Shu SEKI, Seiichi TAGAWA, Youichi YOSHIDA,Hisaaki KUDOH*, Masaki SUGIMOTO*.Tsuneo SASUGA*, Tadao SEGUCHI*,Kenkichi ISHIGURE**
The Institute of Scientific and Industrial Research, Osaka University.*JAERI, Takasaki**Department of Quantum Engineering and System Science, Faculty ofEngineering, The University of Tokyo.
Polysilane derivatives have attracted polystyrene calibration standards. The PMPS
great interest as a new category of polymer samples were dissolved in xylene and spin-
materials1. We have already reported on the coated on Si wafers. The thickness of the films
transient species and the electronic properties of was 0.5 u.m. These films were irradiated by 2
polysilanes, employing electron beam pulse MeV H + and He+ ion beams from a Van de
radiolysis spectroscopy2-3. Silicon containing Graaff accelerator6 and 10-45 MeV H + ion
polymers and their reactions induced by beams from TIARA cyclotron accelerator in a
electron beam irradiation play a significant role vacuum chamber (<10-6 Torr) at room
in two layer resist processes which is one of the temperature. Ion beam irradiation was done at
most important future technologies of electron the Research Center for Nuclear Science and
beam microlithography1-4. In addition, Technology, University of Tokyo for Van de
polysilanes may play an important role in ion Graff and at JAERI, Takasaki for the cyclotron,
beam lithography, a technology which is
receiving renews interest as a candidate for the
manufacture of semiconductors in the future5.
Poly(di-n-hexylsilane) ; PDHS was
prepared by the reaction of methylphenyl-
dichlorosilane with sodium in refluxing
toluene. The reaction was carried out under an
atmosphere of predried argon. The chlorosilane
was purchased from Shinetsu Chemical Inc.,
and distilled prior to use. The molecular weight
of PMPS sample was measured by gel
permeation chromatography (GPC) with
tetrahydrofuran (THF) as eluent. The PMPS
After irradiation, molecular weight distribution
of irradiated PDHS films was measured by gel
permation chromato-graphy : GPC system with
polystyrene cariblation standards
The loss of kinetic energy of ions in
traversing the PMPS thin films was estimated
by the TRIM 91 code.
It was already confirmed that the polymer
gel was generated for several kinds of a few
MeV order ion beams. The changes of
molecular weight distribution are shown in Fig
1 for the irradiation of 2 MeV He+ ion beam to
PDHS at room temperature. Apparently,
used in this experiment has bimodal molecular molecular weight of the polymer was increased
weight distribution, and the high or low
molecular weight peak was cut off by filtration.
The samples had their molecular weight of 1.1 x
with the ion beam irradiation, growing into
polymer gel. The irradiated polymer films were
developed and the fraction of generated gel was
104 and 5.6 x 105, respectively, determined by estimated as a function of the ion beam
- 57 -
JAERl-Rcview 95-019
fluences. According to the statistical theory of
crosslinking and scission of polymers induced
by radiation, the behavior of gelation is
expressed by the following equation
(Charlesby-Pinner relationship)7-8,
s + s1/2 = po/qo + m / qo(Mn)oD,
s = 1 - g,
where po is the probability of scission, qo the
provability of crosslinking, s the sol fraction, g
the gel fraction, m the molecular weight of a
unit monomer, (Mn)o the number average
molecular weight before irradiation, and D is
absorbed dose. And then, each G-value is
related to the values of po and qo as follows,
G(x)=4.8xlO3xqoG(s) = 9.6xlO3xpo
where G(x) is the G-value of crosslinking and
G(s) is the G-value of main chain scission. With
these equations, crosslinking and scission G-
values are calculated to be 0.67 and 0.39,
respectively.
Fig. 2 also shows the changes of
molecular weight distribution with the
irradiation of 20 MeV H+ ion beam. The
shoulder in the low molecular weight region
(around 104) raises with the irradiation, which
is proof of the main chain scission. The G
values of crosslinking and main chain scission
are also evaluated by the next formula in this
case of high energy proton irradiation. Then,
1/Mn = l/(Mn)o + (po - O.5qo) D/m,
1/MW = l/(Mw)o + (O.5po - qo) D/mG(x) and G(s) resulting to be 0.0029 and
0.204, respectively.However, the ion beam induced
molecular weight change are quite unique inboth cases in comparison with 7-rays whichcause simple increase of poly-dispersity. It isconsidered that the ion beam irradiation isheterogeneous, and the reactions bringing
10' 10'
Molecular Weight
Fig. 1 Changes in molecular weight distribution of poly(di-n-
hexylsilane) with 2 MeV He+ ion beam imidiation
Molecular Weigh!
Fig. 2 Changes in molecular weight distribution of poly(di-n-
hexylsilane) with 20 MeV He+ ion beam irradiation
molecular weight change are occurred at the
inside of ion trucks along the ion projectiles.
The sizes of ion trucks can be estimated by the
values of ion fluences where the overlap of the
trucks are observed. In these cases, the values of
10 ± 8 A and 36 ± 20 A are obtained as the
radius of 20 MeV H+ and 2 MeV He+ ion trucks
for the crosslinking and/or main chain scission
reactions.
References1 Miller, R. D.; Michl, J. Chem. Rev. 1989,89,13592 Ban, H.; Sukegawa, K.; Tagawa, S.
Macromolccules 1987, 20,17753 Ban, H.; Sukegawa, K.; Tagawa, S.
Macromoleculcs 1988,21, 454 Bowden, M. J. ACS Symposium Series 266;
American Chemical Society; Washington DC;1984; p.39.
5 Taylor, G.N.; Wolf, W.W.; Moran, J.M. J. Vac. Sci.Technol. 1981, 19, 872.
6 Kouchi, N.; Tagawa, S.; Kobayashi, H.; Tabata, Y.Radiat. Phys. Chem. 1989, 34,453.
7 Charlesby, A. Proc. R. Soc. London Scr. A, 1954,222, 60; 1954, 222, 542; 1954, 224,120.
8 Charlcsby, A.; Pinner, S. H. Proc. R. Soc. LondonSer. A, 1959,249, 367.
- 58 -
JAERl-Rcvicw 95-019
3 . 3 Effect of Radiation Quality on Radical Formation in Ion-Irradiated Solid Alanine
Hitoshi Koizumi, Tsuncki Ichikawa, Hiroshi Yoshida,
Hidcki Namba*, Mitsumasa Taguchi*, Takuji Kojima*
Graduate School of Engineering, Hokkaido University and
*Takasaki Radiation Chemistry Establishment, JAERI
IntroductionEffects of radiation quality on chemical
reactions arc due to difference in local dosedistribution. Reactive intermediates arcproduced with a spatial distribution accordingto the local dose distribution. If the reactionprobability of the intermediates depends ontheir concentration, the reaction productsdepend on the radiation quality. We arcaiming to clarify the relation among theradiation effects on organic solids, the localdistribution of the intermediates in the solids,and the radiation quality. Ion beams are usefulto this subject. The local dose distribution forion beams is much different from the
distributions for Y-ray and fast electrons. Thedistribution can be varied with changing theenergy and the species of the ions.
We have previously investigated radicalformation in alaninc irradiated with 0.5-3MeVH+ and Hc+ ions[l, 2], 175McV A$+ and460McV Arl3+ ions[2]. In this work, wehave investigated the radical formationirradiated with 220McV C+ ions. We havecompared the results with those for the otherions.
ExperimentalSamples used arc alaninc film dosimeters
of 0.22mm thickness. The dosimeters havebeen developed in JAERI[3]. They contain4()vt% of low-density polyethylene as binder.Irrac 'ation was carried out at the HX1 port inTIARA. Eight pieces of the sample films (ca.8mm X 15mm) were put one over another oneach sample holder in a vacuum chamber.220McV C^+ ions were generated with theAVF cyclotron, and the ions were irradiated tothe samples at ambient temperature. Thecurrents of the ion beams were measured witha Faraday cup on the holder plate just beforeand after the irradiations. ESR spectra of theirradiated films were measured with X-band
spectrometers at JAERI Takasaki and atHokkaido University. Radical concentrationswere calculated by double integration of theESR spectra and they were calibrated withDPPH as a reference.
Results and DiscussionsWith irradiation of alanine at room
temperature, stable neutral radicals arcgenerated through deamination anddccarboxylation of originally generated ionradicals. The yield of the neutral radicals(number of radicals per ion) in the alaninefilms irradiated with 220MeV C^+ ions areshown in figure 1. The yield in each film ofthe piled samples is shown as a function ofion fluence (number of radicals per unit area).The radical yield in the eighth film isnegligible, and is not shown. The energy ofthe ion in each film is shown in table 1. Theyield is constant below a critical fluencc, anddecreases at higher fluenccs. The criticalfluence is independent of the ion energy, and
isl-2 x 1()11 ions cm"3. Above the criticalfluence, the yield decreases with increasingion fluencc. This arises from overlap of theion tracks, which enables the intcr-trackcombination the radicals to occur. The radiusof the ion tracks is estimated from the criticalfluence to be ca. 18nm. The radius is betweenthe radius of 4-6nm for ().5-3McV H+ andHe+ ions[l, 2] and the radius of 40-60nm for175MeV and 460McV Ar ions[2]. Thisdifference in the radius arises from thedifference in local dose distribution in iontracks. Radial dose distribution in ion tracksof C ions is shown in figure 2. They arecalculated with equations proposed byChattcrjec ct al.[4, 5] The radius at the dose of50kGy will be a measure of the track radius.
The radical yield fory-irradiation decreasesabove the critical dose of lOOkGy because of
- 5 9 -
JAHRI-Review 95-019
o•3
3
Fluence / ions cm-2
the combination reactions between theradicals: the region produced through theoverlap of the region higher than 50kGyexceeds the critical dose. The radius is 2-6nmfor 10-220MeV C ions. Tin's value is betweenl-3nm for the H and He ions and 10-2()nmfor the Ar ions. The radius hence reflects thelocal dose distribution in the ion tracks.
Table 1. Initial and final energy of Cions(incidcnt energy of 220MeV) in each filmof the piled alaninc film dosimeter.
Film Energy of the Ions / McVInitial Final
12345678
2202001791561299652
2001791561299652
0
108
10"
104
102
10°
io-2
-
-
c-
__,10McV
1 SOMcV\ lOOMeV
K|-150McVpi 220McV
V x
x' \
ion
\
\
50kGj •
-
-
\ '
-
lO"1 10"r/m
10" 10'-
Fig.2. Radial dose distribution in ion tracks ofC ions calculated with equations proposed byChattcrjcc ct al.(rcfs. 4 and 5).
Fig.l. Radical yield in alaninc film dosimeter irradiated with 220MeV C ion as afunction of ion flucnce; the yield in the first ( O ) . l n e second (Q) , the third ( • ) , theforth ( B ), the fifth ( A ), the sixth ( A ), and the seventh (<> ) films.
- 6 0 -
JAERI-Revicw 95-019
10 r
1
-
-
- 0•••
I
1 1 1 1 1 1 1 I 1 1 1 1 1 1 1
3MeV a 220McV
O 2McV
OlMcVO 0.5McV
• 3MeV
0.5 Me VH ion • • 1 M e VHe ionC ionAr ion
1 i I i • 1 11 I i • f I I I
-
d60McV :
•175Mev"
-
.1 , i i0.10.1 1 10
<LET> / McV m g ' WFig.3. G-valucs of the neutral radicals in ion-irradiated alaninc as a function of averageLET(<LET>); H ions ( O ) , He ions ( £ ) , Arions ( • ) and C ions ( • )•
G-value of the radicals can be estimatedfrom the constant yield at the low fluenccs. Infigure 3, G-values for the C ion (sum of theyield in the seven films) and for the H, Heand Ar ions[l, 2] are shown as a function ofaverage LET(<LET>) during the path of theions in the sample. The yield for H and Heions tends to decrease with increasing<LET>. However, the yield for Ar and C ionsis not on the same G-valuc versus <LET>curve.
The G-valuc is shown in figure 4 as afunction of local dose. The local dose(<dosc>) in ion tracks is calculated with asimple cylindrical model, where the ionenergy is uniformaly distributed in acylindrical ion track having a length of the ionrange and a radius estimated from the criticalflucncc. Apparently there is a correlation: theG-values decreases with decreasing <dose>.
The dependence of the yield of the neutralradicals and their precursor ion radicals fory-irradiation on dosc[6] is shown in figure 4 forcomparison. The efficiency of the formationof the neutral radicals and their ion radicalsdecreases at the high doses because of thedecay of the radicals through combinationreactions. The G-valucs of the neutral radicalsfor the ion irradiations drop on the curve ofthe ion radicals rather than that of the neutralradicals. This indicates that the dependenceof the G-valuc on the radiation quality is
10°
Fig.4. The G-values in fig.3 as a function oflocal dose (<dosc>) calculated with acylindrical model (sec text). The dependenceof the yield of the neutral radicals (- -) andof the ion radicals ( -) for g-irradiation ondose arc plotted for a comparison.
primarily determined by the efficiency of thecombination reactions between the precursorion radicals. On the radiolysis of ion beamsthe ion radicals arc densely generated in iontracks at once, so that some of the ion radicalscombine with each other to disappear.However, on the radiolysis of low-LETradiation at 300K the ion radicals arcconverted to the neutral radicals before theother ion radicals are generated.
References
[l]Krushev, V.V., et al. Radial. Phys. Chem. 44,521-526 (1994).
[2]Koizumi, H., et al. in TIARA Annual Report1993, JAERI1994-005 (1994) pp.68-70.
[3]Kojima, T., Ranjith, H.L.A., Haruyama, Y.,Kashiwazaki, S. & Tanaka, R. Appl. Radial, hot.43,41-45(1993).
[4]Chatterjee, A. & Schaefer, H.J. Radial. Environm.Biophys. 13,215-227(1976).
[5]Magce, J.L. & Chatterjee, A../. Phys. Chem. 84,3529-3536 (1980).
[6]Koizumi, H., Ichikawa, T. & Yoshida, H., to bepublished.
- 61 -
JAHttl-Review 95-019
3 . 4 The ion beam radiolysis using the JAERI-AVF cyclotron- The time resolved luminescence measurement system -
Yasushi Aoki. Mitsumasa Taguchi. Hideki Namba. Ritsuko Watanabe.Yuuichi Matsumoto, fKazuie Kimura and fKiminori UshidaJAERl-Takasaki Department of Radiation Research for Environment andResources, tRIKEN
The effects of radiation quality hasbeen one of important problems to resolvenot only in radiation chemistry but also inhealth physics and in medical and industrialapplications of radiation. In the radiolysiswith y-rays and with energetic electrons, therate constants for various reactions, theeffects of solutes, the effects of solvents etc.are well-established up to present time,based on the experimental and theo-reticalworks. However, in the case of radiolysiswith charged particles like heavy ions, thekinds and the yields of products areunpredictable probably because huge energycould be deposited in much localizedvolume in the materials, compared with thatin the radiolysis with y-rays and electrons.
In order to elucidate the differencein chemical reaction mechanism due to theradiation quality, we are planning toinvestigate the whole radiation chemicalprocess induced by high energy heavy ionsbased on experimental observation ofreactive species and reasonable estimationof energy deposition in material, taking intoaccount diffusions of the reactive speciesand energy transfer reactions.
In this fiscal year(1994), time-resolved luminescence measurement systemhas been constructed at the port HX-1 of theAVF cyclotron in TIARA of JAERI-Takasaki. Here we introduce the systemwith its characteristics obtained by meas-urement of F+ center luminescence ofA12O3. In all experiments, 175 MeV40Ar8+ beam with the accelerating fre-quency in the cyclotron of 15 MHz was usedand the beam pulses were reduced to 1/5 or1/6 by the chopping system (S-chopping)installed near the exit of the cyclotron.
Fig. 1 shows the diagram of system,which is composed of beam pick-up partand optical measurement part. The pick-upsignals are obtained by detection ofsecondary electrons emitting from a carbonfoil (15ug/cm2 thick) on passing through outof accelerated ions. The electrons aredetected at the angle of 45 degree to thebeam direction and a two-stage-microchannel plate with a single anode(F4655, HAMAMATSU) is used as thedetector. The signal is drawn via C-coupling and amplified by a preamplifier(C5594, HAMAMATSU) whose frequencybandwidth and gain are 50 k to 1.5 G Hz and36dB (Voltage gain of x 63), respectively.After eliminating the noise pulses by aconstant fraction discriminator (583,ORTEC), the time correlation with the rf-signal for the beam chopping system (S-chopping) by a time to amplitude converter(567, ORTEC), adjusting the time delay ofthe rf-signal with a gate and delay generator(416A, ORTEC). The time correlation dataare accumulated with multi-channelanalyzer (MCA98B, Labo:) in pulse heightanalyzing mode to get time distribution ofthe secondary electrons from the carbonfoil.
In the beginning, we used a carbonfoil with the effective area of 25mm<|) indiameter and the detection angle of 60°.The separation between the center of thefoil and the microchannel plate was about150 mm. With this setting, we got a timedistribution of secondary electrons includingsome slow, low energy, electrons whichcould be easily eliminated by applying arepulsing voltage of 50 V in front of themicro channel plate. The best time
- 62 -
JAERI-Rcvicw 95-019
out in
Fig. 1 The diagram of time resolved luminescence measurement system at HX-1 port of AVF cyclotron.
distribution has the FWHM of 8.6 ns. Afterthe improving of this system with changingthe effective area to 10mm<j) in diameter, theseparation to ca. 50mm, and the detectionangle to 45°, the FWHM has become to 4.5ns.
Fig. 2 shows the rate of pick-upsignal as a function of DC current of Arbeam expressed in the rate of fluence. Itindicates a good linearity, up to 1 x 106 Ar
s/se
c
• * - •
3ou
3OO
o.3i
S.
106
105
104
IOJ
10'
1 1
••
••
1 1
103 104
••
•
1
io5
1
••
•
1(»61 1
107 10."
1 1
• • •
-
-
10" 1010
particle current (Ar /sec)
Fig. 2 The correlation between pick-up count rateand Ar ion beam current.
/sec, of pick-up count with ion beamcurrent, indicating that only one Ar ionexists in every counted bunch. However,there is nearly 1 order difference betweenthe values of pick-up count and of particlecurrent, probably because the efficiency inthe detection of electrons for beam pick-upis around 10%. Furthermore, constant pick-up counts above 108 Ar/sec is reasonabllyunderstood. Probably, every bunch has Arions, so if detection efficiency is 100%,every bunch will be counted. But thesaturated value(600 kcps) is much less thanAr pulse frequency (3 MHz). If thedetection efficiency is 10% for one Ar ion,the saturated value will show bunches withmore than two Ar ions are detectable in oursystem. But, it is possible that thesaturation will come from the detectionlimit due to the dead time of themicrochannel plate.
The time resolved luminescencemeasurement on the target of poly-crystalline A12O3 (AF995R, Desmarquest)has been done with three kinds of measuring
- 6 3 -
JAIiRl-Review 95-019
system. (1) photon counting system usingphotomultiplier tube (H3177, HAMAMA-TSU) and correlation with S-chopper signalin the same way of the pick-up system. (2)real-time direct observation system byphoto-
26000c3CJ
T3 4000CD
> ,
i>
c 2()(Kitu
U
cS "
1 1 I 1
-
" 1
I 175 MeV "Ar ' .VII1MII/
IA1..I). Cr ."Onm
-
'•' 4 7 ns!
_
500 100(1channel number
Fig. 3 The time priolile of F^ center luminescence ofAI2O3 irradiated with 175 MeV Ar ions from JAERI-AVF cyclotron
multiplier tube (H3378, HAMAMATSU)and integration of signals by a digitalstorage oscilloscope (TDS540, Tektronix)and (3) streak camera system (C2830,HAMAMATSU). In these three measure-ments, the S-chopper signal was used as areference time for the beam (t=0). Thewavelength region for measurement wasselected by an interference filter for (1) and(2), or a spectrograph (HR320, Jobin-yvon)for (3).
Fig. 3 shows the measured timeprofile of F+ center luminescence inducedby irradiation of 175 MeV Ar ions, as atypical responce function of the lumines-cence measuring system of (1). The timeresolutions were 4.7, 10.2 and 5.5 ns forsystems (1), (2) and (3), respectively. For(3), the entrance slit of steak tube wasrelatively wide to weak light, so it ispossible to get higher resolution with abetter arrangement of optical devices suchas lenses. For all systems, since data wereaccumulated for more than hundreds ofpulses, the contribution of time jitter of ionpulses to the measured resolution, seems notso trivial to neglect. Then using the pick-up signal for start of the measuring systems,
instead of the S-chopper signal, should beneeded to get a better time resolution. Inthe next term, we will try to develop thesystem for time resolved optical absorptionmeasurement, especially for liquid samples,with increasing beam current on the targetand with making delicate arrangement oflight path to the detector etc.
- 64 -
JAERl-Revicw 95-019
3 . 5 Radiation Effects of Ion Beams on TCNB in PVA Films(II)
Mitsumasa TAGUCHI1, Yuuichi MATSUMOTO2, Hiroshi HIRATSUKA2,Hideki NAMBA1 and Yasushi AOKI1-lTakasaki Radiation Chemistry Research Establishment, JAERI2Dcpartment of Chemistry, Gunma University
l.IntroductionIt is supposed that the heavy ions irra-
diation induces a local energy depositionin the target materials, which makes atrack along an ion trail. To obtain theinformation of the track structure wehave studied absorption spectra and itsfluence dependence of TCNB(tetracya-nobenzene) in PVA[poly(vinyl alcohol)]film irradiated with heavy ions.
By measurements of UV-VIS absorp-tion spectra after the irradiation, TCNBanion radical that has a long lifetime ofhours at room temperature was ob-served. Furthermore the dependence ofthe production of the TCNB anion radi-cal on the fluence was examined fordifferent fluence. We investigate theradii of tracks and the energy densities inthe tracks produced by the heavy ionsirradiation.
2.ExperimentalSamples used were PVA films doped
with TCNB for UV-VIS absorptionmeasurements. The size of sample filmwas lxl cm2 square and 300 |U,m thick.The concentration of TCNB in PVA filmwas about 13 mM. Ions for irradiationwas C5+(220 MeV, 120 pA), Ar11+(330MeV, 80 pA) and Ar8+(175 MeV, 25 pA)in EA-BRACHI2) connected to AVFcyclotron in TIARA. The fluence de-pendence of the production was meas-ured by the irradiation for different irra-diation time. The sample films wereplaced on a holder in a vacuum chamber
in less than 5xl0~7 Torr. As a reference,sample films were also irradiated by 60Coy-ray and electron beam(2 MeV, 1 mA).Absorption spectra of sample filmsbefore and after the irradiation wererecorded on a Shimadzu UV-2200 spec-trometer in air. The irradiation and themeasurements were carried out at roomtemperature.
3.Results and DiscussionFigure 1 shows UV-VIS absorption
spectra of TCNB in PVA film irradiatedwith C5+ and Arll+ ions. The band ob-served in the shorter wavelength regionthan 330 nm is due to the parent, and inthe longer wavelength region newabsorption bands produced by the irra-diation were observed. There are somepeaks, e.g. at 377, 438 and 464 nm, forboth ions-irradiation. In comparisonwith results of y-ray and electron beamirradiation, the latter bands are assignedto TCNB anion radical. The latter bandsare, however, weak in the case of Ar8+
ion irradiation and back-groundabsorption was increased in comparisonwith C5+ ion irradiation. This differenceshould be due to a carbonization ofPVA film induced by high energydeposition(2900 eV/nm) of Ar8+.
The fluence dependence of a yield ofTCNB anion radical can be examined bymeasuring the absorption differencebetween before and after irradiation.Figure 2 shows the plot of 464-nmabsorption difference between before and
- 65 -
JAERI-Rcvicw 95-019
uCO
.aotn
XJ<
400 500Wavelength / nm
Figure 1. Absorption spectra of TCNB inPVA film irradiated with C5+ ions(a) andAr11+ ions(b).
after irradiation against the fluence forArll+ and C5+ ions. The yield increasedwith the fluencc in the low fluenceregion and then reached maximum, final-ly decreased gradually. The maximumvalues were observed at 6xlO10 ions/cm2
for C5+ ions, and at 2xlO9 ions/cm2 forAr11+ ions that is about 30 times as C5+
ions.In order to understand the fluence
dependence of the radical yield,TCNB anion radicals are supposed to beproduced in each tracks of the heavyions, these tracks were overlapped in thehigh fluence region. It is assumed thatTCNB anion radicals were changed tofinal products via excitation or ionizationin consequence. It is supposed that thestructure of the track is cylindrical andthe energy density in the track is homo-geneous for simplicity. As results of a
T • 1
radius of track.: 18nm
10 20 30FLUENCE/1010 ions/cm2
0.03 (b) radius of track -: 130nm
20 „ 40FLUENCE /108 ions/cm2
Figure 2. Fluence dependence of the464-nm absorption difference of TCNBin PVA film between before and afterirradiation for C5+(a) and Ar11+(b) ions.
simulation based on the above assump-tion, fluence dependence of relativeabsorbance were obtained on the differ-ent radii of the track. The radius of thetrack has been estimated to be 18 nm,being in good agreement with the exper-imental results for C5+ ion irradiation asshown by solid line obtained by thesimulation in Figure 2(a). The radius oftracks was obtained as to be 130 nm forAr11+ ion irradiation as shown in Figure2(b).
The radii of penumbras estimated bytheoretical calculation were 4.5 |nm and1.6 |iim for C5+ and Ar11+ ions, respec-tively,3) and are 1 to 2 order(s)bigger than the radius obtained by thesimulation. In order to understand thedifference of these radii of the tracks, we
- 6 6 -
JAERI-Review 95-019
10i-4p
11+ :
102
Radius / nm
Figure 3. Initial average energy densitiesobtained by theoretical calculations forC5+ and Ar11+ ions.
calculate the average initial energy densi-ties in the track for each ions.3) Figure 3shows the results of the calculation forthe initial average energy densities. It isunderstood from the graph that theenergy densities in the track obtainedfrom the simulation are higher than 10"3
cV/nm3 level, though a little differenceis present between C5+ and Ar11+ ions.This level is nearly equal to 100 G; .This should indicate that TCNB anionradicals could be produced in the regionwith higher dose than the above in thetrack.
Referencesl)H.Hiratsuka et al. JAERI TIARA
Annual Report,66-67,3(1993).2)H.Namba et al. JAERI TIARA
Annual Report,163-166,l(1992).3)J.L.Magee and A.Chattcrjee,
J.Phys.Chem.,3529-3536,84(1980).
- 6 7 -
JAERl-Revicw 95-019
3 . 6 Microdosimetry with Heavey Ions (III)
Hideki Namba, Mitsumasa Taguchi, Katsutoshi Furukawa2,Ynsushi Aoki nnd Shin-ichi Ohno3
JAERI, Takasaki, Biotech. Lab., JAERI, Tokai, Lascr-Chem. Lab.2,Tokai Univ., Inst. Res. Develop.3
I. IntroductionIrradiation with high energy heavy ions
gives rise to ununiform energy depositionto the materials to make so-called "trackstructure". Ionizations and excitations bythe energy deposition will be successive tothe direction of incident ions, however,there exist very large dependence of dis-tance from the incident ions to the verticaldirection of incident ions. This is mainlycaused by secondary electrons produced byincident ions. These secondary electronsare produced by electronic excitationprocess that is the main process for theenergy deposition by high energy heavyions. It is very important for the radiationchemists to get the information of energydeposition around the ion beams in order toclarify the "chemical effects" followed bythe energy deposition. However, there areonly a few research works to investigate theenergy deposition directly because ofexperimental difficulty.
We have installed an experimentalapparatus for basic study on radiationchemistry with heavy ions ( EA-BRACHI ) at HX1 port of AVF cyclotronin TIARA,^ and started to measure thespatial distribution of energy deposition togaseous Ar induced by high energy Ar ionbeams.2>3^ In this paper, we report theabsolute dose measurement near the rangeor "cut-off limit" of secondary electrons.
II. ExperimentalThe experimental apparatus for this re-
search is essentially the same as we havereported before.2'3^ Heavy Ar ion beam( 175MeV ) from the cyclotron are intro-duced to the EA-BRACHIa) through abending magnet of HX1 port connected to avertical beam port in Second Heavy IonIrradiation Room. EA-BRACHI hasdifferential pumping system with turbo-molecular pumps, tantalum collimatorsand pressure control system. It is possibleto control the pressure in the third chamber
with this system during ion beam irradia-tion.
Gaseous Ar is introduced to the thirdchamber with controlling its flow rate bymass-flow controller ( MKS 147B ). Thepressure of the gas is measured with pres-sure sensors ( MKS Baratron 122A and127A), and controlled with pressure con-troller ( MKS113A ) by pumping throughthrottling valve ( MKS 253A-2-4CF-2 )connected to the turbo-molecular pump( Osaka Vacuum TG1000M ) in the thirdchamber.
Ar ion beams from AVF cyclotron wereintroduced to the third chamber of EA-BRACHI. The beam monitoring and posi-tion setting were done as described before2).The ion beam was introduced through thecollimator (0.1mm ) connected to the thirdchamber. Two small ionization chamberswere set on a stage, which arc possible tomove all directions with an accuracy of5[im. Ionization current induced by Ar ionbeam was measured by two electrometers( Keithley 617 ) connected to the collectingelectrodes of ionization chambers. D.C.voltage was supplied to the high voltageelectrode from high voltage power supplies( Hamamatsu C3350 ). The signals weretransferred by an optical fiber to the neigh-boring operation room, and were accumu-lated by a computer ( NEC PC9801NA )with 10 times sampling after the currentbeing steady state.
The intensity of the incident ion beamhas fluctuation during the irradiation, there-fore, the beam intensity was monitored bymeasuring the ion beam intensity at thethird collimator with another electrometer( Keithley 617 ) and calibrated with therelationship between the collimator beamcurrent and incident ion beam through thethird collimator.
III. Results and DiscussionFig. 1 shows the applied voltage de-
pendence of relative ionization current in-
- 68 -
JAKRI-Review 95-01')
duccd by 175McV Ar beam irradiation in7.6 torr Ar gas at 41.5mm, 56.5mm,71.5mm, and 130mm from the beam center,respectively. The relative ionization currentmeans the ionization current induced by theion beam per incident ion beam current( dimension less ). The applied voltageregion about 70V, the ionization currentbecame constant ( saturation region ),whereas the ionization current increasedrapidly at more higher voltage. The valueof the saturation current is decreasing withincreasing the distance from the cinter ofthe incident ion beam. The current corre-sponds to the amount of ions producedinside of the ionization chambers.
The density of the water ( lg/cm3 ) isusually used as a standard because it is themain component of living body. The dis-tance from the ion beam reduced to the unitdensity, R ( nm ), is expressed with thedistance from the ion beam in gas at densityp, Rp ( nm ).
R = Rp-pg/pr (1)
where p t is the density of the gas and p. is
D= 1.6 X l(rlf> L
unit density ( lg/cm3).
The dose at distance R, D ( Gy ), is ex-pressed as follows;
l,V-p -K
Where I is ionization current measured bythe mesh ionization chamber, I; is beamcurrent of incident ion, Z is charge of incid-ent ion, V is a volume of mesh ionizationchamber, Wc is W-valuc of gaseous argon,and K is transparency of mesh ionizationchamber. The dose distribution curvearound with 175McV Ar8+ ion beam ob-tained with equation 2 is shown in Fig. 2.
The amounts of produced ions werepredicted^ to be proportional to reciprocalsquare of the distance ( r ). The dotted linein the figure indicates the curvature of r~3
and r"4. The solid line in the figure is theresult of the least square fitting: the bestfitting was r~3fl. The icsults obtained inthis paper and our former papers2"3) indicatethat the amount of energy deposited aroundthe ion beam gradually shift from r~2
dependence to more sharp decrease withincreasing the distance from ion beam.
The absolute dose value, 2.9Gy at745nm, agrees with our former experimen-tal results obtained with Tandem accelera-tor in Tokai Research Establishment5) andtheoretical calculations^.
cCD
I4"TON"c
CD
CD
Applied Voltage (V)100 1000 2000
Distance from Ion Beam (nm)
Fig. 1. Applied voltage dependence ofinduced ionization current.
Fig. 2. Saturation current at differentdistances from the center of ionbeam.
6 9 -
JAERI-Rcvicw 95-019
Reffcrences 4)R. Katz, B. Ackerson, M. Homayoonfor1)H. Namba, Y. Aoki, M. Taguchi and K. and S. C. Sharma, Inactivation of cells by
Furukawa, experimental apparatus for heavy ion bombardment, Radiat. Res.,basic radiation chemistry with heavy ion 47, 402 (1971).beams, JAERI TIARA Annual Report 1, 5)K. Furukawa, S. Ohno, H. Namba and M.163(1992"). Komaki, Proceedings of the 35th Sym-
2)H. Namba, M. Taguchi, K. Furukawa, S. posium on Radiation Chemistry, Japan,Ohno and Y. Aoki. Microdosimctry with 167 (1992).heavy ions, JAERI TIARA Annual 6)J. L. Magee and A. Chatterjce. TrackReport 2, 69 (1993). reactions of radiation chemistry. Kinetics
3) H. Namba, M. Taguchi, K. Furukawa, Y. of nonhomogcncous process (J. Wiley &Aoki and S. Ohno. Microdosimetry with Sons), edited by G. R. Freeman, 171heavy ions (II), JAERI TIARA Annual (1987).Report 3, 71 (1994).
- 70 -
JAERI-Review 95-01')
3 . 7 Characteristics of Various Film Dosimeters for Ion Beams (III)— Design and development of dosimctry system for irradiation
of film dosimeters —
Takuji KOJIMA, Hiromi SUNAGA, Haruki TAKIZAWA.and Hiroyuki TACHIBANAAdvanced Radiation Technology Center, JAERI
I. IntroductionAbsorbed dose is a common measure for
interpretation and comparison of radiationeffects of ion beams on organic materialsand biomaterial samples. Characteristics ofdose distribution in materials especially fordepth profile is also vital for them.
We have started development of ion beamdosimetry techniques using a simple current(charge) monitoring system and several thinfilm dosimeters of about 10 to 200 | m inthickness which are well established both for60Co-gamma rays and electron beams ofenergies from 0.15 to 3 McV. Study on doseresponse characteristics of film dosimetersand development of depth dose profilingtechnique with high spatial resolution havebeen preliminarily carried out for ion beamsfrom the AVF cyclotron in TIARA1'2* usingalanine-PE3), Gaf4*, Radiachromic(RCD)5),and cellulose-triacctate(CTA)6) dosimeters.
In these irradiation experiments, a thick
graphite plate placed at downstream of ionbeam path was used as both an absorber forcurrent monitoring(in terms of charge) andalso a mount of irradiation samples.However, rcproducibility of monitoring wasnot sufficient to meet our purpose since thismonitoring system might be influenced byinsulation property of irradiated dosimetermaterials, secondary electrons escaped fromthe absorber surface, contamination of thesame m/q particles, and backscattcring andspattering of incident ions, etc..
A total absorption calorimeter which isalmost independent of above influences, wasapplied to estimation of resultant uncertaintyin measurement of incident charge, undersimultaneous irradiation with a Faraday cupin the wide uniform irradiation field. Oncethe uncertainty in charge measurement isestimated by the simultaneous irradiation, aFaraday cup can be used for calibration offilm dosimeters in a stack condition
<SYSTEM> <SIMULTANEOUSMEASUREMENT>
<PURPOSE>
TOTAL ABSORPTIONCALORIMETER
FARADAY CUP
FILM DOSIMTERS
ENERGY PERUN1 IT AREA
PARTICLEFLUENCE
ABSORBEDDOSE
UNCERTAINTY ESTIMATIONFOR FLUENCE MEASUREMENT
DOSIMETER CALIBRATION(LET DEPENDENCE STUDY)
DEPTH-DOSE PROFILING
Fig.l A combined dosimetry system
- 71 -
IM-RI-Review
simultaneously irradiated and/or profiling ofradiation field through accurate calibrationof dose response of film dosimeters. Thesimultaneous irradiation method also enablesus to reduce uncertainties due to instabilityof ion beam parameters.
From this point of view, we designed anddeveloped a combined dosimctry system asshown in Fig,. 1, and a simultaneousirradiation apparatus which arc attached tothe "wide-area ion irradiation chamber"7'.
II. A combined dosimctry systemA total absorption calorimeter allows us to
measure energy fluence, absorbed energy perunit irradiation area. Aluminum was selectedas the absorber material to give sufficientlymeasurable temperature rise with shortirradiation time and to minimize radiation-induced activation by ion beams. Theabsorbers consists of a 30 mm diameterplate and a fcrrule(2.5 mm in diameter, 5mm in length) behind the plate. Four platesof 0.5, 1, 2, and 3 mm thickness wereprepared correspondent to different ionranges. The temperature rise in the absorberis measured by a high-accuracy thermistor(head size of 1 mm diameter) imbedded ina ferrule part of the absorber which isconnected with a thermometer recorder(Technol Seven D632). Temperature rise byion beam irradiation is usually controlledwithin about 5° C.
The designed Faraday cup consists of a130-mm long cup with a graphite absorber(40 mm in diameter and 30 cm in thickness)and a high-voltage suppression elcctrodc(40mm in diameter, 30 mm in length). Thedigital electron current intcgrator(ORTEC439) was used to measure integrated charge.Uncertainties in charge measurement wasestimated by simultaneous irradiation of theFaraday cup with the calorimeter throughapertures of the same squarc(7.1 cm2), asshown Fig.2, on the basis of calibratedenergy of incident particles.
Characterization of ion-beam doseresponse of thin film dosimeters such asalaninc-PE, RCD, Gaf, and CTA can bealso performed by their simultaneousirradiation, as shown in Fig.3, with theFaraday cup monitoring well-established bycalorimctry.
HI. Results and discussionIn advance to irradiation experiments, thecurrent(chargc) measurement system wascalibrated using a standard current supplier(Kcithley Picoampcrc source 261). Theobtained uncertainty in charge measurementin 7.1 cm2 square was within in a few nClevel, although there was a constantbackground signal of about 0.03 nA. Tominimize this contribution down to a fewpercent, we irradiated ion beams up to a few|.iC as a total charge.
ION H U M S D
D
C A L O R I M E T E R
( T E M P E R A T U R E - R I S E
M E A S U R E M E N T )
FARADAY CUP
(CHARGE M E A S U R E M E N T )
Fig.2 Simultaneous measurement using acalorimeter and a Faraday cup in uniform-flucncc field
ION B E A M ST H I N F I L M D O S I M E T E R S
0 h FARADAY CUP(CHARGE M E A S U R E M E N T )
Fig.3 Irradiation of film dosimeters inuniform-fluencc field based on real-timemonitoring by a Faraday cup
- 7 2 -
JAORI-Rcvicn 95-019
Irradiation experiments using the abovecombined dosimctry system were carried outin scanned beams field of 100x100 mm for20 McV proton and 220 McV carbon beams.The currents of both beams measured in the7.1 mm2 square were about 20 nA.Suppression voltage of -100 V was appliedfor both ion beams.
Measured value of accumulated charge fora few minutes, which result in about a fewj.iC as a total, was compared with a nominalvalue estimated by an energy analyzer. Aspreliminary results, estimated values forproton and carbon beams were agreed withnominal values within ±0.8% and ±0.1%,respectively. The results showing potentialityof accurate beam current monitoring lead usto improve reliability in studies oncharacteristics of film dosimeters bysimultaneous use of this charge measurementsystem.
IV. SummaryFor improvement of reliability in study on
characteristics of various film dosimeters,we designed and developed a combineddosimctry system consisted of a totalcalorimeter, a Faraday cup, and thin filmdosimeters, and a simultaneous irradiationapparatus of film dosimeters. As preliminaryresult using 20 McV proton and 220 McVcarbon beams, we confirmed that the systemhas potentiality to measure beam currentaccurately. Further study using other ionbeams is in progress on dose responsecharacteristics of film dosimeters based onthe reliable beam monitoring.
AcknowledgementThe authors wish to thank H.Kudoh and
R.Tanaka of JAERI for their valuablediscussion on design of a combineddosimctry system for ion beams.
Referencesl)T.Kojima, H.Sunaga, H.Takizawa and
J.Okamoto:JAERI-M 93-241(1993) 652)T.Kojima, H.Takizawa, H.Tachibana
and H.Sunaga:JAERI-M 94-005(1994) 743)T.Kojima, A.Ranjith H.L., Y.Haruyama,
S.Kashiwazaki and R.Tanaka:Appl.Radiat.Isot., 44, (1993) 41
4)R.D.H.Chu, G.Van Dyk, D.F.Lcwis,K.P.J.O'Hara, B.W.Buckland and F.Dincllc:Radiat.Phys.Chcm., 35(1990)767
5)W.L.McLaughlin, A.W.Boyd, K.H.Chadwick, J.C.McDonald and A.Millcr:"Dosimctry for radiationprocessing"(Tailor & Francis, London,1989) 167
6)H.Sunaga, R.Tanaka, K.Yoshida, andI.Kohno:RIKEN Acccl.Prog.Rcp., 22(1988) 130
7)T.Sasuga, H.Kudo and T.Seguchi:JAERI-M 93-047(1992) 117
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JAERl-Rcview 95-019
4. Organic Materials
4.1 High Energy Ion Irradiation Effects on Polymer Materials (in )
H.Kudoh, T.Sasuga and T.Seguchi 77
4.2 Heavy Ion Irradiation Effect on Light Absorption of
Polymer Films
T.Arakawa, N.Kasai, S.Yamamoto and T.Seguchi 80
4.3 Ion Track Copolymer Membranes Consisting of
Diethyleneglycol-bis-allylcarbonate and
Acryloyl-L-proline Metyl Ester
M.Asano, M.Yoshida, H.Omichi, N.Nagaoka, H.Kubota,
R.Katakai and K.Ogura 83
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JAERI-Review 95-019
4 . 1 High Energy Ion Irradiation Effects on Polymer Materials(III)
H.Kudoh, T.Sasuga, T.Seguchi
Takasaki Radiation Chemistry Research Establishment, JAER1Takasaki, Gunma, 370-12 Japan
1. IntroductionFor the evaluation of radiation resistance of
polymer materials applied in space environ-ment and nuclear facilities, ion irradiationeffect on polymers have been studied. Theirradiation effects were investigated on thepoint of linear energy transfer(LET) ofpolymers in terms of changes in mechanicalproperties such as elongation and strength atbreak, and always compared with electronbeams or gamma-rays irradiations 1>2'3). It wasfound that there seems to be little or no LETeffect for various polymers such as polycthyl-ene(PE), polytctrafluoroetylene(PTFE), poly-mcthylmethacrylate (PMMA), epoxy matrixresin in glass fiber reinforced plastics(GFRP)for protons of 10-45MeV and He2+ ions of20-50MeV. Similar results were observed forother polymer materials in other studies. Onthe other hand a few polymers such as poly-cthcrsulphonc(PES) and Uderpolysulphone(PS) showed a significant LET effect2),however, these polymers were found to beaffected by the polymer's temperature duringirradiation of gamma-rays or electronbeams3).
In this report, the high LET ion effect, that is,heavy ion irradiations effect on polymers aredescribed. The heavy ions are C5+, O5+, Aru+,and polymers of PE, PTFE, PES, and Cellu-lose tri-acetate(CTA) as a dosimeter wereused. The discussion of LET effects by theseheavy ion irradiation is concentrated to thechain scission of PMMA in this report.
2. Experimental(1) Materials; PMMA of 3mm thickness
commercial glass grade was formed to thinfilm less than 0.01mm by casting in chloro-form solvent. CTA film dosimeter of0.125mm thick film was used as received fromFuji Photo film Co.Ltd.(2) Irradiation; An ion spot beam of 10 mmdiameter from TIARA Cyclotron acceleratorwas scanned uniformly to material in alOOmmxlOOmm area under vacuum. Thedetails of the ion irradiation procedure arereported elsewhere. The stopping power ofions to PMMA and CTA was calculated withthe TRIM code and the absorbed dose wasdetermined as the product of the stoppingpower and ion fluence. The stopping powerand range calculated by TRIM code are shownin Table 1. For determination of LET anddose, the stopping power was used at thesurface value for PMMA, and the averagevalue at surface and at 0.125mm depth forCTA.(3) Measurements; The molecular weight ofPMMA was measured by gelpermiationchromato-graphy(GPC) with chloroformsolvent. The optical density of CTA at 280nmwas measured, and the dose was calibrated bycompared with that of electron beam irradia-tion.
3. Results and discussionThe changes of molecular weight of PMMA
were determined by GPC measurements afterion irradiation. The number average molecularweight is plotted against dose in Fig.l. Thechain scission is relatively small for heavyions of C5+ and O5+. The chain scission proba-bility of PMMA, G(s), is calculated from Fig.l
- 7 7 -
JAERI-Rcview 95-019
data, and is plotted against LET(unit inkcV/j-im) as shown in Fig.2. The G(s) isalmost constant until around 15kcV/(im, thentends to decrease at higher LET. So, it seemsthat there is a threshold in LET. For CTA filmdosimeter, the abosorbance(at 280nm), which,is sensitivity as a dosimeter, after ions irradia-tions is also plotted to stopping power calcu-lated by TRIM code. In this case, the sensitivi-ty is almost constant until around 200McV.cm2/g(LET: 15keV/|am), then decrease athigher LET as same as PMMA in Fig.2.Therefore, if the G(s) of PMMA is normalizedby the sensitivity of CTA dosimeter for the allLET range, the LET effect on chain scissionmight be canceled.
Above analysis of LET effect is based on thecalculation of TRIM code. When the TRIMcode is applied appropriately for heavy ions topolymers, the LET threshold in Fig.2 could beexplained by the reaction mechanisms such ashigh density active sites reactions in an iontrack model or the overlap of the tracks bymulti-irradiations in the same position in thepolymer sample.
If the TRIM code for heavy ions is not ad-justed in polymer matrix, the actual energydeposition deviates from the calculation, then,the absorbed dose must be corrected accordingto the deviation.
In the research of profile analysis of productsin micro-area of ion beam irradiated polyeth-ylene by Hama group4), the double bondformation is rather well coincident with TRIMcode calculation for proton and Hc2+ ions, butis much deviated from the calculation forheavy ions as O5+, Ar8+ and Ar11+. The energydeposition occurs in wide range than theTRIM code calculation, then, the actual dosedeposited in an unit target polymer becomesmaller by 1/2 or 1/3 than the calculation.When these correction was applied to Figs.land 2, the G(s) should be almost constant forany LET, that is, no or little LET effect.
4. ConclusionHigh energy ion irradiation effects on
PMMA and CTA were studied by followingchanges in molecular weight and optical densi-ty. Both polymers showed little LET depend-ency below around lOkeV/um, but above thisthreshold value, the probability of chain scis-sion tends to decrease with increasing LET.When TRIM code calculation could be appliedto polymers for heavy ion irradiation, theobserved LET dependence might be explainedby the ion track or spur model. If TRIM codewas not applicable, the evaluation method forabsorbed dose determination should be de-veloped, then the LET effect become clear.
References1) H.Kudoh, T.Sasuga, T.Scguchi, andY.Katsumura, Polymer, submitted.2) H.Kudoh, T.Sasuga, and T.Scguchi,JAERI-M 93-241, 79, 19933) H.Kudoh, T.Sasuga, and T.Scguchi,TIARA Annual Report 1993(Vol.3), 794) R.W.Garrctt, D.J.Hill, T.T.Lec, K.A.Milnc,J.H.O'Donncll, S.M.C.Pcrcra, and P.J.Pomcry,"Radiation Effects on Polymers", ACSSymposium 475, Chapt.10,19914) Y.Hama, K.Hamanaka, H.Matsumoto,T.Takano, H.Kudoh, T.Sasuga, and T.Scguchi,TIARA Annual Report 1994 (Vol.4)5) W.Shunabcl and S.Klaumunzcr, Radiat.Phys. Chcm, Vol.37,131, 1991
- 78 -
JAERI-Review 95-019
Table 1 Stopping power(S: MeV cm2/g) of ions and the penetration range(R: mm) for PMMAand CTA
IonEnergy(MeV)
Stopping power(MeV cm2/g)
Range(mm)
PMMA
CTA
PMMACTA
H+
30
16.3
18.1
7.27.1
He2+
50
138
148
1.51.46
C5+
220
5701010*647969*
1.031.00
0 6 +
160
1616
18363190*
0.140.13
05+
100
24464010*27837380*
0.150.14
Ar11 +
330
8836
1005220900*
0.290.28
* average between ions incoming surface and outgoing surface with the thickness of samples.The others arc the value at ions incoming surface.
Dose(MGy)0 0.1 0.2
0
-0.04
-0.02
0.01 0.02D.ose (MGy)
0.03
Fig.l Change in number average molecularweight of PMMA
O ; Co Y-ray, Q ; H+(45MeV)• ; H+(30MeV), ± ; C
5+(220McV)A ; O5+(100MeV)
10-1 101
LET(kcV/fxm)Fig.2 G-valuc of chain scission, G(s),
for PMMA as a function of LET• ; this workO ; reported values taken from refcrcncc(5)
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JAERI-Revicw 95-019
4 . 2 Heavy Ion Irradiation Effect on Light Absorptionof Polymer Films
Tetsuhito Arakawa*. Noboru Kasai, Shun-ya Yamamoto, and Tadao Scguchi
Department of Material Development, Takasaki Radiation ChemistryResearch Establishment, JAERI* Faculty of Engineering, Tokai University
IntroductionPolymer films, which arc applied in satellite
as the covering materials, arc exposed to ionsand electrons. The changes of the physical andchemical properties such as a light reflectionor absorption arc induced by the exposure. Forthe evaluation of radiation resistance by ions,a heavy ion of Ni was irradiated and the lightabsorption was measured, and the changeswere compared with the electron beam irradia-tion.
ExperimentalMaterial: polycthylcnc-tcrcphtalatc (PET;
thickness 0.1 mm), polycthylene-naphtalate(PEN; 0.025mm), polybutylncnc-naphtalatc(PBN; 0.02mm), and polyethcrcthcrkctonc(PEEK; 0.006 mm) films were used, which areall transparency to visible light.
Ion irradiation: Nickel ion (N\4+) acceleratedto 15 McV by Tandem accelerator in TIARAwas exposed to each film under vacuum byspecimen scanning using a special apparatus^in Fig.l. The specimen, mounted on an alumi-num rotor of 50 mm diameter, is rotated andmoved repeatedly along the rotational axix.For the reference of ion irradiation, 2 McVelectron beam was irradiated under vacuum.The ion and electron irradiation conditions arcshown in table 1.
Measurement: The absorption of light forspecimen after and before irradiation wasmeasured by a photomcter(Beckman DU-65)in the range 200 nm - 900 nm at room tem-
perature in atmosphere.
Results and discussionThe dose absorbed in polymer film by ion
irradiation was calculated from the ion flu-ence/cm2 and stopping power of Ni ion usingTRIM codc(for PET, 1.9xlO4McV.cm2/g). Forelectron beam irradiation, the dose was evalu-ated by a film dosimeter of CTA, and thestopping power is 1.8 McV.cm2/g. Figure 2shows the spectra of absorption on PET filmsirradiated by Ni ions and electrons. The ab-sorption occurs mainly in the range of lowerwave length less than 500 nm, and themaximum at 300-400 nm. Though the absorp-tion spectrum is some different between Niion and electron irradiations, the absorbance at400 nm was plotted against absorbed dose forPET film in Fig.3. The absorbancc increaseslinearly with dose for both irradiations. ThePET film is 100 micrometer thickness, and theion penetration is only 6 micrometer, butelectron penetrates throughout the film. So,the absorbancc was compared by the normal-ized thickness by the ion penetration thick-ness; that is 6 micrometer. The absorbancc perdose is about 100 times larger in case of Niion than in electron irradiation.
In a case of electron irradiation, the absorb-ancc depends on the irradiation condition asthe absorbance increased with the higher doserate and decreased by irradiation in Heliumatmosphere, which is supposed to be dependedon the material temperature during irradiation
- 8 0 -
JAERI-Review 95-019
by beam heating.For PEN, PBN, and PEEK films, the absorb-
ance showed the same tendency; that is, thenbsorbnncy wns high by nbout 102 times in Niion irradiation compared with electron irradia-tion.
The increase of absorbancc at 300-400 nm inthese aromatic polymers is thought to due tothe formation of double bonds beside phenylgroup. In the study of gas analysis after radi-olysis for PET(2>, PEN(2\ and PEEK(3>, theproducts were carbon dioxide, carbon monox-ide and hydrogen.The LET in Ni4+(15McV) is calculated to be
104 times larger than the LET of 2McV elec-tron as seen in table 1. The absorbancc in highLET is about 102 limes. So, high LET radia-tion seems to induce the much of doublebond formation. In the radiation chemistry, itis supposed to be that the absorbed energy atphenyl group is delocalized so the chemicalreaction is much reduced. However, the depos-ited energy by high LET radiation may beenough large to induce the chemical reactionafter dclocalization at phenyl group. Theother mechanism is the thermal effect by beamheating. In the case of electron irradiation, theabsorbancc increases with temperature ofsamples during irradiation. The high LET ionbeam irradiation produce the beam heating inthe local area of sample because the polymermaterials are very low thermal conductivity.
ConclusionA heavy ion of 15McV Ni4+ irradiation effect
on phenyl polymer films was investigated bythe absorption measurement, and comparedwith the electron beam irradiation. The ab-sorbancc was about 102 times larger in Ni ionthan electron irradiation for all materials. Thebig difference between two irradiations isthought to be the LET effect and/or thermaleffect by beam heating. The irradiation tem-perature effect must be cleared by low LET
irradiation.
References(1) T.Sasuga.. S.Knwnnishi M.Nishii..T.Seguchi, and I.Kohno, Radiat.Phys.Chem.,Vol.37, pp.135-140 (1991)(2) T.Saito, T.Seguchi, and S.Nagano, andI.Omae, JAERI-M 89-096 (1989)(3) E.L.Hegazy, T.Sasuga, M.Nishii, andT.Seguchi, Polymer, 1992, Vol.33, pp.2896-2903
Fig.l Ni ion irradiation chamber attached at the
beam port of TANDEM accelerator
- 8 1 -
JAERI-Review 95-019
Table 1 Ni ion and electron beam irradiation conditions
Ni4+
Accelerated energyBeam current
Stopping powerPenetration depth (for PET)
Irradiation areaDose rate (Average)
15MeV5,6,10,20 nA
1.8XlO4MeV-cm2/g6 U m
62.8 cm2
1,1 kGy/s
2MeV4,6 mA
1.8 MeV • cm2/g8 mm
120cm beam scan5.0 kGy/s
3oCO
_<0MGy>
<EB 2MV 4mA>
5MGy1535
200' * ' ' .I «-•.,'-•,
400 600 800WAVELENGTH (inn)
J_L
D • -EB 2MeV,4mA,He A- • -Ni4+15MeV,5nA,VacuumeO- • -EB 2MeV,4mA,He <> • -Ni4+15MeV,6nA,Vacuume©•••EB 2MeV,6mA,He V-"Ni4+ 15MeV,10nA,VacuumeH • • -EB 2MeV,8mA,He ® • • -Ni4"1" 15MeV,20nA,Vacuume
Fig.2 Photo absorption spectra of PET
film (100 U m) by irradiation of 15MeV
Ni ion and 2MeV electron beams.
20DOSE (MGy)
dO40
Fig.3 The change of 400nm absorbance
on dose for PET film irradiated by Ni ion
and electron beams under vacuume.
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JAERI-Review 95-019
4 . 3 Ion track copolymer membranes consisting ofdiethyleneglycol-bis-allylcarbonateand
acryloyl-L-proline methyl ester
Masaharu Asano, Masaru Yoshida, Hideki Omichi, Noriyasu Nagaoka*,Hitoshi Kubota*, Ryoichi Katakai*, and Koichi Ogura**
Department of Material Development, Takasaki Radiation Chemistry ResearchEstablishment, Japan Atomic Energy Research Institute,
1233 Watanuki-Machi, Takasaki, Gunma 370-12, Japan, *Department of Chemistry,Faculty of Engineering, Gunma University, Kiryu, Gunma 376, Japan, and
**College of Industrial Technology, Nihon University,1-2-1 Izumi-Cho, Narashino, Chiba 275, Japan
INTRODUCTION
It is known that the latent tracks of heavyion particles passed through a polymer film ofdiethyleneglycol-bis-allylcarbonate (CR-39)leads to the formation of holes with a uniformsize by a chemical etching1-2. On the otherhand, a linear poly(acryloyl-L-proline methyl
3.0
2.5
2.0
I 1.5
1.0
0.5
0 I I I10 20 30 40 50
Etching time (minutes)60
Figure 1 Size of cone-shaped pores produced in poly(A-ProOMe/CR-39) films with compositions of (A) 0/100, (B)10/90, ( • ) 20/80, (A) 30/70, ( • ) 50/50, and (O) 70/30 wt %,etched in aqueous 6M NaOH at 60°C after a 11.5 MeV/n •'"Arion irradiation.
ester, A-ProOMe) is a polymeric gel whichshrinks above a critical temperature calledLCST and swells below the LCST. Acombination of A-ProOMe and CR-39 isexpected to movide an artificial intelligentvalve that would behave similarly to biologicalmembrane, particularly as an on-off switchdrastically responsive to a slight change of
CM
O
a,<u
Q
I I
0 10 20 30 40 50Etching time (min.)
60
Figure 2 Depth of cone-shaped pores in copoly(A-ProOMe/CR-39) films. The experimental conditions were the same asthose given in Figure 1.
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JAERI-Review 95-019
Figure 3 On-off switch function of intelligent cone-shaped pores in copoly(A-ProOMe/CR-39,60/40) film treated at temperaturesof (a) 0°C and (b) 30°C for 24 hours after pretreating with water at 0°C for 3 weeks. The ion beam irradiation and etchingconditions were the same as those given in Figure 1.
temperature.For this purpose, 100 |im thick
copoly(A-ProOMe/CR-39) films with desiredcompositions were prepared by means of a castpolymerization. The films irradiated with 40Arion were etchced with an aqueous NaOH, toevaluate the on-off switch function of pores.
EXPERIMENTAL
The CR-39 monomer containing 27 wt% isopropylperoxydicarbonate (IPP) as acatalyst was purchased from PPG Industries-Asia/Pacific Ltd. The A-ProOMe monomerwas synthesized by a condensation reaction intetrahydrofuran, as described elsewhere3.
The 100 u.m thick copoly(A-ProOMe/CR-39) films with compositions of 0/100,10/90, 20/80, 30/70, 50/50, and 70/30 in weightratio were prepared by means of castpolymerization. The polymerization wascarried out af 70°C for 24 h, using IPP as acatalyst (3 wt % in monomer).
The copolymer films of 40 mm x 40 mmattached to a glass plate of 50 mm x 50 mm x 1mm were irradiated with a 11.5 MeV/n 40Arion (fluence: 1 x 106 ions/cm2) under a vacuumof 10-7 Torr at the AVF cyclotron of TIARA.The films irradiated were etched in an aqueous6N NaOH at 60°C without stirring. After theetching, the films were washed with excesswater and lyophilized. The diameter andgeometries of ion track pores produced in thecross-section were measured microscopicallywith a Jeol JXA-733 scanning electronmicroscopy (SEM).
RESULTS AND DISCUSSION
The chemical etching of the irradiatedhomopoly(CR-39) film produced acharacteristic conical pore on both sides of thefilm. The pore size at the surface increaseslinearly with the passage of etching time andwith the introduction of A-ProOMe in the
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JAERl-Review 95-019
copolymer as shown in Figure 1.Figure 2 shows the depth of the conical
pore in the cross-section. Pore becomesshallow when considered with the sesult inFigure 1 by increasing A-ProOMe in thecopolymer film. In other words, theintroduction of A-ProOMe in CR-39 filminduces the decrease in sensitivity to '"'Ar ion.
Figure 3 shows the SEM photographsof copoly (A-ProOMe/CR-39,60/40 wt %) filmtreated at either 0°C or 30°C for 24 h afterpretreating with water at 0°C for 3 weeks. It isclear that the pore is closed at 0°C while it isopen at 30°C. This result is related to the factthat the poly(A-ProOMe) gel in water shows avolume phase transition around 14°C.Probably, the conical pore at 0°C is coveredwith a swollen A-ProOMe component. Onthe contrary, at 40°C a real cone-shaped porecould be observed, because of the geldeswelling.
REFERENCES
1. M. Tamada, M. Asano, R. Spohr, J. Vetter,C. Trautmann, M. Yoshida, R. Katakai, H.Omichi, Macromol. Rapid Commun., 16,47 (1995).
2. R.L. Fleischer, P.B. Price, and R.M.Walker,Nuclear Tracks in Solids,Principles and Applications, University of
• California Press (1976).3. M. Yoshida, H. Omichi, H. Kubota, and
R. Katakai, J. Intel. Mater. Sys. Struc,4, 223 (1993).
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JAERI-Review 95-019
5. Inorganic Materials
5.1 Low-temperature Electron-irradiation Damage and Recovery
in Boron-doped Graphite
A.Iwase, N.Ishikawa and T.Iwata, M.Watanabe and T.Nihira 89
5.2 Electron Irradiation Effects on Transport Properties
in EuBazCu30Y
N.Ishikawa, A.Iwase, K.Tsuru and O.Michikami 90
5.3 Low-temperature Irradiation of Refractory Body Centered
Cubic Metals
H.Tanimoto, H.Goto, H.Mizuhashi, S.Okuda, N.Ishikawa
and A.Iwase 91
5.4 Experimental Study on Proton and Helium Ion Irradiation
Damage of C/C Composite
S.Baba, M.Ishihara and M.Eto 94
5.5 Depth Profile of Damage Structures in Triple-beam
Irradiated Austenitic Stainless Steel
S.Hamada, Y.Zhang, Y.Miwao and D.Yamaki 96
5.6 Microstructural Evaluation of Single Crystalline Alz03
Irradiated with Triple Ion Beams
Y.Katano, T.Nakazawa, D.Yamaki, T.Aruga and K.Noda 99
5.7 Microstructural Studies of Ion-irradiated Ceramic Materials
H.Saka, K.Kuroda, K.Noda, Y.Katano and T.Nakazawa 102
5.8 Cascade Damage Formation by High Energy Self-ion Irradiation
N.Sekimura, J.Saeki, N.Ohtake, Y.Shirao, S.Okada,
Y.Kanzaki, S.Isino and R.Tanaka 104
5.9 Surface Nitridation by Ion Beam Irradiation and
Plasma Processing
M.Nunogaki, T.Okada, H.Takeshita, N.Aoki, S.Yamamoto
and H.Naramoto 107
5.10 Defect Formation in LiF Irradiated with 175MeV 40Ar Ions
Y.Aoki, S.Yamamoto, H.Takeshita, H.Naramoto, A.Osa,
N.Shigeta, M.Koizumi, H.Matsuoka and T.Sekine 109
5.11 Ti Ion Implantation into TiOz Rutile Single Crystals
N.Aoki, H.Takeshita, S.Yamamoto, P.Goppelt-Langer
and H.Naramoto 112
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5.12 Metastable Phase Formation by Ion Implantation (in )
- High Dose Implantation of Silver into Silicon—
H.Takeshita, N.Aoki, S.Yamamoto and H.Naramoto 114
5.13 Development of High-functional Fullerene Thin Films by
Ion Implantation
H.Koinuma, M.Yoshimoto, M.Sasaki, S.Ohashi, T.Asakawa,
H.Koyama, S.Gonda, T.Arakane, T.Shiraishi, H.Takeshita,
S.Yamamoto, Y.Aoki, P.Goppelt-Langer and H.Naramoto 115
5.14 Radiation Damages in Synthesized Silica Glasses
Induced by High Energy Fe Ions Irradiation
S.Nasu, S.Oonishi, K.Nishiwaki, R.Fujimori, H.Nanto, R.Yamamoto,
H.Takeshita, Y.Aoki, S.Yamamoto and H.Naramoto 118
5.15 In-situ Observation of Irradiation-induced Amorphization
in Transmission Electron Microscopy
H.Abe, H.Naramoto and C.Kinoshita 121
5.16 YBazCuaO* Films Irradiated by Mn+ Ions
Y.Kazumata, S.Yamamoto and H.Naramoto 124
5.17 Formation Process of Defect Clusters in MgAlz04 under
Displacive and Ionizing Irradiation
C.Kinoshita, K.Yasuda, H.Abe and H.Naramoto 126
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5 . 1 Low-Temperature Electron-Irradiation Damage and Recoveryin Boron-Doped Graphite
Akihiro Iwase, Norito Ishikawa, Tadao Iwata, Mitsuo Watanabeand Takeshi Nihira*Advanced Science Research Center, JAERI*Faculty of Engineering, Ibaraki University
As boron is thought to act as a substitutionalacceptor in graphite, boron-doping can cause adepression of the Fermi level and an increase ofhole concentration in graphite.
To study the effect of boron-doping onradiation damage in graphite, we performed thefollowing experiments; boron-doped graphitewas irradiated with 2.0 MeV electrons at 35 K.During irradiation, the electrical resistivitychange was measured as a function of electronfluence. After irradiation, the specimen waswarmed up to room temperature, and therecovery of the electrical resistivity wasmeasured. For comparison, electron irradiationand recovery measurement were alsoperformed in undoped graphite.
Figure 1 shows the electrical resistivitychange as a function of electron fluence forboron-doped graphite and undoped graphite.The resistivity change rate for boron-dopedgraphite is much smaller than that for undopedgraphite. This is one of the effects of theincrease of hole concentration by boron-doping. In undoped graphite, conductioncarriers are scattered by the irradiation-produced defects, resulting in an increase ofresistivity with increasing defect concentration.In boron-doped graphite, as a concentration ofcarriers(holes) is much larger than in undopedgraphite, the screening of the strain fieldaround the defects by carriers may reduce thesensitivity of the electrical resistivity to theirradiation-produced defects.
Figure 2 shows the recovery of the resistivityas a function of annealing temperature. Forundoped graphite, it is believed that theirradiation-produced interstitial atomsagglomerate and C2-molecules and theirclusters are formed around 100 K. Thisagglomeration causes a large reverse recoveryaround 100 K.
For boron-doping graphite, this reverserecovery almost disappears. The experimentalresult suggests that irradiation-producedinterstitials are trapped by boron below 100 K,and they cannot form C2-molecules or clustersaround 100 K.
1.22 electron fluence (xio16cm-2)
Fig. 1 Electrical resistivity change as a functionof electron fluenece for boron-dopedgraphite(open circles) and for nondopedgraphite(solid circles). Irrdaiation temperature is35 K.
E"10CJ
ato
IO
. ** *D
o
o1 0 100 200
Temperature (K)
Fig. 2 Recovery of electrical resistivity forboron-doped graphite and nondoped graphite.
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JAERI-Review 95-019
5 . 2 Electron Irradiation Effects on Transport Properties in
Norito ISHIKAWA, AMhiro IWASE,* **
Koji TSURU and Osamu MICHIKAMIAdvanced Science Research Center, JAERI*Electron Devices Laboratory, NTT Interdisciplinary Research Laboratories.**Faculty of Engineering, Iwate University
superconductingwith 2MeV
We i r radia tedcompound
electron and performed in-situmeasurement of transport propertiessuch as normal-state resistivity andsuperconducting critical current densityJ c . We prepared c-axis oriented
EuBa2Cu3Oy thin films which had Tc
values of about 83K. Irradiation wasperformed at about 100K in order tominimize annealing of irradiationinduced defects at higher temperature.Standard four-probe method was usedfor a measurement of resistivity.Normal-state resistivity monotonicallyincreased as increasing fluence. Fig.land Fig. 2 show current-voltage ( I-V )characteristics at 40K and 60K,respectively, in the field of 0T, IT, and6T before and after the irradiation. Ascan be seen in the figures, decrease of J c
was observed after the irradiation.Subtle change of curvature in I-V curvewhen 6T was applied to the sample at60K involves delicate problem of vortexglass transition. In order to furtherinvestigate irradiation effect on vortexglass transit ion, more rigoroustemperature control is needed[l].
Reference[llJAFendrich, WKKwok, J.GSapinizakis, C J.
van derBeek, VJVLVmokur, S.Fleshler, U.Welp,KKViswanathan and G.W.Crabtree, Phys.Rev. Lett, 74,1210 (1995).
I-V 40K
10"
CURRENT (mA)
Fig.l current-voltage characteristics at40K in the field of 0T, IT, and 6T beforeand after the electron irradiation.
I-V 60K
10
10- 1 10° 10CURRENT (mA)
10"
Fig.2 current-voltage characteristics at60K in the field of 0T, IT, and 6T beforeand after the electron irradiation.
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JAERl-Review 95-019
5 . 3 LOW-TEMPERATURE IRRADIATION OF REFRACTORY BODYCENTERED CUBIC METALS
Hisanori Tanimoto, Hiroyuki Goto, Hiroshi Mizubayashi,Shigeo Okuda, Norito Ishikawa* and Akihiro IwaseInst. of Materials Science, University of Tsukuba* Advanced Science Research Center, JEARI
INTRODUCTIONThe refractory body centered cubic
(bcc) metals such as Mo and W are ex-pected for structural materials offusion reactors. In spite of manyexperiments, however, the behavior ofself-interstitial atom (SIA) in thesemetals is remained as an open ques-tion. Since the experimental resultsreported are very complicated, dif-ferent models of SIA's are proposedbased on the specific aspects of theresults. In our recent internalfriction (Q"1) measurements of Moafter low-temperature 20MeV protonirradiations[1], the dislocationpinning by free-SIA's is found to becomposed of two constituents and thestrength of the relaxation peak dueto SIA's shows a saturation withincreasing Frenkel-defect concentra-tion (CFP). We conclude that thereexist two types of SIA's: One is the<110>-dumbbell SIA which undergo free-migration with rotation of the dumb-bell axis and the other the SIA with<110> symmetry of which migration isconstrained on a (110) plane or in a<110> direction due to no rotationalmode [1].
To pursue the further informationon SIA in bcc metals, we carried outthe Q"1 measurements of W after 20MeVproton irradiation at 5K [2]. Incontrast to Mo, all the dislocationpinnings show no temperature shiftwith CFP, suggesting that the defectcomplexes around cascade damagespossibly trap SIA's giving no free-SIA's in W after 20MeV proton irradia-tion. To clarify this issue, we car-ried out 2MeV electron irradiation,where only the Frenkel-pair defectscan be expected.
EXPERIMENTAL PROCEDURESStripes of 0.5x1.5x25 mm3 were cut
out from a W single crystalline rodpurchased from Metal Crystals & OxidesLtd. in England (residual resistivityratio more than 8000). One part ofthe stripes was shaped into a reed of0.1 mm thickness by using emerypapers. After shaping, the specimenswere chemically etched and annealed at2300 K in 10"9 Torr for 1 h.
A hand-made cryostat was set atthe end of the SX5 beam line inTIARA, JEARI Takasaki and the low-temperature irradiation of the Wspecimens was carried out by using2MeV electrons from the 3MV single endaccelerator in TIARA. The specimenafter irradiation at 5K was warmed upto 60 - 100 K with a rate about 1K/min, then cooled down to 5 K. Asequence of irradiation and warm-up/cocl-down was repeated with in-creasing dose. The Q"1 and the reso-nant frequency (f, f2~E, E:Young'sModulus) of the specimen were measuredby using the flexural vibration of thereed about 500 Hz. The temperaturewas monitored by a copper-constantanthermocouple near the specimen. Duringirradiation and warm-up/cool-downafter irradiation, the temperature,the Q"1 and the f were recorded inevery 30s.
RESULTS AND DISCUSSIONThe low-temperature irradiation
system set up enables us to performthe 2MeV electron irradiation below 5Kwith beam intensity up to 600nA/cm2
at the specimen. Here we report theresults of the Q"1 measurements withaccumulated dose below 5xl016 e/cm2.
Figure 1 shows the changes in f
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JAERI-Review 95-019
and Q-1 observed during the warm-upand subsequent cool-down runs afterirradiation at 5 K. It is noted thatf and Q"1 before the irradiation showsmonotonous decrease and increase withincreasing temperature (dashed linesin Fig.l), respectively. Except theso-called bulk effect, no changes in fand Q-i are detected during irradia-tion. During warm-up above 20 K afterthe irradiation, f and Q"1 showdeviatory increases and decreases fromthose observed before the irradiation.The increase in f and decrease in Q"1
observed during warm-up remain un-changed during the cool-down run. Thechanges in f and Q"1 during warm-upsuggest that SIA's migrate on todislocations and pin down them(dislocation pinning) above 20 K.
To see the changes in f due todislocation pinning more clearly, thetemperature derivatives of f(d(f/fo)/dT, where fo is f observed at5K before irradiation) are shown inFig.2. The peaks in the d(f/fo)/dTcurves suggest that intensive disloca-tion pinnings take place at around 20,30-38 and 45 K. All the pinnings showno shift to lower temperatures withincreasing CFP, suggesting that SIA'sresponsible for them should be re-leased from some traps at the pinning
temperatures. These behaviors of thedislocation pinnings are similar tothose observed after 20MeV protonirradiation (see Fig.3). The defectcomplexes are therefore presumablyformed below 20 K and serve as trapsof SIA's. In other words, because ofthe strong interaction betweenSIA's and irradiation-induced defects,almost all the SIA's are possiblytrapped by irradiation-induced defectsduring migration below 20 K. Thefurther information on SIA's can beexpected from the relaxation peak dueto SIA's which is now in progress.
REFERENCES1. H.Tanimoto, H.Mizubayashi, N.Tera-mae and S.Okuda, J. Alloys and Com-pounds, 211/212(1994)54.136.2. H.Tanimoto, H.Mizubayashi andS.Okuda, Proc. 1st Int. Conf. of UltraHigh Purity Base Metals, Kitakyushu-City (Japan), May 24-27, 1994, p.359.
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0.001 -
20 40 60 80
TEMPERATURE (K)
20 40 60 80
TEMPERATURE (K)
Fig.l (a) The change in the resonant frequency (f) observed duringwarm-up after 2MeV electron irradiation at 5K (dots) and subse-quent cool-down (dashed lines). The irradiation was repeated withincreasing dose (Frenkel-defeet concentration (CFP) for 1stirrad.:3x10"5, 2nd:2.5x10-4, 3rd:8.3x10-3, 4th:0.086 and 5th:0.78ppm). (b) Similar to (a) but those in the internal friction(Q"1).
33
•o
20 40 60TEMPERATURE (K)
Fig.2 Temperature derivatives off (d ( f / fo ) /dT, where fo is fobserved at 5K before irradia-tion) observed during warm-upafter 2MeV electron irradiationat 5K (dots in Fig.l(a)). Thedashed line "pre." shows thed(f/fo)/dT for f observed beforeirradiation.
•5*
' _ _ ' • • ' " ~ —
after 5th irrad.
. 4 th / " \ ^
' 3rd / " ^
1 2nd /
1st / s-—
' 1 1
I
i
i i
, • " • • • • * .
• * * , * • " * • * * " • * * . . .
T '%s*
0 20 40TEMPERATURE (K)
60
Fig.3 Similar to Fig.2 butobserved during warm-up after20MeV proton irradiation at 5K(CFP for 1st irrad.: 1.9xlO"4,2nd: 8.6xlO"4, 3rd:6xlO-3, 4th:0.035 and 5th: 0.23ppm).
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JAERI-Review 95-0)9
5 . 4 Experimental Study on Proton and Helium IonIrradiation Damage of C/C Composite
Shin-ichi BAB A, Masahiro ISHIHARA and Motokuni ETODepartment of High Temperature EngineeringEnergy Materials Development Laboratory, JAERI
Introduction
The carbon carbon (C/C)composite material is considered tobe used for the Plasma FacingComponent (PFC), such as the firstwall, divertor etc., in the fusionexperimental reactor ITER(International ThermonuclearExperimental Reactor) and JT-60U(JAERI, Tokamak-60 Upgrade),since the C/C composite is anexcellent material with high thermalconductivity as well as thermal shockresistivity. To clarify irradiationdamage induced by the D-T reaction(D+T —> * H e ( 3 . 5 2 M e V )+n(14.06MeV)) is one of the majorresearch subjects for the C/Ccomposite to be applied to the PFC.A high energy simulationexperiment by an irradiation ofprotons and helium ions was,therefore, carried out using AVFcyclotron facility.
Experiment
Irradiation specimens weremachined from a one-dimensionalC/C composite blocks, MFC-1manufactured by MitsubishiChemical Industries Co., Ltd. Disktype specimens with 8 mm indiameter and 1 mm in thicknesswere irradiated by 10 MeV protonsand 50 MeV Helium ions in avacuum of about 10"6 Pa at roomtemperature in AVF cyclotron.
After irradiation dynamic hardnessand laser Raman spectrum weremeasured.
The irradiation damage wasestimated by the EDEP-l(ext)codeO); irradiation damage by 10MeV protons and 50 MeV heliumions were 3X10"3dpa and 7X10"2dpa,respectively, and the maximumrange for protons and Helium ionswere 652u.m and 1030jim ,respectively at a density of 1.95g/cm3.
Results
Fig.l shows dynamic hardnessprofiles after 50 MeV helium ionirradiation. From this figure, wecan see the peak of the dynamichardness was observed around themaximum range estimated byEDEP-1 code; the peak of thedynamic hardness for 10 MeVproton was also observed around theestimated maximum range.However, the measured dynamichardness has a broad peak than theestimated one. In the calculation theEDEP-1 code treats a homogeneousmaterial, while the C/C compositeconsists of matrix region, fiberregion and voids; this might causethe broad dynamic hardness peak inthe experiment.
The laser Raman spectra forirradiated and unirradiatedspecimens are shown in Fig. 2. Thepeak of the first-order of Raman
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JAERI-Rcvicw 95-019
spectra is observed at two bands;1580 cm-1 and 1360 cm-1 which havebeen assigned to E2g and Aig modes,r e s p e c t i v e l y ^ ) . In a perfectcrystalline graphite, the Aig band isnot observed; this band becomesapparent only when the amorphous
content of the sample increases. Wecan find that the ratio, Aig/E2g, ofirradiated specimen is about 30 %higher than that of unirradiated one;the amorphous content of thespecimen would become higher bythe helium ion irradiation.
Distribution of Dynamic Hardness
calculated range : 1030 Jim
Calculated by EDEP-Kext)
Measured LineNumberDepth(um) from Surface of
Carbon/Carbon Composite(MFC-l) for- "Irradiated by means of
Cyclotron(TIARA) 50MeV Helium Ion
Fig.l Dynamic hardness profiles of C/C composite material for helium ion irradiated at 50 MeV
SOMeV Helium ionIrradiated Area
Fig.2 Comparison of intensity ratio(Id/Ig) of Raman shift for an unirradiated areaand helium ion irradiated area
Reference(1) T.Aruga, K.Nakata andS.Takamura, Nucl.Instr. and Meth.B33(1988)748.
(2) F.Tuinstra and J.L.Koenig.JChem Phys.53(3)l 126-1130(1970).
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JAERI-Review 95-019
5 . 5 Depth Profile of Damage Structures in Triple-BeamIrradiated Auslenitic Stainless Steel
Shozo HAMADA, Yichuan ZHANG*, Yukio MIWA andDaiju YAMAKI
Department of Materials Science and Engineering, JAERI and* Southwestern Institute of Physics, P.R. China
1. Introduction
Austcnitic stainless steels as structural materialsfor a proposed fusion reactor as ITER (InternatinalThermonuclear Experiment Reactor) have currentlybeen evaluated. The studies of the irradiation damagein materials exposed under fusion-environmentradiation is an important aspect of this evaluation. Itis difficult to evaluate irradiation damage that willoccur in a fusion environment as no prototypereactors currently exist. Therefore, in order to simulatea fusion environment and study microstructuralchanges under it, "triple-beam " ion irradiationfacilines have been developed [1,2] and irradiationexperiments have been carried [3,4].
In ion-beam irradiations,, the damaged region doesnot uniformly distribute in the material, but usuallyconcentrates at some depth from the incident surface.The defect structures vary significantly with distancefrom the incident surface. In order to carry outdetailed analyses of the defect structures of thedamaged region, back-thinning technique is utilizedfor preparation of TEM specimens. Controlledsectioning of the damaged region is necessary prior toback-thinning. The sectioning depth is oftentheoretically determined using calculation codes. Thismay lead to wrong results in case of ion-irradiation atelevated temperature.
The objective of this study is to show
experimentally the depth distribution of the defectstructures of an austenitic stainless steel irradiatedwith triple-beam at elevated temperature to carry outback-thinning for precise observation of it.
2. ExperimentalThe material used in this study is a titanium-
modified austenitic stainless steel (JPCA). The mainchemical composition is Fc-16Ni-14Cr-0.25Ti-2.5Mo\vt%. Disks of 3 mm in diameter with 0.25 mm in
thickness of this material were solution-annealed for 1hour at 1323K. The irradiation was carried outwithout a degrader using the triple beam irradiationfacility in TIARA cf JAERI. Samples weresimultaneously irradiated with 12 MeV nickel and 1MeV helium and 350 keV proton ions at thetemperature range of 573 - 673 K. The energies ofhelium and proton ions were selected so as to beinjected at same depth. The damage level and injectedconcentration of helium and hydrogen ions at thedepth of about 1.62 fim are 57 dpa, 19000 and 18000appm, respectively
Following to irradiation, the specimen wasprepared so as to carry out a cross sectional viewnormal to the incident surface with a TEM. Nickelwas electroplated on both sides of an irradiated sampleto a thickness greater than 3 mm. The electroplatedsample was sliced into 0.2 mm thick sheet using alow speed diamond saw, and cut into 3 mm disc. Oneside of the nickel-plated disc was mechanicallypolished and chemical-etched by an aqua-rigia saturatedwith CuCl [5]. Observation of the chemical-etchedsurface was carried out through an optical microscope.Then it was electropolished to perforation. Detail ofthe specimen preparation is described to elsewhere[6].The microstructures in a cross-sectionaled samplewere observed with a 2000-FX TEM operated at 200kV.
The theoretical depth profiles of damage producedby nickel ions and the concentration of stopped ionsof both helium and proton were calculated using theTRIM computer code 85 [7].
3. Results and discussionAn optical micrograph of the chemical-etched,
cross sectional surface of JPCA simultaneouslyirradiated with triple beam at 573-673 K is shown infig. 1. The incident ions traveled from right to left in
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JAERI-Review 95-019
incident kgJfo&ftsurface ! " ,.„ ,'/
Fig. 1 Optical micrograph of two lines parallel to theincident surface appeared after chemical etching in thecross sectional view of triple-beam irradiated PCA.
Fig. 2. Two damage bands parallel to the incidentsurface, which consist of dislocation structures withhigh number density.
the micro-graph. Two lines parallel to the incidentsurface appeared in the irradiated sample. The distanceof each line from the incident surface is about 1.34and 2.3 Aim, respectively. In these values, theformer agrees to the projected ranges of both heliumand proton ions, the latter does to that of nickel ions.The line parallel to the incident, surface that appearsby chemical-etching corresponds to the damage region. It indicates that two lines observed may predictexistence of two damage regions in the depthdirection. A typical depth profile of damagestructures by TEM observation is shown in fig. 2. Across sectional view gives not uniform distribution ofmicrostructures, but two bands parallel to the incidentsurface. These bands consist of dislocation structuresas loops and networks of high number density andlocate in the range of the depth of 0.4 to 1.3 £tm and1.8 to 2.4 Aim from the incident surface. Thenumber density of dislocation in each band, which isnot measured yet, seems to increase as the depthincreases. It seems, that is, to become maximum atthe deeper edge (the right edge of each band in fig. 2).The depth of deeper edge of
each band is about 1.3 and 2.4 Aim, respectively.Each depth agrees to the distance from the incidentsurface to each etched-line as shown in fig. 1. Theregion between two bands looks like white image,because of drastically lower number density ofdislocations than in two bands. This does not depend
on the diffraction condition, but substantiallyindicates lower density of dislocations in this region.Actually, two- beam condition of this region indicatesthat the number density of dislocations in the regionbetween two bands is very low even though there aredislocations. Observation, further, with highmagnification of this region shows that small cavitiesof high number density uniformly distribute in thematrix as given in fig. 3. Small cavities with highnumber density are found in the depth range of 1.25 to1.73 Mm from the incident surface and no cavitieselsewhere. The depth distribution of cavities observedagrees to that of stopped helium and hydrogen atomsby calculation. The average diameter and numberdensity of cavities are 1.37 nm and 1.5 x 1024m-3.respectively-
Farrell et al. [3,4] have observed themicrostructures of high purity austenitic alloyirradiated with triple beams (4 MeV Ni, 0.2 - 0.4MeV (He and D)) at 898 K. They employed onlysectioning and back-thinning technique for TEMspecimen preparation and summarized from theirexperimental results that in the region where threebeams of heavy, deuterium and helium weresimultaneously irradiated, dislocation structures andsmall cavities of high number density. In the presentwork, small cavities of high number density areobserved but the number density of dislocations ismuch lower than that of other studies [3,4] as shown
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JAERI-Revicw 95-019
Fig. 3 Small cavities with high number densityobserved in the region of white contrast between twodamage bands as shown in fig. 2.
in fig.2. The experimental difference among thesestudies seems to consist in irradiation temperature :One is 923 K, another is 573 - 673 K. Thistemperature difference during irradiation may causedifferent dislocation density. It is predicted that fastermigration of hydrogen atoms at 923 K and lower oneat temperatures below 673 K. The difference ofmobility of hydrogen may make different interactionbetween hydrogen atoms and helium / interstitialatoms, as a result produce lower density of dislocationstructures. In order to reveal this possibility, it isnecessary to show the temperature dependence ofirradiation damage structures under triple beamsirradiation in the future.
4. Conclusions(1) The depth profile of irradiation damage staictures
shows good agreement to that obtained bycalculation.
(2) Simultaneous irradiation of nickel, helium andhydrogen ions at the temperature of 573 - 673 Kmakes the number density of dislocationstructures lower.
[3] Simultaneous irradiation of helium and hydrogenions enhances formation of small cavities.
References[1] M.B. Lewis, N.H. Packan, G.F. Wells, R.A.
Buhl, Nucl. Instr. & Methods, 167, 233 (1979).[2] S. Hamada, Y. Miwa, Y.Katano, T. Nakazawa,
K. Noda, JAERI-Review 94-005, TIARAANNUAL REPORT, 1993, 105 (vol. 3).
[3] K. Farrell, M.B. Lewis, N.H. Packan, ScriptaMet. 12, 1121 (I97S).
[4] N.H. Packan, K. Farrell, J. Nucl. Mater. 85 &86,677 (1979).
[5] K. Shiraishi and K. Fukai, J. Nucl. Mater, 117,134 (1983).
[6] S. Hamada, M. Tanaka and K. Shiraishi, J.Nucl. Mater, 114,338(1983).
[7] I. Manning, G.P. Mueller, Comput. Phys.Commun. 7, 85 (1974).
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JAERI-Review 95-019
5 . 6 Microstructural evaluation of single crystalline A12O3
irradiated with triple ion beams
Yoshio KATANO, Tetsuya NAKAZAWA, Dayu YAMAKI,Takeo ARUGA and Kenji NODADepartment of Martials Science and Engineering, JAERI
1. IntroductionAlumina with excellent electrical and
optical properties has been proposed forone of electrical insulators and diagnosticmaterials in fusion reactors[l]. In thefusion reactor environment, ceramic in-sulators will be subjected to severe radia-tion damage arising from high displace-ment damage and large amount of trans-mutants such as H and He due to highenergy neutrons. The amount of H and Heintroduced in A12O3 by nuclear transmuta-tion reactions are estimated to be severaltimes as large as that in austeniticstainless steels[2]. Several studies on theeffects of H and He on damage structuraldevelopment have been performed for.A12O3[3,4]. However, the syncrgistic effectsof H and He on radiation damage be-havior has not been fully understood yet.
In the present study, the damagestructure in A12O3 after triple (H+, He+ andO2+-ions), dual (Hc+ and O+-ions) andH+-ion irradiation is studied by cross-section transmission electron microscope(TEM) investigations to obtain funda-mental knowledge on defect clusterformation in fusion reactor conditions.
2. Experimental procedureThe specimens used in this study were
disks (0.2 or 0.5mm in thickness, 10mmin diameter) of pure (nominal purity;99.9%) single crystal alumina (a-Al2O3)
with surface perpendicular to (0001) plane.Ion-irradiation was carried out in the
"triple-beam irradiation apparatus"installed in TIARA at Takasaki estab-lishment of JAERI[5], Specimens wereirradiated with triple beams(H+, He+ andO2+ ions), dual beams(He+ and O+ ions)and single H+-ion beam, respectively, at650°C (0.4Tm) up to a fluence of 2 xlO^ion/m2. Doses in displacement peratom (dpa) are calculated by TRIM89code[6] and evaluated as O.ldpa, 0.8dpaand 3dpa at the damage peak for H+, He+
and O+ ions irradiations, respectively.
After irradiation, disks were cross-sectioned and ion milled(6 keV Ar-ions)at liquid N2 temperature to achivc TEMspecimes. TEM observation was performedusing the JEM-2000FX operating at200kV.
3. Results and discussionCross-sectional electron micrographs of
damage structure are shown in Fig.l(a)and l(b) for single crystal A12O3 irra-diated with H+, He+ and O+ or O2+ ions at650°C. In A12O3 irradiated with ions withdifferent projected ranges, in sequence of0.3MeV H+, 0.6MeV He+ and 0.8MeV O+
ions (Fig.l(a)), defects cluster in damageregion due to H+ ions, He+ ions and O+
ions were observed around depths of 1.8,1.3 and 0.8jim from the surface, respec-tively. The damage structures were
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JAERI-Review 95-019
strongly affected by kind of irradiation.Defects clusters of about 30nm in averagediameter were introduced with the numberdensity less than 1 x 1021/m3 by H+-ionirradiation, and the size of the clusterswas larger than those by He+ and O+ ions.The depths of observed damage structuresare larger by about 20% than those ofdisplacement damage calculated byTRIM89, for respective ion species.
Fig. l(b) shows damage structure ofA12O3 irradiated with the triple-beams i.e.,simultaneous irradiation of 0.25MeV H+,0.6MeV He+ and 2.4MeV O2+ ions, whereaverage ranges of these ions are almostsame to be 1.5(xm. A very high density(higher than 5 x 1022/m3) of disloca-tion loops about 50nm in average diameterwere observed in the damage region.These loops are formed on both basal(0001) and prismatic {1010} planes, withBurgers vectors of 1/3(0001) and 1/3(1010), respectively. These characters ofdislocation loops were the same as those
y.
Fig.l. Depth-dependent microstructure ofA12O3 irradiated with (a) single beams and(b) triple beams.
(b)
(c)
Fig.2. Cavities formation of A12O3 irra-diated with (a) triple beams, (b) dualbeams and (c) H+ ions.
observed [4,7] in A12O3 samples irradiatedwith He ions.
Figs.2 (a),(b) and (c) shows damagestructure of A12O3 irradiated with triplebeams (H+, He+ and O2+ ions) and dualbeams (He+ and O+ ions) and H+-ionbeam, respectively. Cavities with averagediameter of 13nm were observed in thedamaged region of A12O3 irradiated withthe triple beams up to 3dpa at peak. Thisaverage diameter is 1.5 to 4 times largerthan those of cavities in the sampleirradiated with the H+ ions to O.ldpa andthe dual beams to 2.8dpa at peak. InA12O3 irradiated with the dual beams,cavities were aligned along c-axis. Thesealigned cavity formation in A12O3 v/as alsoobserved in the sample irradiated with He+
ions above room temperature in theprevious study [8]. In the study the Heatoms were found to occupy only inter-stitial sites along the c-axis. On the otherhand, in A12O3 irradiated with H+ ions,
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JAERI-Review 95-019
many cavities were formed inhomo-geneously in the vicinity of dislocationloops.
Cavity densities are shown as afunction of depth in A12O3 irradiated withthe triple beams, the dual beams and H+
ions in Fig.3 (a), (b) and (c), respec-tively. The cavities due to irradiation withthe triple beams, the dual beams and theH+ ions are distributed from 1.2 to1.75|xm, 0.55 to 1.35um and 1.35 to 2.05\im in depth, respectively. The extent ofcavity-introduced region of depths for thetriple-beam irradiation is smaller than thatfor the dual-beam irradiation, and issimilar to that for HMon irradiation. Theinhomogeneous formation of the cavitieswere observed for the triple-beam irr-adiation and the H+-ion irradiation incontrast with the aligned distribution ofcavities for the dual-beam irradiation.These suggest that implanted H atomsplay an important role in evolution ofcavities for the triple-beam irradiation.
Authors wish to thank Mrs. S.Hamada and Y. Miwa and the staffs inthe accelerator facility of JAERI for theirinvaluable help to the irradiation ex-periments.
References[1] F.W. Clinard Jr., J. Nucl. Mater. 85
& 86 (1979) 393.[2] G.R. Hopkins and RJ. Price, Nucl.
Engrg. Des./Fusion 2 (1985) 111.[3] S.J. Zinkle, J. Nucl. Mater.
219 (1995) 113.[4] Y. Katano, H. Ohno, and H. Katsuta,
J. Nucl. Mater. 155-157 (1988) 366.[5] S. Hamada, Y. Miwa, Y. Katano, T.
Nakazawa and K. Noda, JAERI-
2.0
1.0
0.0
H: 0.25 MeV[r Hc:0.6MeV
O: 2.4MeVD=13nm
0.8 1.2
2.0
:S 1.01-
S 0.0 E
Depth (^ i
Fig.3. Comparision of the cavity densitydepth profiles in A12O3 irradiated at 650°Cwith (a) triple beams, (b) dual beams and(c) H+ ion beams. D is average diameterof cavity.
Review 94-005, TIARA AnnualReport, 1993 (Vol.3) 105.
[6] J.F. Ziegler, J.P. Bietsak and U.L.Littmark, "The Stopping and Rangeof Ions in Solids" (Pergamon, NewYork, 1985)
[7] S.J. Zinkle, "Effects of Radiation onMaterial", ASTM-STP 1125, eds.R.E.Stoller et al. (American Societyfor Testing and Materials,Philadelphia, 1992) p.749.
[8] G.P. Pells, J. Nucl. Mater. 155-157 (1988) 67.
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JAERI-Rcview 95-019
5 . 7 Microstructural Studies of Ion-Irradiated Ceramic Materials
H. Saka, K. Kuroda, N. Noda*, Y. Katano* and T. Nakazawa*School of Engineering, Nagoya University and*Tokai Establishment, JAERI
IntroductionMany kinds of ceramic materials are
considered to be used in fusion reactors.Improvement in the resistance to irradiationdegradation of ceramic materials is desiredfor development of fusion reactors.Characteristic feature of the irradiationdamage under the irradiation conditions infusion reactor is to accompany generation ofhelium gas due to nuclear reactions betweencomponent atoms and fusion neutrons. Thehelium gas has a large influence on thedimensional instability characteristics such asswelling through the formation of bubbles aswell as displacement damage due to energeticneutrons. Therefore investigations of theeffects of displacement per atom (dpa) andgenerated gas on the irradiation damage arerequired to evaluate the irradiation resistanceperformance of the ceramic materials underfusion reactor conditions. In this study, thedamage structure of A!N irradiated withoxygen ions, helium ions and protons wereinvestigated to get fundamental informationfor the improvement in the resistance toirradiarion degradation.
ExperimentalThe specimens used were sintered
A1N. The specimens were irradiated at873K with triple ion beams. The irradiationof oxygen ions with an energy of 2.4MeV,helium ions with 0.45MeV and protons with0.25MeV was simultaneously undertaken.The fluence of each ion was about 2 x 10 2 °ions/m 2 .
The irradiated specimens weresectioned perpendicularly to the surface witha diamond saw and polished mechanicallydown to the thickness of about 0.05mm.The slice mounted on a single hole grid was
further thinned by a focused ion beam (FIB)system as shown in Figure 1. Two trencheswere milled away in such a way that a thinwall is left behind between the two trenches,the wall being thin enough to beelectron-transparent when tilted by 90degrees.
The specimens thus prepared wereexamined in either a JEOL JEM-200CX or aHitachi H-800 electron microscopes ataccelerating voltage of 200kV.
Results and discussionIt takes only 5 -6 hours to fabricate
the cross-sectional TEM specimens from the0.05 mm thick slice of A1N. The recess withan area 5x5 micronmeter squares wasfabricated to electron transparency. Thisarea is wide enough for the whole depth ofthe irradiated region to be observed. TheFIB fabrication is thought to be a usefultechnique to prepare the cross-sectionalTEM specimen of irradiated ceramics.
Figure 2 shows a typical example ofnear surface microstructures of the irradiatedspecimens. A band of strain contrasts isobserved in the region of about 2micronmeter away from the surface. Theshape of the damage region reflects thesurface morphology. The dpa depth profilescalculated using the EDEP-1 code indicatedthe depths of the maximum dpa were about1.5 micronmeter for the three irradiated ions.This is in fairly good agreement with thedamage distribution observed in Fig.l. Ahigher magnification micrograph of thedamaged region is shown in Figure 3. Highdensity of defects is clearly observed. Thesedefects must be induced by the triple ionbeam irradiation rather than the Ga ionirradiation during the FIB fabrication.
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FIB ETCHING
TEMOBSERVATION
Figure 1 Schematic diagram of cross- sectional TEM specimenfabricated by FIB technique.
Figure 2 Cross-sectional TEM micrograph of AIN irradiated with oxygen ions,helium ions and protons.
Figure 3 Dark field micrograph of region A marked in Figure 2.
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JAERI-Review 95-019
5 . 8 Cascade Damage Formation by High Energy Self-ion Irradiation
Naoto Sekimuraf, Jun Saeki'1, Naoki Ohtakei, Yasuyuki Shiraoi,Seiji Okadai, Yurugi KanzakM, Shiori Ishino2 and Ryuichi Tanakas1 Department of Quantum Engineering and Systems Science,
University of Tokyo2 Department of Nuclear Engineering, Tokai University3 Takasaki Establishment, Japan Atomic Energy Research Institute
1. IntroductionPrimary knock-on atom (PKA) energy
spectrum extends up to several hundreds of keVin fusion reactor materials irradiated with 14MeV neutrons. When we are going to evaluateirradiation behavior in fusion materials using anexpected d-Li type intense neutrons source,fundamental knowledge on effects of highenergy PKA on formation of cascade damageand microstructural evolution is required. Inthis study, 21 MeV and 170 MeV self-ions wereirradiated to thin foils of gold to estimate effectsof very high energy PKA on formation of defectclusters by cascade damage and their interactionscomparing the obtained data with those fromfusion and fission neutron and lower energy ionirradiations.
2. ExperimentalThin foils of 99.99% pure gold were
prepared by electro-polishing after annealing in ahigh vacuum (10-7 torr) for one hour at 973K.These specimens were irradiated with 21 MeV or170 MeV self-ions at room temperature usingtandem Accelerators in JAERI. Ion fluence isranging from 5x10*3 to 1x1015 ions/m2. In thecase of irradiation with 170 MeV self-ions ofwhich range exist at 6.3 mm from the ionincident surface, plates of gold, 1.1, 3.0, 4.3,
6.3 and 7.2 (im in thickness, were placed infront of the specimens to change PKA energyspectrum within the specimens of about 50 nmin thickness.
Irradiation experiments using a 400 keVaccelerator in the University of Tokyo were alsoperformed to compare the cascade damage
structure produced by the single energy cascadedamage.
Post-irradiation observation wasperformed for all the specimens using a JEM-2000FX transmission electron microscopeoperated at 200kV.
3. Results and DiscussionFigures 1 and 2 show dose dependence of
defect cluster density in thin foils of goldirradiated with 21 MeV self-ions and with 170MeV self-ions, respectively.
10 1015
Ion Fluence (ions/m2)
Figure 1. Dose dependence of vacancy clusterdensity in thin foil of gold irradiated with 21MeV self-ions.
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JAERI-Rcview 95-019
At higher dose, defect clusters showsuper-linear dose dependence. Similar dosedependence of density of defect clusters wasobserved in 14 MeV [1] and fission neutronirradiated specimens [2]. These are consideredto come from the conversion of invisible clustersto visible clusters by cascade interactions.Especially when the thickness of the gold plate is6.3 urn which corresponds to the damage peak odepth of the 170 MeV gold ions in gold, the ><super-linear dose dependence starts at lower ^dose because of the higher energy part of PKA. ~
,23
CO
CDQ 10
10 1015
Ion Fluence (ions/m^)
Figure 2. Dose dependence of vacancy clusterdensity in thin foil of gold irradiated with 170MeV self-ions with 3 different plates of gold infront of the specimens.
The minimum interaction distance ofcascade is found to be strongly dependent on thePKA spectrums [3]. By comparing dosedependence of defect clusters in gold irradiatedwith 21 MeV self-ions, fission neutrons and 14MeV neurons, the minimum PKA energy tocause the conversion of invisible defect clustersto visible clusters has been estimated to be 165keV, assuming that cascade zone size increaseswith damage energy form a PKA.
co
E
cCD
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
Defect Cluster Size ( nm)Figure 3. Size distributions of vacancy clustersin thin foils of gold irradiated with 21 MeV self-ions at room temperature.
Figure 3 shows size distributions of defectclusters in thin foils of gold irradiated with 21MeV self-ions. At higher dose, smaller clusterstend to be formed by the interactions ofcascades.
Figure 4 shows dose dependence ofaverage size of defect clusters in thin foils ofgold irradiated with 170 MeV self-ions. In thecase of 21 MeV self-ion irradiation, averagecluster size tends to decrease at higher dose, aswere often observed in fission neutronirradiation experiments [2]. However, averagecluster size does not decrease in 170 MeV self-ion irradiated specimens, average size of defectclusters tends to increase with irradiation dose.In this case, the fraction of high energy PKA inthin foils of gold is large. High energy PKAcan form new larger defect clusters bycombining multiple invisible defect clusters.
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JAERI-Review 95-019
Ion Fluence (ions/m2)
Figure 4. Dose dependence of average size ofvacancy clusters in thin foil of gold irradiatedwith 170 MeV self-ions with 3 different plates ofgold in front of the specimens.
4. References[1] M. Kiritani, T. Yoshiie, S. Kojima and Y.Satoh, Radiation Effects and Defects in Solids113,75(1990).[2] N. Sekimura, to be presented in ICFRM-7,to be published in Journal of Nuclear Materials.[3] N. Sekimura, Y. Kanzaki, S. Okada, T.Masuda and S. Ishino, Journal of NuclearMaterials 212-215,160 (1994).
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JAERl-Review 95-019
5 . 9 Surface Nitridation by Ion Beam Irradiationand Plasma ProcessingMasanobu Nunogaki, Toichi Okada,Hidefumi Takeshital, Yasushi Aokil, ShunyaYamamotol, Hiroshi NaramotoISIR, Osaka UniversityiTakasaki Establishment, JAERI
1. Introduction
The multiplex surface processinghas been carried out for nitridationof pure iron. The new process wascomposed of a precedingirradiation with an ion beam or arelativistic electron beam and thesubsequent nitridation as the mainprocessing. An irradiation acted todistribute impurities or defects in asample surface, and resultantlydecreassed the activation energyfor nitridation. Especially, in thecase of ion implantation, die phasesof nitrogen compound or ironand its thickness varied sensitivelydepending on the kind of ionspecies and a beam fluence.
2. Experimental results
By applying a sequence of newprocess for nitridation of pureiron, hardness and thicknessof nitrogen compound layer werecontrollably improved. Thevariations of hardness vs. thethickness of nitrided layer weredrawn in Fig.l. Each plot ofhardness represented the ratio ofthe modified hardness to one ofraw iron. As shown in the figure,ha rdnes s and thickknessvaried sensitively dependingupon ion species and ion fluence .The curves (a) and (a1) show thetyp ica l hardness changesagainst the depth of compoundlayer measured from the surfacenitrided for 1 and 2 hours,
respectively, without anyirradiation. The curves (b) and(c) show the hardness chauges ofthe samples nitrided for 1 houreach after 2 5 keV-Ni-ionirradiation up to a fluence of 1 x1016 and 7 x 1016 ions/cm2,respectively.
The curve (d) shows anotherexample of increasing thicknessand hardness of nitrided layerirradiated with MeV-order electronbeam. The thickness reached60 At m only for 2 hrs nitridation.The peculiarity was of thehardness, that is, the maximumhardness at the depth of about15/xm was about 7 times largerthan one of raw iron and about 1.5times larger than one of the layernitrided with the Ni-ionirradiation.
By analyzing the components ofthe sample nitrided with andwithout the electron beamirradiation with XPS , theabundance ratio of nitrogencontained in the nitrogencompound layer formed after theelectron beam irradiation was madeclear to be rather decreased,
however, the depth of nitrogendistribution was broadened.
To distinguish the role of Ni-ionbeam irradiation, N2 - and Ar-ionwere pre-irradiated . The resultswere shown in the curves ( e )and ( f ) , respectively.
Facilities and InstrumentsTandem Accelerator(Takasaki Estab.)
Research FieldSurface Modification
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JAERI-Review 95-019
The effects of N2 - ionirradiation on increasing hardnessand thickness were detected at a
higher ion fluence over 5x10 ^ions/cm * The maximum hardnesswas almost at the same level with Ni-ion irradiation, however, thethickness of Fe 4 N, 7'-phaselayer was rather thin. It was notexplained reasonably yet.
The curve (f) indicated that Ar-ion irradiation was almostineffective on increasing hardnessand thickness of modified layer .
From the phase diagram of Fe-Ntwo elements and the abundanceratio of components in the nitridedlayer , it was concluded that s -phase layer was formed merely atthe outermost surface. Thedecrease of the relative hardness atthe surface as seen inthe curves ( a'), ( c ) and ( e )indicated the formation ofF e 2 - 3 N > £ " Phaselayer at the outermost surface.These variations instructed that theion species and fluence were ableto control the thickness of sphase layer, whose hardness was
nC
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6.0
7.0
6.0
5.0
4.0
3.0
2.0
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0.0
- A
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ft
V\-* \ '
V \
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I
0.0 20.0 40.0 BO.O
Thickness
B0.O 100.0
less than one of y' - phaselayer. The mechanism ofthese thickness and phase changeswas not u n d e r s t a n d yetexperimentally. It is noteworthyfrom the industrial point of viewthat the selective formation ofthick r-layer at the surface ofiron is useful to increase the wear-resistance of tools and to performthe accurate surface processing ofmachinery.
From these results, it wassummarized that the Ni-ionirradiation had a role to decreasethe activation energy for theabsorption , and that the electronbeam irradiation mainly acted toassist the diffusion of nitrogenatoms in the surface layer due tocreation of the irradiation-induced defects.
3. Conclusion
The multiplex surface processingcomposed with the preparativeirradiation of 25keV-Ni-ion beamor 20MeV-electron beam as thefirst process and the subsequentnitridation as the main one wasuseful to form the nitrogencompound layer in the surface ofpure iron. Further investigationwill be continued to analyze themechanism of enhanced-nitrogenabsorption by the irradiation.
Fig. 1 Typical characteristic curvesobtained by applying the multiplexsurface processing for nitridationof pure iron.. Irradiation of20MeV-electron beam or 25keV-Ni-ion beam was eminently effectiveon increasing the thickness ofnitrogen compound layer formedwith the subsequent nitridationtreatment.
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JAERI-Review 95-019
5 . 1 0 Defect Formation in LiF Irradiated with 175 MeV 40Ar ions.
Yasushi Aoki, Shunya Yamamoto, Hidefumi Takcshita, Hiroshi Naramoto,f Akihiko Osa, fNoriko Shigeta, tMituo Koizumi, tHiromiisu Matsuoka,and fToshiaki SekineJAERI-Takasaki, Department of Materials Development and Department ofRadioisotopes
Ion irradiation introduces variouskinds of defects in materials and in manycases the physical properties, such aselectrical and optical properties, ofirradiated materials are derived from thenatures of the defects. Thus, in order tocontrol the physical properties by means ofion irradiation, precise and detailedinvestigation is necessary about the kind ofion-induced defects and the efficiency of itsformation. On the other hand, if physicalproperty can be measured along the depth inirradiated material, for example observationof the optical absorption due to the defects,the energy loss process of high energy ionsin material, mainly based on the electronicstopping, will appear from the view point ofdefect formation. Furthermore, theoverlapping effect of ion tracks can beestimated from the delicate analysis of thechange of absorption with the irradiationdose in such observation.
Ion irradiated alkali halides havebeen investigated in terms of the depthprofiles of defects by microscope-photometric methods, micro hardness etc.,for example LiFO-3), KCK4) and NaF(5).The depth profiles of the simple anioniccolor centers have been found to give a goodcorrespondence to the electronic energy lossprofiles for LiFO'3). We measured theoptical absorption spectra for LiF singlecrystals irradiated with 175 MeV 40Ar8+,and showed the formation of anionic defects(F-center) and its aggregation states (F2-center, F3-center)(6X In this paper, we willshow the dose dependence of the absorptionspectra and the annealing behavior.
Single crystal LiF block (HarshawChemical Company) was prehardened byirradiation of y-ray and cut into platelets
whose size were about 7 mm x 7 mm x 1mm. Thermal annealing was done at 600°Cin air for 400 hr's in order to eliminate thepreexisting defects before ion irradiation.Ion irradiation with 175 MeV 40Ar8+
w a s
performed at the port LA-1 of AVFcyclotron (TIARA, JAERI-Takasaki) Thesamples are fixed on Al plates and coveredthe half with Al foil to get unirradiated parton the samples. The Al plates with sampleswere set on the water-cooled targetchambers and samples were irradiated undervacuum around 1 x 10"5 Pa. The currentand the cross-sectional area of the ion beamwere 2 nA and 1 cm2, respectively. Afterirradiation, samples were reserved in a dark,cool and low-humid place for more than 2weeks to wait for decrease in radioactivity.
Optical absorption of irradiatedsamples were made with a microscopephotometer (MPM800, Zeiss) at roomtemperature. In the observation ofannealing behavior, samples were annealedrepeatedly changing the annealingtemperature from 120°C to 400°C. Theannealing period at the constant temperaturewas set 30 minutes.
Fig. 1 shows the optical absorptionspectra of Ar irradiated LiF single crystals inthe wavelength region of 230 to 800 nm forthe irradiation dose of 1.3 x 1011 to 1.3 x1012 ions/cm2. As the irradiation doseincreases, the absorption peaks around250nm (F-center) and 444nm ^-center)grow and I^-centers (Rj, R2 and Rn)absorption appear at the largest dose (1.3 x1012 ions/cm2). They are observed at thewavelengths of 312, 375 and 551 nm,respectively. In addition, at 407 nm a weakabsorption can be observed as a shoulder ofthe F2-center absorption. It may be
- 109 -
JAERI-Review 95-019
absorption by Li-colloid in the irradiatedLiF. It should be noted that 250 nmabsorption is shifted with increase in theintensity. It now cannot be interpretedwhether it shows the change in theelectronic structure of F-center occurs or theexistance of more than one kinds of speciesabsorbing light around 250 nm
ouca
.o<
2.7 x lo" iuno'cm2
1.3 x Id" ium'cm2
400 600wavelength, nm
Fig. 1 The absorption spectra of LiF single crystalsirradiated with 175 MeV 40Ar ions.
Fig. 2 shows the depth resolved ab-sorption spectra measured for Ar irradiatedsample with the largest dose (1.3 x 1012
ions/cm2). The estimated projected rangeof 175 MeV 40Ar in LiF is about 36 urn andthe depth resolution of the measurement
1.5
D
a 1
O
l o . s
0
• A~f\: [ ji
: \
*—.
. . i . i • i . . . i
A.y '^ i i 5(1111/ / V\ 15(im
/ / \ \ 35ji.ni// \ \ 45(im// \ \ 55(im J
, . 1 , , . 1 . , , 1 .400 601)
wavelength, nm800
Fig. 2 The depth resolved absorption spectra of 175MeV 40Ar irradiated LiF single crystal. Theirradiation dose is 1.3 x 1012 ions/cm2.
was 4 jam. During the ion range, intenseabsorption is shown by F-center, F2-center,F3-center and Li colloid. It means the
efficient defect production by electronicenergy deposition of Ar ions. It seems theexistence of another absorption around 480
nm, but now cannot be identified. Again,the higher energy peak lies around 270 nmwithin the ion range and the peak liesaround 250 nm around the ion range. Thedefect formation efficiency is not so higharound the ion range, compared with theshallower region and even at the depth (45(am) beyond the ion range, still the anionicvacancy are formed. It probably shows thecontribution of secondary radiation to thedefect formation.
Fig. 3 shows the annealing behaviorof optical absorption for the Ar irradiatedLiF single crystal to the dose of 1.3 x 1012
uca
x>O 1
400 600wavelength, nm
800
Fig. 3 The change of absorption spectrum of 175MeV 40Ar irradiated LiF single crystal by thermalannealing treatmet in air. The irradiation dose is 1.3 x1012 ions/cm2.
ions/cm2. The absorption observed atshorter wavelength region (250-260nm)decreases with blue shift, showing areversible process between defect formationand thermal annealing. The absorptionfeatures at longer wavelengths by theaggregation states of anionic vacancies (F2
and F3) also decreases with the annealingtemperature. In the course of the annealing,a clear peak around 410 nm appears by200°C annealing and disappears after 300°Cannealing. After 300°C annealing, themain features are observed around 250 nmand 440 nm. But after 400°C annealing
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JAERI-Review 95-019
there is no appreciable absorption in themeasured spectrum.
The processes of defect formationand thermal annealing are not alwaysreversible. In order to understand theenergy loss process of high energy heavy ionin materials by means of observation of thedepth profile of created defects in LiF, it isnecessary to clarify the response to radiationin more detail.
References(1) A. Kikuchi, H. Naramoto, K. Kozawa and Y.Kazumata, Nucl. Instr. and Meth. B39 (1989)724.(2) L.L. Regel, V.R.Regel, S.E. Boriskin, G.G.Knab, A.A.Ursovskaya, L.I. Alekseeva and V.V.Klechkovskaya, Phys. Stat. Sol. 73 (1982) 255.(3) A. Perez, J.Davenas and C.H.S. Dupuy,Nucl. Instr. and Meth. 132 (1976) 219.(4) M.Luntz, P.E. Thompson, R.B. Murray andD.J. Whittle, Radiat. Eff. 31 (1977) 89.(5) K. Kubo, J. Phys. Soc. Jpn. 35 (1973) 125.(6) Y.Aoki, S.Yamamoto, H.Takeshita, H.Naramoto, A. Osa, N. Shigeta, M. Koizumi,H.Matsuoka and T.Sekine, JAERI TIARA Ann.Rep. 1993 (1994) 101.
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JAERl-Rcvicw 95-019
5 . 1 1 Ti ion implantation into TiO2 rutile single crystals
Yasushi Aoki, Hidefumi Takeshita, Shunya Yamamoto, PeterGoppelt and Hiroshi Naramoto.JAERI-Takasaki Department of Materials Development
Ion implantation is a methodwhich can introduce any impurityelement into any matrix to modify thephysical and chemical properties of thesurfaces. In this technique, the intro-duction of impurities is substantially innon-equilibrium manner and bring aboutformation of defects and non-equilib-rium states in the near surface region ofmaterials. Although any combination ofimpurity and material can be selectedand the depth of the modified layer canbe controlled, defect formation and itsannealing behaviors are important forthe resultant microstructures andproperties.
Here we implanted TiC>2 rutilesingle crystal with Ti ions. TiC>2 has a 3eV band gap and transparent in thevisible region. Titanium oxides showsemiconducting characteristics and TiO2
has been used a catalyst to decomposeH2O, oil, CO2 gas etc. In general,transition metals can take some kinds ofcharge states in their oxides and eachoxide has individual properties. In thecase of titanium, only titanium dioxidesis regarded as an insulator. Otheroxides with precise stoichiometry andnon-stoichiometric oxides show semi-conducting and metallic properties.Parker and KellyO found anddemonstrated that TiC>2 rutile single andpoly crystals can be transformed toT12O3 polycrystals through sputteringprocess with 30 keV Kr ions.Nakamura et al.(2) implanted p-typedopant In into TiC>2 an(* the recovery ofthe implantation defects of TiO2 crystalsand substitutionality of the impuritywere investigated along the isochronalannealing, using RBS/ channelingmethod. They suggested two kinds ofrecovery processes and escape of the
impurity from the surface at asufficiently high temperature. In thepresent report, we focus on the defectformation and its recovery process in thecase of self ion (Ti) implantation intoTiO2 single crystals by means ofRBS/channeling method.
Single crystal rutile TiO2 (001)(Nakazumi crystal laboratory) was usedin this study. The surfaces werepolished with mirror like finish andannealed in air for 4 hours at thetemperature of 600°C. Ion implantationwas done with 200 keV Ti ions, using400 kV ion implantor of TIARA inJAERI-Takasaki. The implantationdoses were 1.2 x 1016 ions/cm2 for 130Kimplantation and 7.7 x 1015 ions/cm2 forroom temperature implantation. Afterimplantation, the samples were annealedin air and under vacuum ( l x l 0~6 Torr)isochronally from 300°C to 1000°C withthe annealing time of 1 hour at eachstep. At each annealing step thedisorder of the crystal samples wasanalyzed by RBS/ channeling methodwith 2 MeV He+ ion from 3 MV single-ended accelerator of TIARA in JAERI-Takasaki. The incidence of theanalyzing beam was set to the normal tothe (001) surface under channelingcondition and the scattered ions wasdetected at 165° with respect to theincident direction.
Fig. I shows the RBS channelingspectra measured for Ti 130K-implantedTiO2(001) at several annealing steps.At first, amorphized surface layer wasobserved in the as-implanted TiC>2crystal and thermal annealing processmade the damaged layer recoveredgradually with temperature increase.The recovery process can be divided intotwo processes as those found by
- 1 1 2 -
JAERI-Revicw 95-019
Nakamura et al.(2) and by Khubeis andMeyer(3), for In implantation and Hfimplantation, respectively. Fig. 2 showsthe changes in thickness of damaged
, 2000 -
.S 1000 -
•a
;
- / , * / • .<
/I Jr
random •
niinpl •Wfft 500 c^ \ * 500 r -
ti «oo c\W 800 C
V * — "> 0° ' •
1 . i
1200 1400
energy (kcV)1600
Fig. 1 The random and aligned <001> RBS spectra of200 kcV Ti implanted TiO2 single crystal. Thetemperature and the dose of the implantation arc 130 Kand 1.2 x 10'^ ions/cm^, respectively.
layers and in area under the depth profileof damage obtained by RBS analysis inchanneling condition. Those are plottedas a function of annealing temperaturefor annealing in air and under vacuum.
500 1000
Hng temperature ( C)
Fig. 2 The changes in residual disorder and thicknessofdamaged layer of Ti implanted TiC>2
The two samples annealed in air andunder vacuum show a similar behaviorup to 500°C, but there is the second steparound 600-800°C for vacuum anneal-ing, and around 800-1000°C for in-air
annealing and finally both samples arerecovered completely. In the annealingin air of TiO2 implanted 200 keV Tiwith the dose of 7.7 x 1015 ions/cm2 atroom temperature, the damage did notreach to the amorphous level afterimplantation and the damage recoveredcompletely by the annealing up to thetemperature of 500°C.
The damage formed in the lowtemperature implantation has been foundto have two kinds of annealing steps.The one is observed between 300 and500°C. Lightly damaged layer formedby room temperature implantation in thisstudy disappeared almost completely inthis temperature range. The implanta-tion coloration probably due to Ti3+
interstitial4) also disappeared by thisannealing in air. On the other hand,thermal coloration occurred on thennimplanted T1O2 ar^er annealing undervacuum. Then in this stage ofannealing, atoms can move in the TiC>2lattice and even through the surface andit could be regarded as an usualannealing behavior.
The second stage of annealingwas observed 800°C under vacuum and1000°C in air. As seen in Fig. 2, in theannealing in air, the apparent damagewas slightly increased and the thicknesswas kept at the constant value. It couldbe considered that new phase wasformed in this temperature range (500-800°C). The faster recovery undervacuum seems to suggest that thephenomenon is possibly loss of materialfrom the surface rather than recovery torutile. It also supports the expectationof new phase formation because 1000°Cis even lower than the melting point(1840°C) of rutile under ambientcondition.
(1) T.H.l'urkcr and R.Kelly, J.l'hys. Chem. Solids,360975)377-385.(2) S.Nakamura, K.Yagi, T.Osaka and M. Iwaki, Nucl. Instr.and Mctli., 1333(1988) 729-733.(3) I.Khubcis and O.Meyer, Malcr. Chcm. and 1'hys.,38(1994)284-288.(4) M.Gucmiizi, lVliievenard and M.G. Blanchin, Radial,lifl'., 49(1980) 61-64.
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JAERI-Rcview 95-019
5 . 1 2 Metastable Phase Formation by Ion Implantation (III)- High Dose Implantation of Silver into Silicon-
Hidcfumi TAKESHITA, Yasushi AOKI, Syunya YAMAMOTOand Hiroshi NARAMOTO
Takasaki Radiation Chemistry Research Establishment, JAERI
Ion implantation of noble metals such asAu and Ag into Si crystals producessupersaturated amorphous alloy1>2). In thepresent work, we focused our effort on theformation of mctastablc intermediatecompounds. For the Ag-Si system, theoccurrence of two mctastablc phases inrapidly solidified alloys was reported on theAg-rich side of the phase diagram3'. One ofthe problems in the preparation of thosecompounds by ion implantation is whether itis possible to achieve a sufficientconcentration of implanted species in asubstrate, because it is well known that thereis a limit to the maximum concentration ofimplanted species. This is a result ofsputtering, where atoms near the surface canreceive sufficient energy to escape the solid.
Therefore, first of all we carried outhigh-dose implantation experiments to checka relation between irradiation dose andretained amount of the implanted atoms.Samples of silicon disk were irradiated with400kcV Ag+ ion at room temperature in adynamic vacuum better than 10"5Pa. Themaximum beam energy which was availblcfor the 40()kV implantcr was chosen tolocate implanted atoms at a deeper positionin the substrate and to reduce the sputteringyield. The beam current was about KliiA.
Fig.l shows a result of the Rutherfordbackscattcring analysis for typical samplesheavily implanted with Ag. In this figure, adepth scale was added to give a roughestimation of the distribution of implantedAg atoms in the Si substrate. For the lowestdose of 4.2x1016/cm2, the peak of thedistribution of implanted Ag atoms isobserved at a depth of around 1700A, whichis consistent with the calculated projected
range of 1800A for 400keV Ag ionsimplanted into a Si substrate. Thus, in thisdose range sputtering does not have asignificant effect on the ion distribution in thesubstrate. For higher doses of 1017 to10I8/cm2, however, the effect of sputteringbecomes more remarkable. This situation isclearly observed in Fig.l. With increasingdose, the depth profiles of the implanted Agmove to the substrate surface and the peakconcentrations seem to saturate at the levelof about 20-30at.%Ag.
References1) JAERI TIARA Annual Report Vol.2(l993)932) JAERI TIARA Annual Report Vol.3(1994)933) T.B. Massalski, Ed.-in-chief, "Binary Alloys
Phase Diagrams", 2nd. Ed.,ASM InternationalVol.l(1990)92
5000
1500 1600 1700ENERGY (keV)
1800
Fig.l Rutherford backscattcring energy spectrafrom Ag atoms implanted into Si single crystalwith the energy of 400keV, taken with 2.0-MeV4He ions.
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JAERI-Review 95-019
5 . 1 3 Development of High-Functional FullereneThin Films by Ion Implantation
H.Koinuma, M.Yoshimoto, M.Sasaki;;, S.Ohashi, T.Asakawa, H.Koyama'v,S.Gonda, T.Arakane, T.Shiraishi';, H.Takeshita2', S.Yamamoto2', Y.Aoki2),P.Gopperlt-Langer^, H.Naramoto2)
Res. Lab. ofEng. Mater., Tokyo Inst. of Tech.''FacultyofEng., Dept. ofCommun., Tokai Univ.2)Dept. of Mater. Develop., JAERI/Takasaki
INTRODUCTIONIon implantation into fullerene such
as C60 is expected not only to inject carriersby the charge transfer between fullerene andthe implanted ions but also to form newcompounds by the encapsulation ofimplanted ions in the fullerene sphere.Another possibility is chemical reaction ofthe implanted ions with fullerene to formsuch molecules as those obtained by theconventional addition reactions withhydrogen and fluorine in liquid or vaporphase1)>2). In this study, we have implantedvarious ions into Ceo thin films andinvestigated the physical and electricalproperties of implanted films.We also reportour preliminary study on the photoelectrontotal yield spectroscopy (PYS) of fullerenefilms. We have developed this method toobserve the electronic density of states invarious electrofunctional materials with aresolution (<10meV) much higher thanthat achieved by the conventional XPS andUPS.
2.EXPER1MENTALC60 thin films were deposited on
various substrates at temperatures between23°C and 120°C by vacuum evaporation(5xlO6 Torr) of C60 powders (purity>99.5%) from an alumina crucible heatedat 500°C. The substrates used were fusedsilica glass, cleaved NaCl(lOO), and Si(l 11).Intrinsic electrical conductivity of Ceo thin
films was measured in-situ in thetemperature range between 23 °C and 120°C.From the temperature dependenceofconductivity, the activation energy ofconductivity was also determined.Ionimplantation into the films was performedwith Ag, Mn and H ions at the energiesbetween 30 and lOOKeV. The ion dosewas varied from 1013 to 1016 ions/cm2.
Structure and optical properties ofthe films were characterized by Xraydiffractometry (XRD), Raman scatteringspectroscopy, and UV-visible (UV-VS)absorption spectroscopy. The filmcomponent was analyzed by a laserdesorption time-of-flight mass spectrometer(TOF-MS) and a secondary ion massspectrometer (SIMS) using Cs+ ion beam.
The mid-gap density of states of C6ofilms was in situ studied by photoelectronyield sectroscopy (PYS) using the systemwe constructed based on our original design.
3.RESULTS AND DISCUSSIONFig.l shows X-ray diffraction
patterns of an evaporated C6o film. The Ceofilm deposited on a fused silica glass wasamorphous, but highly oriented fec-polycrystal C60 films were grown on cleavedNaCl(lOO) and Si( l l l ) substrates. Fig.2shows Raman scattering spectra of ion-implanted films. C60 molecules wereapparently decomposed and changed into
- 1 1 5 -
JAERl-Review 95-019
10°
to
"c
CO
(D• » - •
£ ...... on Quartz— on NaCI(100)
on Si(111)
c\T. - ^ CM
IN
SJ. i1 I
A., ., l — j ^ ' i ^
COo(0
co"CO
52-
•
10 15 20 25 30 35 4026 (degree)
Fig. 1 X-ray diffraction patterns of anevaporated Ceo films.
200 400 600 1000 1200 M00 1600
Wavcnumbcr (cm1)
Fig.2 Raman scattering of the 100 KeV Agor Mn-implanted films and non-implantedC60 film.
amorphous carbon by the Ag and Mn-implantation
Fig.3 shows the temperaturedependences of in-situ conductivity for theamorphous and polycrystalline C60 filmsdeposited on fused silica glass and cleavedNaCl(100) substrates, respectively. Theamorphous C60 film had a conductivity of10"4~10'5 S/cm at room temperature and aconduction activation energy of 0.50 eV.The polycrystalline film had a conductivitytwo or three orders of magnitude higher
• 1 • 1
" Ceo/NaCI^^2
C6o/Quartz glass
• I '
Ea=O.15(eV)
Ea=0.5(eV) ~
* * Z m -
• i
1 1 0 - 4
•§ 10"5
<Sio-6
10"7
2.4 2.8 3.21000/T(1/K)
Fig. 3 Temperature dependences of in-situconductivity for the amorphous andpolycrystalline Ceo films.
10-7
XI
k 10-9wB
10"
inc0)Q 10"11
10"12
10"13
Total Yield:—NaCI(Tsub.=150°C)
—NaCI (Tsub.=R.T.)••••Sapphire (Tsub.=R.T.)
3.5 4.0 4.5 5.0 5.5 6.0
Photon Energy [eV]
Fig.4 The occupied DOS of the Ceo filmsprepared under various conditions.
and an activation enegy 0.15eV muchsmaller than those of the amorphous C6ofilm, respectively3'. Fig 4 shows theoccupied DOS distributions deduced from
- 1 1 6 -
JAERI-Rcvicw 95-019
PYS for the C^ films prepared under threekinds of conditions. The crystallinity of C6ofilms was increased in the following order: Ceo/sapphire < Ceo/Nad (R.T.) < Ceo/NaCl(150°C). It is noteworthy that the densityof gap states clearly increased withimproving of the film crystallinity. Itindicates that the conduction in C60 films isdominated by the hopping mechanism.
Fig.5 shows TOF-MS spectra oflO'Vcrn2 H-ion implanted film. The intensity
0
4-*
:ens
i
^ »
i i i i i i i
C6o 1 60
1 1 1
m/o a1
I t I i i
720.0loot •
90 -80 -7 0 •60 •50 -4030 •20 •10 •
Ot
72
Vv
1 1
•BB•
I I . . .I I I I i I
J 725
1 1 1
680 700 720 740 760
Mass (ni/z)
Fig.5 TOF-MS spectra of the 1013 H-implanted film , and the inset shows thetheoretically calculated Ceo isotope peakratio.
ratio of the peaks at 721m/z to 720m/z forthe implanted film was higher than thetheoretical intensity ratio for C60 filmscaluculated from the natural abundance of12C (98.89%) and 13C (1.11%) isotopes inC6o as shown in the inset of Fig.4. Thepeaks at 721, 730, 732 and 736m/z areassignable to C6oH, C60H10, C60H12andC6oHi6, respectively. The presence ofC60H molecule attracts our interest from theview point of the possible production ofendohedral H@C6o molecule through theimplantation of H+ ion with a diametersmaller than the inner size of a benzene
ring in the C60 molecule.
4.SUMMARYAmorphous Ceo films had
conductivities three orders of magnitudelower than those of fcc-polycrystalline C60films. Ag-ion implantations increased theconductivity of C60 films andsimultaneously induced the decompositionof C60 molecules into amorphous carbon.In the TOF-MS spectrum of the Ceo filmimplanted with 1013 H-ions/cm2 at 30KeV,we obsorved new peaks corresponding toC60H, C60H10, C60H12, a n d C60H16,
suggesting the possibility of H-encapsulatedfullerene formation by the H+ implantation.
ACKNOWLEDGMENTThe authors thank Prof. O.Odawara
(Tokyo Inst. of Tech.) for his SIMSmeasurements. This work was supported inpart by a Grant-in-Aid for ScientificResearch from the Ministry of Education,Science and Culture of Japan and wasperformed under JAERI/TIARACollaboration Program.
REFERENCES1) R.E.Hauflar et al. : J. Phys. Chem.94(1990)86342) H.Seling et al. : J. Am. Chem. Soc. 113(1991)54753) T.Asakawa et al. : Jpn. J. Appl. Phys.34(1995) 19584) S.Gonda et al. : Mat. Res. Soc. Symp.349(1994)325
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JAERI-Review 95-019
5. 14 Radiation Damages in Synthesized Silica Glassesby High Energy F e Ions Irradiation
I nduced
S . N A S U 1 , S . O O N I S H 1 1 . K . N 1 8 H I W A K 1 1
R . F U J I M O R I 1 , H . N A N T O 1 , R . Y A M A M O T O 1
H . T A K E S I i l T A 2 , Y . A O K I 2 , S . Y A M A M O T O 2
and H . N A R A M O T O 2
'Kanazawa Inst i tute of Technology,I shikawa, 921 J apan
"Japan Atomic Energy Reserch Institute,370-12 Japan
7-1 Ohgigaoka Nonoichi,
Takasaki, Gunma,
1. I ntroductionSilica glasses have been used for
optical transmissive and reflectivematerials, such as envelops of speciallamps, high temperature furnace materi-als for semiconductors, cores and clad-dings of glass fiber waveguides, andgate, field, and passivation layers ofsilicon based metal-oxide-semiconductordevices. In these applications, theresistance to ultraviolet lights, x-rays7-rays, and particle radiations is re-quired. In the light of the above back-ground, F e + 2 ions with 5.5McV were ir-radiated into synthetic silica glassesof SK1300(typel) and SK1310 (typelV) inattempt to bring about radiation damagesat near surfaces of these silica glass-es, and the defects were studied by meansof optical absorption (OA) and photo-luminescence (PL) measurements at roomtemperature (RT) with iterative isochro-nal annealing up to 650 °C.
2. ExperimentalCommercially available synthetic sil-
ica glasses, SK1300 (type III, Oil content:~200wppm) and SKJ310 (type TV. OHcontentrbelow fj wppm) were used as sam-ples. These samples were irradiatedat RT with 5. 5MeV F e YZ ions to theflucncc of 3 X 1 0 1 6 ions/cm2 using theTIARA 3MV tandem accelerator in JAERI,Takasaki. The beam of about 200nA wasscanned on the surfaces of the samplesto get horaogenious fluences. The ir-
radiation fluences were determinedby integration of the charge collectedon the irradiated samples. Temperatureof the sample was not monitored duringirradiation. But, from the experi-mental results mentioned below, it issuggested that the heating of thesamples by ion beam was not serious.
All optical measurements were madeat RT. The OA spectra in the visibleand ultraviolet region (6. 2—1.5eV)were obtained with a Hitachi (J-3300double beam spectroiiholometer. Thecontinuous wave PL and PL excitation(PLE) spectra were obtained with aHitachi F-3010 fluorescence spectro-photoineter. After one opticalmeasurement, the sample was subjectedto isothermal annealing procedure for30 minutes in air, and further opticalmeasurement was made after annealing.In the annealing procedures, thetemperature was changed from lOOT) to650°C.
3. Results and DiscussionBefore irradiation, any 0A peaks
were not observed in the wavelengthrange of 6.2eV to 1.5eV for both typesof the samples. After irradiation,a relatively strong 0A peak at 5. leVwas clearly observed on the tail ofstronger 0A whose peak lies above 6.2eV, and a weak 0A shoulder was alsoobserved around 5. 8eV, which seems tobe due to the 7.6eV and the B'center
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JAERI-Review 95-019
respectively, lor each type of thesamples as shown in Fig. 1.
Figure 2 shows a typical continuouswave PL spectrum of SK1300 silica excit-ed by 5. leV light and the PLE spectramonitored at 4.3eV and at 2.7eV.A large PL peak at 4.3eV and a smallone at 2.7eV were clearly observed in thePL spectrum, and the PLE maxima for 4.3and 2.7eV PL were observed at the sameenergy. I t indicates that the PLbands of 4. 3eV and 2. 7eV are due to thesame defect center. I I is known thatthe Bz a band in extrinsic oxygendeficient silica glasses shows the weakand strong OA bands around 5.leV and 7.6eV, and also shows the strong and weakPL bands around 4.3eV and 2.7eV Ll—83.Therefore, the OA peak at 5. leV and thePL peaks at 4. 3eV and 2.7eV obtained inthis study can be tentatively attributedto the B z a band due to the oxygenvacancy ( = Si-Si = ). Figure 3 showsannealing curves of the OA peak at 5. leVof SK1300 and SK1310. T h e OA peak de-creased to the tail level of the OA bandabove G. 2eV, that is, the OA band above6.2eV was still observed even after anne-aling to 600X1, indicating that theorigin of the 5. leV OA band is differentfrom that of the band observed above6.2eV . This is consistent with theresult by Iroai et al.[2], if the bandabove 6.2eV is the 7.6eV band. I I isnoticed that the 5.leV OA band inducedby ion irradiation decreases afterthermal treatment above 100 °C in air.This behavior is in marked contrast tono bleaching of the 5. leV OA band afterannealing to 650T) in air in oxygendeficient silica glasses. T he oxygenvacancy of the Bt a band is formed inoxygen hypo-stoichiometric, that is,oxygen deficient silica glasses, whilein this study, oxygen vacancies of theextrinsic Bz a band induced by ionirradiation are formed in stoichioinctricsilica glasses. In stoichiometric
silica glasses, it is easy for recoil-ed oxygen to resume the original bandafter annealing at relatively lowtemperatures, while there are no extraoxygens to make silicon-oxygen-siliconbands in oxygen hypo-stoichiometricsilica glasses. Figure 4 shows theannealing behavior of the PL peaks at4.3eV for both types of the samples.The PL peaks show a monotomous de-crease up to the annealing at 350°C.After further annealing to 650T),the PL peak of SK1300 with higher OHcontent showed a weak maximum around480t while that of SK1310 with lowerOH content showed a constant value.
4. References[1] H. Nagasawa, Y.Hoshi and Y. Ohki,
Jpn. J. Appl. Phys. 26(1987)L554.[2] 11. Iinai, K. Arai, 11. Imagawa,
II. Hosono and Y. Abe, Phys. Rev. B38(1988)12772.
[3] R.Tohmon, H.Mizuno, Y.OhkiK. Sasagane, K.Nagasawa andII. llama, Phys. Rev. B39C1989) 1337
[4] R. Tohraon, Y. Shimogaichi,11. M i zuno, Y. Ohk i, K. Nagasawa,and Y.Hama, Phys. Rev. Lett. 62(1989)1388.
[5] II. N i sh i kawa, R. Nakamu ra,R.Tohmon, Y.Ohki, Y. Sakurai,K. Nagasawa and Y. llama, Phys. Rev.IM 1(1990)7828.
[6] II. N i sh i kawa, T. Sh i royama,R. Nakamura, Y.Ohki, K. Nagasawaand Y. llama, Phys. Rev. B45C1992)586.
[7] K. Awazu, H. Hosono and II. Kawazoe,SPIB2044(1993)78.
[8] Y. Sakurai, K. Nagasawa,II. Nishikawa and Y.Ohki, J.Appl.Phys.75(1994)1372.
- 119-
Fig. 4 Annealing behaviors of PL peaksat 4.3eV for SK1300 and SK1310.
Fig.2 Continuous wave PL spectra excitedby 5. leV light and the PLE spectra monitoredat 4. 3eV and at 2.7eV after irradiationfor SKI800.
Fig. 1 0A spectra of SK1300 and SK1310silica glasses before and after 5.5MeVFe'7< ion irradiation.
Fig.3 Annealing behaviors of UA peak at5. leV for SK1300 and SK1310.
JAERI-Review 95-019
5 . 1 5 In-Situ observation of Irradiation-InducedAmorphization in Transmission Electron Microscopy
Hiroaki Abe, Hiroshi Nararaoio and Chiken Kinoshita*Department of Materials Development, JAERI-Takasaki, Watanuki1233, Takasaki 370-12, Japan* Department of Nuclear Engineering, Faculty of Engineering,Kyushu University 36, Higashi-ku 6-10-1, Fukuoka 812, Japan
Introduction
Understanding of radiationdamage has become important notonly for the nuclear application butfor the materials development usingion beams. Under such irradiationenvironment, energetic particles, suchas ions and electrons, produce atomicdisplacements in solids. Number andspatial distribution of atomic displace-ments are characterized by the energytransferred to the primary knock-onatoms (PKAs) and by the PKA energyspectra. The crystalline-to-amorphousphase transformation under irradia-tion can describe the elementaryprocesses of radiation damage. In thiswork, the displacement thresholdenergy will be evaluated and the effectof cascades will be revealed throughthe analysis of irradiation-inducedamorphization in graphite.
Experimental Methods
Highly-oriented pyrolytic graphite(Union Carbide) was cleaved alongbasal planes to achieve thin films. Thethickness is estimated to be 200 nm,which is smaller than the range ofions. Irradiation was performed inTEM - Accelerator Facility 1) atTIARA. Electron irradiation was per-formed with fluxes of 1-5 x 1023
e/m2s at temperatures from 300 to600 K. The irradiated area was 0.6-1pirn in diameter. Irradiation with He+,C+, Ar+ and Ar2+ was done withaccelerating voltage from 200 to 300kV with ion fluxes from 1017 to 1018
ions/m2s at temperatures from 300 to840 K. The amorphization fluence isdefined as the fluence at whichdiffraction spots completely disappearand halo rings appear from theselected area of 0.2 / m in diameter onthe specimen.
Results and Discussion
Figure 1 shows a sequentialchange of the electron diffractionpatterns under irradiation with 400keV elections at room temperature.The irradiated area gradually loses itscrystallinity in (a)-(b), and becomesalmost amorphous in (c).
The amorphization fluence ( 0 / )was measured as a function of electronenergy. Hereafter, subscript e and /denote electron and ion irradiation,respectively. As shown in figure 2, thevalue of 1/0/ becomes measurable atthe electron energy of 140 keV andincreases with increasing electronenergy. The amorphization fluence indisplacements per atom (dpa), Ne, isdescribed as
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JAERI-Rcvicw 95-019
Ne = a(Ee, Ed) <Pea(Ee), (1)
where a, Ee and Ed are the displace-ment cross section, the incident energyof electrons and the displacementthreshold energy, respectively. Thevalues of a are calculated theoreticallyfrom the integration of the differentialcross section2) from Ed to the maxi-mum PKA energy. The value of Ed isevaluated as 27.1+1.1 eV fromequation (1) to minimize the standarddeviation of Ne. The value of Ne isevaluated as 0.46±0.08 dpa. The valueof Ed corresponds well to the litera-ture valued.
The amorphization fluence wasmeasured as a function of irradiationtemperature as shown in figure 3. Thevalue of N[ at room temperature isabout 0.2 dpa, which is much smallerthan Ne, and which is independentform mass and energy of ions. Theamorphization fluence increases withincreasing irradiation temperature.The apparent threshold temperaturefor amorphization (T1^1) increases withincreasing mass of projectile. Furtherinsight is the increase of T/fl withdecreasing £,• especially in Ar-ionirradiations.
Temperature higher than 400 Kcorresponds to the temperature whereinterlayer carbon molecules decom-pose to interstitials permitting theirrecombination with vacancies4). Thisindicates the accumulation of pointdefects is essential for the electron-induced amorphization process. Onthe contrary, one of the characteristicsof ion irradiation is the dense atomiccollisions along the path of the ions;i.e., cascades, the nature of which ischaracterized by the energy density 5).
Because graphite is a low-Z materialhaving large space between basalplanes, cascades in graphite are thelow density of atomic collisions wilhinlarge cascade volumes, resulting inlow-energy-density cascades. Theenergy densities of 300 keV He andAr cascades are roughly estimated as10'4 and 10"2 eV/atom, respectively.Such low-energy-density cascadesresult in the formation of subcascades.Unless the energy density varies overtwo orders of magnitude, the identicalvalues of iV; at room temperatureindicates amorphous cluster formationwithin subcascades. Heavier ionsproduce more subcascades closetogether, presumably resulting inhigher survival rate of amorphousclusters at high temperatures.
Conclusions
The TEM-Accelerator Facility atTIARA has been used to investigatethe irradiation-induced amorphizationin graphite. The displacement thresh-old energy was evaluated. Throughthe analysis of the fluence foramorphization, the significant role ofcascades is revealed.
References(1) H. Abe, H. Naramoto and C.
Kinoshita, Mat. Res. Soc. Symp.Proc. 373, 383 (1995).
(2) W.A. McKinley and H. Feshbach,Phys. Rev. 74, 1759 (1948).
(3) T. Iwata and T. Nihira, J. Phys.Soc. Jpn 31, 1761 (1971).
(4) B.T. Kelly, 'Physics of Graphite'(Applied Science Publishers Inc.,1981).
(5) P. Sigmund, Appl. Phys. Lett. 25,169 (1974) and 27, 52 (1975).
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JAERI-Review 95-019
(c)
U«ig
Figure 1. A sequence of selected area electron diffraction patterns (SAEDs)showing irradiation-induced amorphization in graphite irradiated with 400 keVelectrons with fluence of (a) 2.7 x 1026 e/m
2, (b) 4.4 x 1026 e /m2 and (c) 5.6 x1026 e/m2.
0 100 200 300 400 500
Electron Energy [keV]
Uof
nr 3
8 2
3
400keV e200keV He300keV C250keV C600keV Ar500keVAr.400keVAr^300keVArffllE?e
Ar
600
20
15
i° /,v:
10
3c§oCD
200 400 600 800
Irradiation Temperature [K]
Figure 2. Electron energy depen-dence of the amorphization fluence(<Pea) in graphite at room tempera-ture.
Figure 3. Temperature dependenceof the amorphization fluence (<pa)in graphite irradiated with ions andelectrons.
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JAERI-Review 95-019
5. 16 Y B a 2 C u 3 O Films I r r adi at e d"by" M n "*" I o n s
Y. Kazuinata, S. Yamamoto and H. NaramotoJapan Atomic Energy Research Ins t i tu t e
Improvement of criticalcurrent density is essential inorder to use high Tc superconductor.Many experiments [1] have beencarried out to increase cri t icalcurrent density ever since high Tcsuperconductors became available.Effective improvement has beenachieved through control of theflux creep by the lat t ice defectsfor ordinary superconductors. Asimilar method for improvement hasbeen also applied to high Tcsuperconductors.In the process for the improvement,i t is necessary to understand theinteraction between vortices andlattice defect. The interaction willbe simplified by a regular array oflattice defects. The purpose of thisexperiment is the study of theinteraction between vortices and aregular array of lattice defects.
The preparation of a regulararray of lattice defects is tried bythe method as shown in Fig.l. A 1000Cu-mesh, which is usually used by anelectron microscope experiment, wasput on the surface of a YBa2Cu30.iCthin film. The mesh with the widthof 3 mm is a grid made of Cu thinmetal, composing of 15 #m holesand of bars of a width of 15 /zm Cuthin metal. When energetic ions werebombarded from above the mesh, theions passing through the hole of themesh irradiate a YBa9CUo0T thin filmand change i t p a r t i a l l y to aninsulator. The rest part covered byCu-bars of the mesh will remain as asuperconductor. Ideally a regular
'array of la t t ice defects should beexpected by this method, but
actually the part covered by Cu-barswere also evaporated. Therefore, asuperconducting ring with a 3mmdiameter and a width of 0.5mm bringsfollowing r e su l t s in th i sexperiment. Ion irradiat ion werecarried out by 400 keV Mn+ and thefluence was 1.3xl015 MnVcm2.
(a)Ion Beam
Cu-mesh
f"! •"": '"'I f'"1 i"'
15/im
Fig.l(a) Experimental arrangement toobt.in a regular array of la t t icedefects.(b)Expansion of 1000 Cu-mesh.Cu-bar. has a width of 15 fim. andholes 15 fun square each.
Temperature dependence ofmagnetization (M-T curve) in a 100
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JAERI-Review 95-019
gauss and 1 kilo gauss field priorto and after irradiation are shownin Fig.2 and 3, respectively. Inthese figures, zero field cooling(ZFC) and field cooling (FC)magnetizations are shown. FCmagnetizations are nearlytemperature independent below Tc andare shown as horizontal lines nearby0 emu/cm3. In a 100 gauss field ZFCmagnetization has a convex curvatureprior to irradiation but change aconcave one after irradiation. Thevalues of ZFC magnetization afterirradiation decrease to 0.5 and 0.3times to these prior to irradiationin a 100 gauss and 1 kilo gauss,respectively.
M - T curves (YBCO films)
0
£-Si -10000
1-Si
§ -20000
tizat
§1-300005
, t , i 1 t > i 1
FC . , • < /
, - - • • ' " ' /
....•'•• Z p C ;•
, - • • • • • "
y_y Irrad.
/
. . • • • '
/ Unirrad.^ ^ H = 100G
0 50Temperature (K)
100
Fig.2 Temperature dependence ofmagnetization in a 100 gauss field.
M - T curves (YBCO films)
of
j j -20000
•2.1^-40000Q
CO
! -60000-
-80000(20
- / ' 2PO/". •••" Irrad. / '
/ Unirrad.
/ H
-
-
= 1 kG
100Temperature ( K )
Fig.3 Temperature dependence ofmagnetization in a 1 kG field.
The hysteresis curves(M - Hcurves) at 5 K are shown in Fig,4.The reduction of magnetization byirradiation is also seen in thisfigure. From the width of M-H curvesthe critical current density (Jc) iscalculated by the followingequation,Jc=20AM/a[l-(a/3b)]where a and b are the width and thelength of .the specimen; b>a). Theresults of the calculation is shownin Fig. 5. The reduction of Jc,especially at high temperatures,after i r radiat ion is quitesignificant.
M - H curves (YBCO films)[x105]
-50000 0 50000
Magnetic field (gauss)
Fig.4 Hysteresis Curves at 5 K.Critical current density
Magnetic field (gauss)
Fig.5 Jc from above 5,20,40,70 and80K.
Next step to obtain a regularpattern of la t t ice defects is now inprogress, although the in i t ia l t r i a lfell in vain.
References1)H.W. Weber, Physica C185-189(1991) 309, and references therin.
- 1 2 5 -
JAERI-Rcvicw 95-019
5 . 1 7 Formation Process of Defect Clusters in MgAlz04
under Displacive and Ionizing Irradiation
Chiken Kinoshita1, Kazuhiro Yasuda1, Yoshiaki Watanuki1, Hiroaki Abe2 and Hiroshi Naramoto2
department of Nuclear Engineering, Kyushu University, Fukuoka 812-81, Japan2 Department of Materials Development, Japan Atomic Energy Research Institute-Takasaki,
Takasaki 370-12, Japan
1. Introduction
Ionizing irradiation has been believed to play an
important role for the clustering of point defects in ionic
crystals, because of changes in the nature of point defects,
such as their charge states and mobilities. Zinkle [1]
recently reported that few dislocation loops were formed
in ionic crystals such as MgAl2O4 under high energy ion
irradiation where the ratio of electronic and nuclear
stopping powers {SJSn) was higher than 10 and pointed
out the importance of the parameter of S^S,, for the
clustering of point defects in ionic crystals. Kinoshita el
al. [2], on the other hand, observed no suppressive
formation of defect clusters in MgAl2O4 under concurrent
irradiation with 3 OkeV ions and 1 MeV electrons where
the value of S^S,, was much higher than Zinkle's
criterion. The purpose of the present study is to clarify
the difference between Zinkle's and Kinoshita's results and
the effect of ionization under displacive and ionizing
irradiation for the formation process of defect clusters in
MgAl2O4.
2. Experimental
Disks of MgAl2O4 were thinned by ion-milling
with 6 keV Ar+ ions and annealed in air to remove defect
clusters and Ar atoms induced by the ion-milling. The
specimens were subjected to concurrent irradiation at
temperatures from 870 to 1070 K with a homogeneous
ion beam and a focused electron beam in a transmission
electron microscope combined with two ion accelerators
in Takasaki Ion Accelerators for Advanced Radiation
Application (TIARA) at Japan Atomic Energy Research
Institute (JAERI). Projectile particles were H+, He+, O+
Fig. 1 Microslructurc in MgAl2O4 irradiated at 870K. with300keV He+ ions and 200 keV electrons. The inside and theoutside of the broken circle were subjected to concurrentirradiation with ions and electrons and to irradiation solelywith ions, respectively.
Fig. 2 Microstructure in MgAl2O4 irradiated at 870 K with300 keV O+ ions and 200 keV electrons.
- 1 2 6 -
JAERI-Review 95-019
and Ar+ ions with energy of 300 keV and electrons with
energy of 200keV to provide a wide range of SJSa.
Some of the annealed disk specimens were also irradiated
with 100 to 400 keV electrons at 300 to S00 K.
3. Results and Discussion
Fig. 1 is one of typical examples of bright-field
images showing microstructural evolution in MgAl2O4
irradiated at 870 K with 300 keV He+ ions and 200 keV
electrons. The inside of the broken circle was subjected to
concurrent irradiation with a focused electron beam and a
homogeneous ion beam, and the outside of it was
irradiated with only ions. Voids show up their contrasts
both inside (Sc/Sn=720) and outside (S^S^ISO) the
electron beam, and the size of voids inside the beam is
much larger than that of the outside. Another example on
microstructural evolution is shown in fig.2 for the
concurrent irradiation with 300keV O+ ions and 200keV
electrons. In this case, dislocation loops were formed
instead of voids shown in fig. 1, although the formation
of loops was suppressed inside(Se/Sn=6) the electron beam
comparing with that of the outside(Se/Sn=140). Similar
concurrent irradiation was performed with Ar+ or H"1" ions.
Summarizing the results of the present work and those
published by Zinkle and Kinoshita et al., one can realize
that dislocation loops are formed in the regions where the
values of S^Sj, are higher than the Zinkle's criterion
(Se/Sn=10) and that voids are preferentially formed in the
regions with higher values of S^S^
The annealed specimens of MgAl2O4 were also
irradiated solely with 200keV electrons. Fig.3 shows a
typical example of bright-field micrographs at 1070K
together with the relative concentration of atoms
examined by the energy dispersive X-ray spectroscopy
(EDX). Large voids are seen inside the electron beam, and
the relative concentration of Mg and O atoms decreases
inside the electron beam. Zn atoms might be introduced
in the specimen during annealing in an electronic furnace.
The results on the microstructure and the profile of
atomic concentration in fig.3 suggest that Mg and Zn
atoms preferentially diffuse to the outside of the electron
beam through the electronic excitation or the radiation
induced diffusion, because the 200keV electrons seldom
produce displacements of atoms in MgAl2O4. The
diffusion of cations to the outside of the electron beam
causes enrichment of vacancies inside it induce to the
formation of voids. Under the concurrent irradiation with
- 1 2 7 -
ions and electrons, such cation diffusion (or enrichment of
vacancies) causes the voids formation or the suppression
of dislocation loops depending on the irradiation
condition. The local density energy deposition by ions,
which depends on the mass of the ions, presumably
affects the microstructural evolution, though the detail
discussion requires further experiments.
(b)
.1000 0 500
Distance [nm]
1000
Fig. 3 Microstructure in irradiated at 1070K with 200kcVelectrons (a) and the relative concentration profile of atomsexamined by EDX along the broken line in the micrograph(b).
4. References
[1] S.J. Zinkle, Nucl. Inst. and Meth. B91 (1994) 235.
[2] C. Kinoshita et al., J. Nucl. Mater. 219 (1995) 152.
JAERI-Rcview 95-019
6. Materials Analysis
6.1 Measurements of Hydrogen Contents in Boron Films Produced
during Decaborane-based Boronization in JT-60U
MjSaido, J.Yagyu, S.Yamamoto, P.Goppelt-Langer, Y.Aoki,
H.Takeshita and H.Naramoto 131
6.2 Development of Elastic Recoil Detection Analysis Using
Heavy Ions — Simultaneous Detection of H and He
by Means of ERDA Technique Using 1ZC Ions —
S.Nagata, T.Hasunuma, K.Takahiro, S.Yamaguhi, S.Yamamoto,
P.Goppelt-Langer, Y.Aoki, H.Takeshita and H.Naramoto 134.
6.3 Studies on the Processes of Atomic Adsorption and Desorption
at the Solid-Liquid Interface by In-situ RBS Technique
K.Morita, J.Yuhara, R.Ishigami, B.Tsuchiya. S.Yamamoto,
P.Goppelt-Langer, Y.Aoki, H.Takeshita, H.Naramoto and K.Saitoh • • 136
6.4 Study of Charge States of Fast Ions In Single Crystals
H.Kudo, T.Fukusho, A.Tanabe, T.Ishihara, Y.Aoki, S.Yamamoto,
P.Goppelt-Langer, H.Takeshita and H.Naramoto 138
6.5 High Resolution L X-ray Spectra of Fe by 0.75 MeV/u H and He
Ion Impact
K.Kawatsura, R.Takahashi, H.Kageyama, T.Awata, T.Nakae,
A.Nishihata, Y.Nakai, S.Arai, Y.Aoki, S.Yamamoto, H.Takeshita,
P.Goppelt-Langer, H.Naramoto, T.Kambara, M.Oura, T.Papp, Y.Kanai,
Y.Awaya, Y.Horino, Y.Mokuno and K.Fujii 140
6.6 Analysis of Radiation Effect in Nuclear Materials by PIXE-
and RBS-Channeling
K.Kawatsura, T.Nakae, N.Shimatani, T.Awata, A.Nishihata,
R.Takahashi, Y.Nakai, T.Nomura, H.Kageyama, S.Arai, Y.Aoki,
S.Yamamoto, H.Takeshita, P.Goppelt-Langer, H.Naramoto,
Y.Horino, Y.Mokuno, K.Fujii, T.Mitamura, M.Terasawa,
H.Uchida, K.Koterasawa and N.Masuda 142
6.7 Effect of Nuclear Force upon Elastic Scattering and Its
Application to Elemental Analysis of H, D and 0
Y.Kido, T.Nishimura, Y.Furukawa, P.Goppelt-Langer,
S.Yamamoto and H.Naramoto 144
6.8 ERDA and RBS Using High Energetic Heavy Ions
P.Goppelt-Langer, S.Yamamoto, Y.Aoki, H.Takeshita and
H.Naramoto 146
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JAERI-Review 95-019
6.9 Stopping and Straggling of I5N Ions at 6.4 MeV
P.Goppelt-Langer, S.Yamamoto, Y.Aoki, H.Takeshita and
H.Naramoto 148
6.10 On-site Analysis of S'V+ Implantation into Sapphire
Using Dual Beam System
H.Naramoto, Y.Aoki, S.Yamamoto, H.Takeshita and
P.Goppelt-Langer 150
6.11 Ion Beam Analysis of Diamond Crystal Implanted with
400 keV 39K+ Ions
D.Rueck, M.Gan, S.Yamamoto, Y.Aoki, P.Goppelt-Langer,
H.Takeshita and H.Naramoto 153
6.12 Analysis of Hydrogen in Nb/Cu Multilayers Using Ion Beams
S.Yamamoto, P.Goppelt-Langer, Y.Aoki, H.Takeshita and
H.Naramoto 155
6.13 Depth Distribution Analysis of Hydrogen and Deuterium
in Nickel by ERDA
T.Mitamura, M.Terasawa, K.Arashi, L.Liu, S.Yamamoto,
P.Goppelt-Langer, H.Takeshita, N.Aoki and H.Naramoto 158
6.14 Nuclear Reaction Analysis of Carbon in C-ion Irradiated GaAs
K.Kuriyama, T.Kato, K.Sakai, S.Yamamoto, A.Aoki, H.Takeshita
and H.Naramoto 160
6.15 Study on Mineral Alteration -Analysis of Initial Stages
of Hydrothermal Alteration-
T.Ohnuki, T.Sato, H.Isobe, S.Yamamoto, P.Goppelt-Langer,
Y.Aoki, H.Naramoto and T.Murakami 163
6.16 Ion Beams Irradiation Experiments Combined with
Positron Spectroscopy
S.Okada, M.Hasegawa, A.Kawasuso, S.Masuno, M.Tabata
and M.Suezawa 165
6.17 Observation of the Initial Stage of Laser Ablation
A.Miyashita, T.Ohyanagi, O.Yoda and K.Murakami 167
6.18 Pulsed Laser Ablation of Silicon: Observation of
Particles Emitted from Si Surface and Sputtering
Phenomena Induced by Laser-ablated Particles
T.Ohyanagi, A.Miyashita, K.Murakami and O.Yoda 170
6.19 Real Time RHEED Observation during Carbon Thin Film
Growth by Ion Beam Deposition
H.Ohno, Y.Aoki and S.Nagai 173
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6 . 1
JAERI-Review 95-019
Measurements of Hydrogen Contents in Boron Films
Produced During Decaborane-based Boronization in JT-60U
Masahiro SAIDOH, Jun-ichi YAGYU, Shunya YAMAMOTO*,
Peter GOPPELT-LANGER*. Yasushi AOKI*, Hidefumi TAKESHITA*
and Hiroshi NARAMOTO*
Department of Fusion Facility and *Department of Material Development,JAERI
IntroductionIn JT-60U boronization using decaborane has
been carried out once in a year since July 1992
in order to reduce impurities, particularly
oxygen impurity in plasma. Boronization,
which is an in-situ boron coating on the plasma
facing surfaces in the tokamak, has been first
applied to the TEXTOR tokamak using a mixed
gas of diborane (BjH^ and heliumfl]. Since
diborane is highly toxic and explosive, we have
chosen decaborane (B10HM), a less hazardous
solid at room temperature, as an alternative
borane source for boronization[2]. It is required
to clarify the properties of the coated boron
films to understand their effects on the plasma
performance. Evaluation of hydrogen content in
the films is particularly important, since it
directly affects the particle controlling processes
in JT-60U plasma after boronization. Therefore
we have performed the measurement of
hydrogen content using 3MV tandem
accelerator. Two analyzing methods are used.
One is the resonance nuclear reaction analysis
(RNRA) method, the other is the elastic recoil
detection analysis (ERDA) one.
Experimental and results1) Resonance nuclear reaction analysis
(RNRA) method
For hydrogen detection the following reaction
is applied:1SN + lH— l2C + "He + 4.43 MeV y-ray (1)
Nuclear reaction expressed in eq. (1) shows
an isolated resonance peak around 6.4 MeV so
that the depth profile of the hydrogen content in
the film can be obtained by changing the
incident energy of 15N-beam[3]. Figure 1 shows
the results of the hydrogen depth profiles for the
various samples. In the figure the indicated
depths, lOOnm and 210nm, are obtained from
the SEM observation of the cross section of the
boron films. When we take the stopping power
of nitrogen in boron as 8.8 MeV/(mg/cm2), the
density of the boron film can be evaluated to be
around 1.3 g/cm3 which is about 60% of that of
a B/p-2 (Total)a B/Fe-3(T0tal)
6.3 6.4 6.S 6.6 6.7 6.8 6.9 7
Energy (MeV)
Fig. 1. Hydrogen dcplh profiles of boron films on
graphite and iron and of amorphous Si. Hydrogen
detection is made using resonance nuclear reaction
between incident beam of I5N and hydrogen.
- 1 3 1 -
JAERI-Rcview 95-019
[ Current integrator | - j Counter
absorber foil
Detector
Amplifier I—j Preamplifier \-T SiAS 1
Fig. 2. Experimental setup of elastic recoil detection
analysis.
boron crystal. As a reference sample for
hydrogen content, we used an amorphous Si
containing 20 atomic % of hydrogen, of which
data are also shown in the figure as A-Si. The
hydrogen contents for B/Fe-3 and B/Fe-4
samples are obtained to be 13.8 and 15.7 atomic
%, respectively.
2) Elastic recoil detection analysis (ERDA)
method
Figure 2 shows the experimental setup of the
ERDA method using high energy heavy ions
such as oxygen and nickel (HE-ERDA). Three
different ion beams, 8 MeV 16O*\ 16 MeV 16O*
and 30 MeV 58Ni9t are used for the incident
beam. The elastically recoiled particles, such as
hydrogen and deuterium are detected by the
Si-detector and the depth profiles of the recoiled
particles are obtained by their energy analysis.
Figures 3 and 4 show the ERDA spectra from
boron coated iron and graphite using 16 MeVX6O* and 30 MeV ^Ni9*, respectively. It is
clearly seen from Fig. 3 that the hydrogen and
deuterium are clearly separated in this
spectrum.When we use 30 MeV "Ni9*, boron
is also recoiled and detected so that we can
obtain the hydrogen content from the
comparison of these two yields of hydrogen and
boron as follows:
roo * M <oo «o
Channel number
Fig. 3. HE-ERDA spectra of boron films on graphite
and iron. Incident beam 16 MeV ^O3*.
1000
800
2 600
400 H
200
I""
i
1
30MeV " N i " —
Hydrogen
Il
11I
11 1[| I
I |** L i
• (3:H c210nrr
>n Fe) -
• Boron -
I
'V
200 400 600
Channel number800 1000
Fig. 4. HE-ERDA spectrum of boron film on iron.
Incident beam 30 MeV 58Ni^.
C H : CB = #CH j / m,,)2
: #CB/(ZB(m1 + rnB)/mB)2 (2)
where CH and CB are the concentrations, #CH
and #CB are the yields, Z, and 7^ arc the atomic
numbers and m,, and mB are the atomic masses
of hydrogen and boron, respectively, and mx is
the incident ion mass. Using eq. (2) the
hydrogen contents for B/Fe-3 and B/Fe-4
samples are obtained to be 9.2 and 10.9 atomic
%, respectively, which are smaller than those
from RNRA. The different values between the
two might come from the incorrect value of
hydrogen content of amorphous Si which is
used as a reference sample, since in HE-ERDA
method the hydrogen content can be obtained
only using eq. (2) without any reference
- 132 -
JAERI-Review 95-019
samples.
References
[1] H. G. Esser, H. B. Reimer, J. Winter and
D. Ringer, Fusion Technol. 1,791 (1988)
[2] M. Saidoh, H. Hiratsuka, T. Arai,
Y. Neyatani, M. Shimada and T. Koike,
Fusion Eng. Des. 22, 271 (1993)
[3] W. A. Lanford, Nucl. Instrum. Methods
B66, 65 (1992)
- 1 3 3 -
JAERI-Rcview 95-019
6 . 2 Development of Elastic Recoil Detection Analysis
Using heavy ions. -Simultaneous Detection of H and He
by Means of ERDA Technique Using 1?C Ions-
Shin ji Nagata, Tosikatu Hasunuma, Katumi Takahiro, Sadae Yamaguchi
Syunya Yamamoto*, P. Goppelt-Langer*. Yasusi Aoki*.
Hidefumi Takesita* and Hiroshi Naramoto*.
Institute for Materials Research, Tohokii University
*JAERI, Takasaki Establishment
1. Introduction
In order to study the hydrogen-helium
interaction in solid, it is necessary
to know the hoth depth profiles of II
and He simultaneously. One of the most
frequently used methods in depth pro-
filing of hydrogen isotopes is ERD
analysis technique using He ions(l).
By applying heavier projectiles such
as 12C, simultaneous detection of II
along with He is possible, and the
depth resolution can be further
improved. This report presents exper-
imental depth resolutions in the re-
flection geometry and typical results
of simultaneous measurement of II and
He depth profiles in the transmission
geometry.
2. Experimental and results
We measured experimentally the depth
resolution for the reflection ERD
analysis at several sample depths in
the case of 5.7 MeV I2C incident ions.
liRD spectra were taken from a 3
layered sandwich sample consisting of
20 nm and 40 nm Ni layers succesively
deposited on a Si wafer with high
smoothness. The surface of the top-
most Ni layer as well as Ni/Ni and
Ni/Si interfaces always contained a
contaminant hydrocarbon layer of 1-20
x 10lr'at./cm2. Examples of the mea-
sured spectra are shown in Fig. 1.
The energy spread of hydrogen peaks
A H a can be determined into depth
resolution A x using the effective
stopping power Soft as A x - A E d /
S C(t . Comparison between experimen-
tal depth resolution and theoretical
calculations at several sample depths
are now in progress.
The simultaneous detection of II along
with He were made on the Tillo. nir>
film of 2. [fim thickness during 10
keV He implantation at transmission
geometry. Examples of transmission ERD
spectra in the case of 4.5 MeV IZC
projectiles are shown in Fig. 2. The
peak at 710ch represents the recoiled
He and the intensities below 420ch
corresponds to the recoiled II. Accord-
ingly, separation between He and II
depth profiles is satisfactory. The
intensity of He peak as well as II con-
centration near the projected range
- 134-
JAERI-Review 95-019
of the implanted He increase gradu-
ally with increasing of implantation
dose. This result shows thai the ERD
analysis using 12C beam is very use-
ful to study the He—II interactions in
solids(2).
References
(1) S. Nagata, S. Yamaguchi, Y. Fujino
Y. Hori, N. Sugiyama and K. Kaniada,
Nucl. Instr. Meth., B6(1985)533-537.
(2) S. Yamaguchi, K. Ozawa. Y. Nakai
and Y. Sugizaki, JAERI-M 82-116(1982)
p. 1-73.
072525.ERD500
400 -
300 -
200 -
100 -
co
100 ZOO 300
072519.ERD
400 500
4UU
350
300
250
200
150.
100
SO
n
-
-
-
-
-
-
-V
-------i i
200 300 400
Channel Number
500 600
Fig,
a 11
0 =
1 ERD spectra of 5.7 MeV I2C for
-Ni-H-Ni-Si sample (a) a = 12.5 °
20° , (b) a -- 15 ° , 0= 30° .
:iKI 400 600
Dclcclcd Energy (kcV)
Fig. 2 ERD specra of 4.5 MeV 1ZC for
a Tillo. inn film during 10 keV He imp-
lantation.
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JAERl-Review 95-019
6 . 3
Studies on the Processes of Atomic Adsorption and Desorptionat the Solid-Liquid Interface by In-situ RBS Technique
K.Morita1, J.Yuhara1, R.Ishigami1, B.Tsuchiya1, S.Yamamoto2,
P. Goppelt-Langer2, Y.Aoki2, H.Takeshita2, H.Naramoto2, and K.Saitoh3
^•Dept.Cryst.Sci., Nagoya University,2Takasaki Establishment, JAERI,3National Indust. Res. Institute, Nagoya.
The aim of this study is to developthe experimental system for measuring,by in-situ RBS technique, the depthdistribution of heavy impurity atomsadsorbed at the inner surface of a thinfilm wall of a liquid container, which aredilutely dissolved in a liquid container,which are dilutely dissolved in a liquidspecimen, and for determining the rateconstants of their adsorption anddesorption at the solid-liquid interface.In order to achieve the aim of this study,it is necessary to prepare a stable thinfilm specimen which can isolate thevacuum system for the RBSmeasurement from the impurity-dissolved liquid. Moreover, it isnecessary to determine the energy rangeof probing He+ ion beam enabling thedetection of adsorbed species whichdepends on their mass and thickness ofthe thin film wall.
In this report, we describe themethod to prepare the thin wall windowof the silicon film with a SiC>2 surfacelayer and the performance of the siliconwindow of a liquid container, in whichXe gas of one atmosphere is enclosed,against the bombardment of 9MeV He+ion beam for the RBS measurement.
The thin silicon window wasfabricated using preferentially slowetching of heavily B-implanted silicon. Asilicon wafer of 0.2mm in thickness and10mm in diameter was implanted with4MeV B+ ions, of which the projectedrange is 5.5 im and hereafter was
annealed for an hour at 950°C in orderto reduce the radiation damageintroduced by the B implantation and toproduce the SiO2 layer at the surface.The unimplanted and unmasked surfaceof 3mm in diameter was etched. Thesilicon wafer was used for the thin wallwindow of the liquid container, which isshown schematically in Fig.l Thecontainer was made of stainless steeland aluminum.
For testing the tolerable strength ofthe thin silicon window against thepressure difference of one atmosphereunder irradiation of the probing He+ ionbeam, the container was placed in aconventional UHV chamber which isconnected to a beam line of 3MeVTandem accelerator in the TIARAfacilities. When the Xe gas of oneatmosphere was enclosed in thechamber, no leakage of Xe gas wasdetected. The thin silicon window wasirradiated with a 9MeV He++ ion beamof 0.6mm in diameter at an ion flux of1.9xlO13/cm2s in perpendicular to thesurface. He ions backscattered from thesilicon window were detected with anannular-type silicon surface barrierdetector. A typical RBS spectrum of9MeV He"*"1" ions from the thin siliconwindow is shown in Fig.2. It is.clearlyseen from Fig.2 that a broad peakbetween the channel numbers 550 and680 represents the backscattering fromXe atoms and large three peaksrepresent that from the silicon window.
- 1 3 6 -
JAERI-Review 95-019
The scattering from the Al backplateappears at low energies of a small peakat the channel number of 275. Thethickness of the Xe gas target, estimatedfrom the broad Xe peak on theassumption that the Xe gas pressure isone atmosphere, was 4.5mm, which isvery consistent with the real measurefrom the back surface of the thin siliconwindow to the surface of the Albackplate. Therefore, the Xe gaspressure was concluded to be kept at
silicon window
one atmosphere. The thin siliconwindow was continuously irradiatedwith 9MeV He+ + ions up to3.1xlO17/cm2. The RBS energy spectrumobtained after the irradiation was thesame as the first one in Fig. 2, whichindicates that the thin silicon window istolerable against such a heavyirradiation under the pressuredifference of one atmosphere. Furthertesting of the container filled with wateris planed in the next experiment.
aluminium
stainless steel
aluminium 30mm(|)inlet of Xe gas
O-ring
250mm
Fig.l A schematic drawing of a liquid container in whichXe gas of one atmosphere was enclosed for testing.
80000
60000
§ 40000oo
20000
9 MeV H e + W Si (5.5 urn) / Xe (4.5 mm) / Al0 =180°
200 400 600Channel Number
800
Fig.2 A RBS energy spectrum of 9 MeV He++ ion beam froma container filled with Xe gas of one atmosphere.
- 1 3 7 -
JAERI-Rcvicw 95-019
6 . 4 Study of Charge States of Fast Ions in Single Crystals
H. Kudo, T. Fukusho, A. Tanabc,T. Ishihara, Y. AokP,S. Yamamoto2, P. Goppelt-Langer2, H. Takeshita2, H. Naramoto2
Instututc of Applied Physics, University of Tsukuba, JAERI, Takasaki2
Introduction
Under channeling incidence conditionsof fast ions, the repulsive ion-atominteraction deflects the ions away from thealigned atoms, so that the atoms in thecrystal are more effectively shadowed withincreasing depth. This is actually the initialstage of ion channeling.
High-energy (kcV) secondary electronyield induced by fast ions reflects the high-energy shadowing effect which is difficultto observe by other methods. One of theimportant applications of ion-inducedelectron spectroscopy combined with thechanneling technique is the determinationof charge states of fast ions in solids. Inthe past year, we have made progress inthe analysis method, and have successfullydetermined the charge states of 2.5- and3.5-MeV/u ions (2<Z<17) in glancingcollisions with atomic rows in Si.
Modified analysis of charge states
When the ion's nuclear charge isscreened by inner-shell electrons, theelectron yield in the channeling case isenhanced by two mechanisms, i.e., thereduced shadowing effect and the enhancedemission effect. The enhanced electronyield can be analyzed by comparing theratio of channeling to random yield to thosefor various ions of equal velocity. The"enhanced emission for the random casemust be also taken into account unless the
ions arc fully stripped, since it also affectsthe ratio of channeling to random yield. Itshould be noted that the latter effect, foundby several workers recently with 0-degreeelectron spectroscopy using gas targets,has been ignored in our previousanalysis. In a modified analysis, we havesuccessfully taken into account the abovetwo effects.
Figure 1 shows the effective chargesZeff (=ion's atomic number minus numberof capture electrons) for the 2.5 MeV/uions, obtained from the modified analysis.
12
-i—i—i—i—i—i—i—i—i—i—i—i—i—r
2.5-MeV/u ions
o Si<100>
2 '. 6 8 10 12 14 16 18
Fig. 1 ZaH obtained from the analysis
- 1 3 8 -
JAERI-Rcvicw 95-019
The numbers near the plots indicate theincident charge states of the ions. Figure 2shows similar results for the 3.5 McV/uions.
In contrast to the light ions, the electroncapture as well as loss occurs for the Si, S,and Cl ions. At2.5-MeV/u, Si*3+. S13+,and Cl15+ capture about 3 or 4 electrons,on the average, but Si7+, S7+, and Cl8+
lose 1 or 2 electrons. Therefore, we mayconclude that for the channeling case themost probable charges in the equilibrium,Zeq, are 8.2<Zeq<9.7, 8.6<Zeq<10.3, and9.1<Zeq<11.3 for 2.5-MeV/u Si, S, andCl, respectively. Similarly, it can be
12 -
10 -
3.5-MeV/u ions
o Si<100>• Si<H0> /
/
: h
' . IS t
" l 3 t »IO*
OlOt
8 8 t
/
/^.n^i-10
2 A 6 B 10 12 K 16 IB
Fig. 2 Zeff obtained from the analysis
concluded that 9.6<Zeq<11.3 and10.5<Zcq<11.9 for 3.5-McV/u Si and S,respectively.
The results also indicate that the numberof bound electrons in the limit of chargeequilibrium is greater than for the ionsunder random incidence conditions. Itappears reasonable that the values of Zeffare greater than Zi -10, i.e., the neon-likeelectronic core, unlike in the previousanalysis.
Conclusions
The charge states determined by thepresent method are characteristic of theions passing through a high-density regionof electrons near the atomic rows, whichhave never been approached experimentallynor theoretically. Similar analysis of chargestates in Ge crystals is now under way tostudy not only the material dependence, butalso the impact-parameter dependence ofthe charge states.
References
fl] H. Kudo, K. Shima, T. Ishihara,H.Takeshita, Y. Aoki, S. Yamamoto, and H.Naramoto, Nucl.Instrum. & Methods, B90(1994)533.[2] H. Kudo, T. Fukusho, T. Ishihara, H.Takeshita, Y. Aoki, S. Yamamoto, and H.Naramoto, Phys. Rev. A50 (1994) 4049.
- 1 3 9 -
JAERI-Rcvicw 95-019
6 . 5 High Resolution L X-Ray Spectra of Fe by 0.75 MeV/u H and He Ion Impact
Kiyoshi KAWATSURA, Ryohci TAKAHASHI, Hiroyoshi KAGEYAMA, Takaaki AWATA,
Takanori NAKAE, Atsushi NISHIHATA, Yoshihiro NAKAI, Shigeyoshi ARAI, Yasushi
AOKI*, Shunya YAMAMOTO*. Hidefumi TAKESHITA*, Peter GOPPELT-LANGER*,
Hiroshi NARAMOTO*, Tadashi KAMBARA", Masaki OURA", Tibor PAPP**, Yasuyuki
KANAI**, Yohko AW AY A**, Yuji HORINO***, Yoshiaki MOKUNO*** and Kanenaga
FUJII***
Faculty of Engineering and Design, Kyoto Institute of Technology,
* Department of Materials Development, JAERI,
** Atomic Physics Laboratory, RIKEN and
*** Osaka National Research Institute (ONRI), AIST
Introduction
Several experiments on L X-ray spectra using crystal
spectrometers have shown the phenomena of
extensive multiple ionization [1-3]. L X-ray lines
produced by heavy ion impacts have been observed
to be broadened and shifted to higher energies than
the corresponding lines produced by electron and
proton impacts. For heavy-ion impacts in the McV/u
range, these energy shifts have been attributed
experimentally and theoretically to multiple inner-
shell electron vacancies of the initial atomic
configurations produced by the heavy ion-atom
collisions. As L X-ray spectra contain much more
transitions than K X rays, a variety of line shifting
and peak broadening mechanisms can be added to
the complicated L X-ray spectra.
We have reported [2] that broad satellite peaks are
observed in the high energy side of the characteristic
L X-ray line in 3d transition metals (Cr, Mn, Fe and
Co) by MeV N and Ne ion impacts and the La\,2
lines are significantly shifted to the lower energy
side. The high energy satellites are considered to be
L hypersatellite and satellite lines arising from the
multiple electron vacancy production in the L, M
and N shells during heavy ion-atom collisions.
While, the process that caused the lower energy shift
in the La\,2 X-ray line is still unknown. Therefore,
we have measured highly resolved L X-ray spectra
from the Fe target produced by 0.75 MeV/u H and
He ions.
Experimental
The experiments with a beam of 0.75 MeV/u H+ and
He+ ions were performed at the JAERI-TIARA
accelerator facility using the 3 MV single-ended
electrostatic accelerator. The experimental setup has
been described in detail previously [2]. The ion
beam (5x5 mm2) was incident on a thick Fe target
normal to the surface. The X rays emitted at a take-
off angle of 45° were analyzed by a flat crystal
spectrometer with a RbAP(lOO) crystal (Rubidium
acid phthalate, 2d=2.6121 nm).
Results and discussion
Figure 1 shows the L X-ray spectra from a thick Fe
target produced by 0.75 MeV/u H+ and He+ ions,
respectively. In order to analyze the spectra
quantitatively, least-squares fits were performed
using a few pseudo-Voigt functions to represent the
gross structure. The quality of the fit was excellent
in both cases. The resulting peak centroid energies
for H and He impacts had same values which were
616 eV for Lx, 628 eV for Lr\, 704.9 eV for La 1,2 and
717.7 cV for LpM (Table 1). These values are in
good agreement with those of 615, 628, 705 and 718
eV given in the reference [4]. The average widths of
Lai,2 and Lpi are 6.5 and 12 eV for both projectiles.
The relative intensity, Lpi/Lai,2 for He ion impact is
twice as large as for H ion excitation. This result
suggests that multiple ionization is induced more
- 1 4 0 -
JAERI-Review 95-019
gLU
LU
F=
lilrr
- He+-*Fe
| Li?
\ :
11 1 '
- H+-*Fe -
• . . . . i . . . . i . . . . i
600 650 700 750X-RAY ENERGY (eV)
Fig.l L X-ray spectra of Fc produced by 0.75 McV/u
H+ and Hc+ ion impacts.
Table 1 Averaged centroid energies in eV for Fe L\,
Lr\, La\,i and ip i X-ray diagram lines produced by
0.75 McV/u H+ and He+ ions.
X-ray Transition Averaged ccntroid energy/eV
Present Ref. 4
References
[1] F.Hopkins, in: Methods of ExperimentalPhysics, edited by P.Richard (Academic Press,New York, 19S0), Vol.17, p.355.
[2] K.Kawatsura, K.Ozawa, M.Terasawa,K.Komaki and F.Fujimoto, Nucl. Instrum.Methods Phys. Res. B75, 28 (1993).
[3] V.Horvat, R.L.Watson and R.Parameswaran,Phys. Rev. A51_, 363 (1995).
[4] J.A.Bearden, Rev. Mod. Phys. 39, 78 (1967).
[5] I.P.Grant, B.J.McKenzie, P.H.Norrington,D.F.Mayers and N.C.Pyper, Comput. Phys.Commun. 2J., 207 (1980).
[6] K.G.Dyall. I.P.Grant. C.T.Johnson, F.A.Parpiaand E.P.Plummer, Comput. Phys. Commun 55,425 (1989).
[7] H.Kageyama, K.Kawatsura, RTakahashi,T.Awata, T.Nakae, S.Arai, T.Kambara,M.Oura, T.Papp, Y.Kanai, Y.Awaya,H.Takeshita, Y.Aoki, S.Yamamoto,P.Goppelt-Langer, H.Naramoto, Y.Horino,Y.Mokuno and K.Fujii, Proc. 3rd Int. Symp.Swift Heavy Ions in Matter (Caen, France,May 15-19, 1995).
Lx
IT,
Lal,2
2P3/2"3sl/2
2pi/2-3d3/2
616628
704
717
.9
.7
615628
705
718
significantly for He ion impact.
The measurement of I X-ray spectra from a Cu
target produced by 0.75 MeV/u H+ and He+ ions will
be performed soon at the TIARA facility to compare
the spectra produced by heavy ion impacts at the
RILAC of RIKEN. All of these I X-ray spectra are
also compared with the calculated ones by using the
multi configuration Dirac-Fock method (MC-DF
method) [5,6]. Preliminary calculation using the
MC-DF method (GRASP-code) suggests that the
broadening of the Lai,2 line to the lower energy is
attributed to one 2p p5-i one 3d electron vacancy
production [7].
- 1 4 1 -
JAERI-Review 95-019
6 . 6 Analysis of Radiation Effect in Nuclear Materials by PIXE- and RBS-Channeling
Kiyoshi KAWATSURA, Takanori NAKAE, Narutoshi SHIMATANI, Takaaki AWATA,
Atsushi NISHIHATA, Ryohei TAKAHASHI, Yoshihiro NAKAI, Terunari NOMURA,
Hiroyoshi KAGEYAMA, Shigeyoshi ARAK Yasushi AOKP, Shunya YAMAMOTO*,
Hidcfumi TAKESH1TA*. Peter GOPPELT-LANGER*, Hiroshi NARAMOTO*, Yuji
HORINO**. Yoshiaki MOKUNO**, Kancnaga FUJII**, Tohru MITAMURA***, Mititaka
TERASAWA***, Hitoshi UCHIDA***, Kcishi KOTERAZAWA*** andNobuhiko
MASUDA"**
Faculty of Engineering and Design, Kyoto Institute of Technology,
* Department of Materials Development, JAERI,
** Osaka National Research Institute (ONRI), AIST,
*** Faculty of Engineering. Himeji Institute of Technology and
**** Tatcho Chemical Co.. Ltd.
Introduction
In the radiation effect study with energetic ions, it is
necessary to earn.' out a microstructural analysis on
single crystals of nuclear materials by using PIXE
and RBS methods under channeling conditions
(PIXE-C and RBS-C) to explain depth profiles of
implants or impurities and transformed layers, and
radiation-induced defects.
We have investigated radiation-induced effects in
single crystals of type 304 austenitic stainless steel
(SUS 304) irradiated with 1.6 MeV He ions [1-4],
and radiation-induced defects and their annealing
behavior in single crystals of a-SiC(OOOl) [5.6] and
MgO(lOO) [7] implanted with 1.0 MeV Ni ions by
means of PIXE-C and RBS-C measurements. In this
report, we describe only the result of SUS 304
irradiated with a 1.6 MeV He ion beam up to the
doseof2.5xl0I7cnr2.
Experimental
A single crystal of type 304 stainless steel (SUS 304)
was grown by the modified Bridgman method at
Himeji Institute of Technology [2]. The quality of
the single crystals has been examined at the 2 MV
Van de Graaff accelerator facility at ONRI, Ikcda
and at the 3 MV single-ended electrostatic
accelerator facility at JAERI, Takasaki (TIARA
facility). Single crystalline specimens of (100),
(110) and (111) oriented SUS 304 were bombarded
with 1.6 MeV Hef ions incident 4° to the surface
normal at room temperature.
Results and discussion
Figure 1 shows the dose dependence of the
displacement atom ratio (DAR). The values of DAR
for (110) increase linearly and reach 0.1 at a dose of
2.5xlO17 cm"2. Those for (100) and (111) increase
more rapidly at the initial stage and reach 0.15 and
0.14 at the same dose, respectively. The dose
dependence for (110) is fairly different from the
above two orientations. We cannot conclude in this
stage if this difference is associated with the
specified orientation of atomic defects.
Figure 2 shows a part of the PIXE spectra from the
random orientations of SUS 304 single crystal with
(100), (110) and (111) surfaces before and after 1.6
MeV He irradiation of 2.5x 1017 cm"2. The K X-ray
yields from Cr, Fc and Ni atoms are confirmed to be
equal in all six spectra. The K X-ray yields from the
Si atoms increase by 20% for (110) and (110), and
by 15% for (111), respectively, after He irradiation,
and those from the S atoms only a few % for the
(100) and (110) surfaces. This enrichment of Si and
S atoms to the surface during ion irradiation is due
to radiation-induced segregation (RIS). Thus, the
PIXE-C method has proved to be a very sensitive
technique to investigate the RIS mechanism in single
crystal stainless steels [1-4].
- 142 -
JAERl-Review 95-019
n
Am
crs0<t 0.1
zUJSuija\na
1.6
O :
A :D :
of~.
Q W
E3
MeV He+ -^ SUS304
<100> o0 a<110> 0 Q
<m> ° nO D A
o n Aon ^
« AO D A8 A
. i . . • . I
0 1 2
DOSE/1017cnV2
Fig.l Dose dependence of the displacement atom
ratio (DAR) along the <100>, <110> and <111>
orientations in the RBS measurements for SUS 304
single crystal.
1.6MeVHe+->SUS304
1 2 3ENERGY/keVRANDOM, VIRGIN REGIONRANDOM. 2.5X1017 cm"2
References
[1] K.Kawatsura, T.Nakac, N.Shimatani,K.Maeda, S.Arai, T.Mitamura, M.Terasawa,H.hvasaki. H.Uchida. K.Kotera7awa,Y.Horino, Y.Mokuno, K.Fujii, M.Satou,M.Sataka, M.Imai and H.Maeta, Nucl. Instrum.Methods Phys. Res. §75, 367 (1993).
[2] T.Nakae, R.Takahashi, T.Nomura, Y.Nakai,H.Kageyama, N.Shimatani, T.Awata,A.Nishihata, S.Arai, K.Kawatsura, Y.Horino,Y.Mokuno, K.Fujii, Y.Aoki, H.Takeshita,S.Yamamoto, P.Goppelt-Langer, H.Naramoto,T.Mitamura, M.Terasawa, H.Uchida andK.Koterazawa, Int. J. PIXE 4, 193 (1994).
[3] T.Nakae, K.Kawatsura, R.Takahashi, S.Arai,T.Mitamura, M.Terasawa, H.Uchida.K.Koterazawa, Y.Horino, Y.Mokuno andK.Fujii, J. Nucl. Mater. 223, 210 (1995).
[4] K.Kawatsura, T.Nakae, RTakahashi, Y.Nakai,S.Arai, Y.Aoki, S.Yamamoto. H.Takeshita,P.Goppelt-Langer, H.Naramoto, Y.Horino,Y.Mokuno, K.Fujii, T.Mitamura, M.Terasawa,H.Uchida and K.Koterazawa, Proc. 12th Int.Conf. Ion Beam Analysis (Tempe, USA, May22-26, 1995).
[5] N.Shimatani, K.Kawatsura, S.Arai. T.Shiono,Y.Horino, Y.Mokuno, K.Fujii, H.Takeshita,S.Yamamoto, Y.Aoki and H.Naramoto, Nucl.Instrum. Methods Phys. Res., BjM, 529 (1994).
[6] N.Shimatani, K.Kawatsura, RTakahashi,S.Arai, Y.Aoki, S.Yamamoto, H.Takeshita,H.Naramoto, Y.Horino, Y.Mokuno andK.Fujii, Proc. 6th Int. Conf. SiC and RelatedMater. (Kyoto, Japan, Sept. 18-21, 1995).
[7] R.Takahashi, T.Nakae, N.Shimatani,A.Nishihata, K.Shiono, K.Kawatsura, S.Arai,H.Takeshita, Y.Aoki, S.Yamamoto,P.Goppelt-Langer, H.Naramoto, Y.Horino,Y.Mokuno, K.Fujii and N.Masuda, JAERITIARA Annual Report 1993 vol.3, JAERI-Review 94-005, pp.129 (1994).
Fig.2 PIXE spectra from the random orientation of
SUS 304 single crystal oriented to the (100), (110)
and (111) surface before and after 2.5xlO17 cm"2 He
irradiation.
- 1 4 3 -
JAERl-Review 95-019
6 . 7 Effect of Nuclear Force upon Elastic Scattering andIts Application to Elemental Analysis of H, D and O
Yoshiaki KIDO, Tomoo NISHIMURA, Yoshinori FURUKAWAFaculty of Science and Engineering, Ritsumeikan University
Peter GOPPELT-LANGER, Syunya Yamamoto,Hiroshi NARAMOTO
Department of Materials DevelopmentJAERI/Takasaki
[Introduction]Rutherford Backscattering Spectroscopy
(RBS) with MeV He ion beams provides apowerful and versatile tool to determineelemental compositions and crystalstructures from a top surface to a depth ofabout 1 \xm. RBS has an excellentcharacteristic that it enables us to deriveabsolute quantities of impurity elementswithout standard samples and also theirdepth profiles nondestructively. Its weakpoint is the poor sensitivities to lightelements. However, nuclear reactionanalysis including elastic scatteringenhanced by nuclear interactions coversthe above point to some extent.
In the present study, we have determinedprecisely the cross sections of resonantelastic scattering for MeV ions-impact onH, D and 0 and then performed theirquantitative analyses, which are generallyvery difficult for other techniques. Wefurther discuss how to improve theaccuracy of the above elemental analysis.
[Differential scattering cross sections]The elemental analyses of H and D were
made by detecting the particles recoiledinto forward directions using MeV He+
beams. This technique is frequently called"elastic recoil detection analysis(ERDA)".These recoil cross sections are stronglyenhanced by nuclear interactions due to
low coulomb barriers. In order todetermine the cross sections precisely, weused the standard samples which wereprepared by CH3
+ and CD3+ implantation
into Si substrates. Organic films areinadequate for their purpose, becausegas-like elements of H and 0 easily escapefrom the surfaces.
The resonant elastic scattering of 160(He,He)I60 has a sharp and strong resonancearound 3.034 MeV, which is applicable tooxygen analysis. We have also determinedthe scattering cross sections usingthermally oxidized SiO2 films. Thisresonant elastic scattering has strongenergy and scattering angle dependence asshown in Fig. 1. Thus one must measurethe scattering angle precisely and carefullyselect the incident energy.
[Application]The above elastic scatterings were
applied to following 3 types of samples;(l)a-Si(H) formed by CVD,(2)Ge/D/Si(100) prepared by EBdeposition followed by rapid thermalannealing, (3)YBa2Cu4O8.5/SrTiO3,NdBa2Cu307.s/SrTi03. Fig. 2(a) shows theRBS spectra from NdBa2Cu307.6/SrTi03
for 3.090 MeV He+ incidence andscattering angle of 170°. Fig. 2(b) is themagnified oxygen spectra in which thebackground from STO is subtracted. In
- 1 4 4 -
JAERl-Review 95-019
such oxygen analysis, the crucial point to'improve the accuracy is to best-fit the totaloxygen yield from the resonance instead ofoxygen peak height and to select theincident energy so that the He+ energy at
References1)Y. Kido, S. Miyauchi, 0 . Takeda,
Y.Nakayama, M. Sato and K. kusao,Nucl. Instrum. Methods B82( 1993)474.
2)T. Nishimura, Y. Kido, F. Wang, M.Badaye, Y. Yoshida and T. Morishita,the half depth of the film of interest
becomes close to the resonance energy of submitted to J. Appl. Phys.3.034 MeV.
3.069MeV He'* -> NdBaCuO/STO
Nd: Ba : Cu: 0 = 1.0:2.0:3.0:7.0Tc = 84 (K)
— Simulation—• Simulation. Experiment
Scattering cross section ,
100 150 200 250 300 350 400 450 500Channel number
>
4000
3500
3000
2500
2000
1500
1000
500
0
(b)
Oxygen
O (TOTAL)O (NBCO)
• ••- O(STO)o Experiment
Fig. 1. 16O(He,He)16O differential scatter-ing cross sections as a function of scatteringangle and incident energy.
Fig. 2. (a) Observed and best-fitted RBS
spectra from NdBa2Cu307_£/SrTi03 for 3.069
MeV He2+ incidence, (b) Magnified oxygen
spectra observed and best-fitted.160 165 170 175 180 185 190 195 200 205
Channel number
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JAERI-Review 95-019
6 . 8 ERDA and RBS using High Energetic Heavy Ions
P. Goppelt- Langcr, S. Yamamoto, Y. Aoki, H. Takeshita, H. NaramotoDept. of Materials Development, JAERI/Takasaki
Elastic Recoil Detection Analysis (ERDA)and Rutherford Backscattering Spectrometry(RBS) have been carried out using high ener-getic heavy ions as 160, "2S, and 58Ni at ener-gies between 0.5 and 1.0 MeV/amu. The aimof this project was the analysis of light andheavy elements with high depth resolutionand sensitivity. As reported earlier [1], thetechnique was successfully applied to the si-multaneous detection of elements rangingfrom H to C in thin layer samples. In thismeasurements a simple detector setup usingan aperture slit and a thin Mylar absorber foilcould be chosen. The spectra were energeti-cally separated over a range of a few 1000 A.If the ERDA technique is combined withRBS, light and heavy target elements can bemeasured simultaneously. Target elements inthe mass range of the projectile are excludedfor this simple ERDA setup. More recentmeasurements make use of a time-of-flightsystem consisting of a transmission channel-plate detector and a 450 mm2 surface barrierdetector at a distance of about 1.2 m. Thedetector is fixed at 45° scattering angle. Beameminence is limited two apertures to less than0.5°. In front of the detector an aperture slit
diilnm toil iipcnuic slitI!ii|<g/cin2 flight path
I in \ r - A SHI)
Fig. 1: dcicctor setup for ERDA using tiinc-of-flighland energy detection.
was placed to reduce the in-plane angularwidth of the detector, which is neccessarybecause of the large kinematic energy spreadin ERDA. The detector setup for ERDA andRBS using time-of-flight is shown in figure 1.Using this system the scattered particles areidentified by their mass. Simultaneously, thewhole mass range is covered by ERDA, un-ambiguously, over the whole depth range.
Fig. 2 shows a typical 2-dimensional spec-trum of time-of-flight vs. energy. This spec-trum has been taken using a 30 MeV 5SNibeam. The target was a 500 A thick V layeron Silicon. Obviously, there is an oxide layeronto the sample surface. All elements O, V,Si and Ni are clearly separated.
Time-of-flightFig. 2: 2-dimcnsional spectrum of timc-of-flight vs.energy. Sample is 500 A vanadium layer on a siliconsubstrate. Beam is 30 McV 5KNi.
16,Fig. 3 shows the spectrum of a 16 MeV Obeam scattered into 45° in forward directionon a Nb/Si multilayer structure. The thicknessof the layers is only 50 A and they are wellseparated. Projectile ions scattered on heavytarget elements have high detector yield andenergy and forward scattering RBS can beapplied simultaneously with high depth reso-lution. In forward scattering RBS the mass
- 1 4 6 -
JAERI-Review 95-019
separation is relatively poor and it is onlyapplicable for large mass differences in thetarget.
-tooEnergy [arb. units]
soo
Fig. 3: spectrum of forward scattered oxygen ionsscattered on Nb. Sample consisting of Nb/Si multi-layers of 50 A thickness.
Fig 4 shows the heavy ion RBS spectrum of aNb/Cu multilayer system, were the detectorwas placed at 180° (annular detector). The 16MeV 16O beam showed almost best results,regarding mass separation and depth resolu-tion. The spacing of the Nb/Cu layers is 50 A.The sample has been inclined to 70° relativeto the surface normal to achieve best depthresolution without interference between Cuand Nb backscattered ions.
In heavy ion experiments the beam effects arenot negligible [2]. A large amount of energyis deposited in a very thin layer. Sampleheating is most often a crucial parameter.Therefore, during the last experiments an ap-erture slit of 1 x 5 mm2 was used for the in-cicent beam instead of the circular apertureused before. Sample cooling should be ap-plied in further experiments.
§ 1 0 0 -
1 •
•3 50 •"3
n L
' I • I '
Nb/Cu 50 A x S
RBS 170/10
16 McV " 0 i111
illliifffli/ I ' ' I B L2 " Yfif '
I>u J .
-•
•
-
i k i i i iMil -200 400 600
Channel number800
Fig. 4: heavy ion RBS spectrum of a Cu/Nb multi-layer structure wit 50 A lavcr thickness.
References:
[1] P. Goppelt-Langer, S. Yamamoto, Y.Aoki, H. Takeshita, H. Naramoto, JAERITIARA Annual Report 3 (1993) 137
[2] R. Behrisch, Proc. IBA-12 conf.(1995) Tempe/AZ, to be published in Nucl.Instr. Meth. B
- 147 -
JAERI-Review 95-019
6600 6800Energy [keV]
6 . 9 Stopping and Straggling of 15N Ions at 6.4 MeV
P. Goppelt- Langer, S. Yamamoto, Y. Aoki, H. Takeshita, H. NaramotoDept. of Materials Development, JAERI/Takasaki
Stopping-powers and straggling in varioustarget materials have been measured for 15Nincident ions at 6.4 MeV using the well-known 'H(15N,aY)12C resonant nuclear reac-tion [1], Samples have been prepared usingelectron beam evaporation of thin layers ofSi, Ti, Ni, Cu, Nb, Pt and Au on H terminatedcrystalline silicon substrates under UHVconditions. The H monolayer remains stableat the silicon substrate during evaporation andion irradiation. The layer thicknesses wereranging from 500 to 3500 A. At this thicknessrange the energy straggling is between 15 and40 keV (a) and is the main contribution tothe measured width of the H profile. Surfaceroughness, interface quality and Dopplerbroadening are negligible. The nuclearstraggling (a) is comparable to the electronicstraggling. But, while electronic stragglingcan be assumed to be of Gaussian shape, thenuclear straggling is peaked much narrower,but has long tail from close encounter colli-sions, which is the dominant contribution tothe straggling. This tail does not contribute tothe width of the 15N measurement. The meas-ured width is affected by electronic stragglingonly. A crucial point in the straggling meas-urement is the diffusion of the H layer duringirradiation. In this experiment the H wasbonded strongly on the Si substrate andshowed to be stable under irradiation. In theexperiment of Briere et al. the samples werekept at low temperature, which may havesimilar effect. The measured H profiles werefitted with Gauss normal distribution func-tion. A typical spectrum is shown in figure 1.
7000
Fig: 1: 15N NRA spectrum of a 1000 A thick Cu layeron H terminated crystalline silicon and Gaussianfitting curve
In the case of target materials, as e.g. Nb,which incorporate H easily, the layers were Hcharged using an Ar:H2 3.5 at.% mixture un-der normal pressure. The samples wereheated up to a temperature of about 160°Cwithout exposing them to air to avoid surfaceoxidation. Here an integrated Gauss functionwas used for fitting, see figure 2.
4000 -
2000
6600 6800Energy [keV]
7000
Fig: 2: 15N NRA spectrum of a 1000 A thick Hcharged Nb layer on crystalline silicon and fittingcurve
The thicknesses were determined by Ruther-ford backscattering spectrometry using the
- 1 4 8 -
JAERI-Review 95-019
energy loss of 2 MeV He ions. The stopping-powers were compared with ZBL data [2](1988 data sheet) for electronic stopping.Nuclear stopping is negligibly small at thisenergy. The experimental straggling datawere compared to Bohr straggling [3] and anempirical formula given by Rud et al. [4].Former experimental data for stopping andstraggling were also taken into account [4,5],
Stopping-power:
Fig. 3 shows the stopping-powers obtained bythis and earlier experiments and the ZBLstopping calculation from the 1988 datasheet. For target elements with Z2 below 20the experimental and calculated stopping-powers agree quite well. For elements withhigher Z2 the data from all experiments showa higher stopping-power of about 7 %. Thenew ZBL stopping-powers (1995 data sheet)have been improved for these target elementsand fit also in this range within about 3 %.(Not shown in the figure).
800
| 6 0 0
Exp. Rud el al.
Exp. Briere et aL
This Exp.
ZBL •
80 100
Fig: 3: Experimental stopping-powers for 15N ions at6.4 MeV for various elements. Sold line is ZBL cal-culation (1988 data sheet), others arc experimentaldata as indicated in the legend
Rud et al. are depicted in figure 4. Obviously,the data points all follow the Bohr curve,which confirms former experimental resultsobtained by Briere et al.. The empirical for-mula given by Rud et al. yields to too highvalues for straggling.
2x10'
"= 1x10*
° 5x10=
1 I ' IA Exp. Rud et al
o Exp. Bricre el al
• Thii Exp.
Bohr theory
after Rud et al
20 40 60 80 100
Fig: 4: Straggling of "N ions in various target ele-ments. Solid line is Bohr straggling, broken line isempirical formula from Rud ct al.. others arc ex-perimental data as indicated in the legend
References:
1. W.A. Lanford, Nucl. Instr. and Meth. B66(1992)65
2. J.F. Ziegler, J.P. Biersack, U. Littmark,The Stopping and Range of Ions in Solids,Vol. 1, Pergamon Press, N.Y. (1985)
3. N. Bohr, Dan. Vidensk. Selsk. Mat. Fys.Medd. 18,8(1948) 1
4. N. Rud, J. Bottiger, P.S. Jensen, Nucl.Instr. and Meth. 151 (1978) 247
5. M.A. Briere, J.P. Biersack, Nucl. Instr.and Meth B64 (1992) 693
Straggling:
The experimental data for straggling, Bohrstraggling and the empirical formula from
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JAERI-Revicw 05-019
6 . 1 0 On-site Analysis of 3lV+ Implantation into SapphireUsing Dual Beam System
Hiroshi NARAMOTO, Yasushi AOKI, Shunya YAMAMOTO,Hidefumi TAKESHITA, Peter GOPPELT-LANGER
Department of Materials DevelopmentJAERI/Takasaki
[Introduction]Sapphire(a-Al2O3) is one of potential
substrates to form the quasi-stable phaseswith new functions because it canaccommodate various kinds of transitionmetals with different charge states. Theintroduction of these elements into thechemically inert sapphire can beaccomplished through the ion implantationtechnique exclusively.
New functions will originate from theelectronic structure associated withimplanted species themselves or combinedsystem with induced defects, and it isneeded to know the microstructuralchange like the lattice location of implantsand damage evolution.
In the present study, the surface-sensitiveanalysis is made on the 5IV-implanted layerusing a RBS/channeling technique. For thispurpose, "Dual Beam Analysis System"has been developed where the on-siteanalysis can be made at low temperaturesby detecting scattered ions and secondaryelectrons.
[Experimentals]250 keV 51V+ ions were implanted 40° off
the surface normal at RT and 36K up to thedose of 3.5xlO16/cm2. The implanted layerwas analyzed without warming-up thesample by employing a RBS/channelingtechnique using 2MeV 4He+ ions from asingle-ended accelerator. The channelinganalysis was made only along <0001> axis
but the detection of backscattered particleswas made at 135° and 160°.
[Results and discussion]In fig. 1 an experimental arrangement is
illustrated for dual beam analysis system.In this system, three kinds of energy beamsare available for materials processing andanalysis. Various kinds of ions from 400kV ion implanter are used for surfacemodification, and the modified surface canbe processed using a YAG laser. The ionbeam analysis on the surface region is madealternatively after ion implantation or laserprocessing using 2MeV 4He+ ions from asingle-ended accelerator. In this kind ofstudy the sample temperature will play animportant role and a 6 axis goniometer wasdeveloped which can be operated even inthe low temperature range of 3OK-3OOK.Possible research programs are depictedalso in this figure, and the present study isinvolved in the 2nd research itemof "Synthesis of quasi-stable materialsthrough processing at low temperatures"
In Fig. 2, are shown <0001> alignedspectra with the random one in CX-AI2O3implanted with5IV4" ions at RT using a dualbeam analysis system. The implanted dosewas changed in the wide range of 1014 to3.5xl016 /cm2 to detect the damage growthand the corresponding distribution ofimplanted S1V atoms. In the course ofimplantation, the surface peak is enhancedand the defect profiles change in its
- 1 5 0 -
JAERI-Review 95-019
feature. The peak positions of the defectprofiles go into deeper with the increase ofimplantation dose, and in final the peakposition coincides with that in theimplanted profile of 51V. These changeshave been confirmed only through a dualbeam analysis system because the smallchanges of the damage profiles in differentsamples are not so confident. The presentresults can be tentatively explained by thedifferent interaction of incident ions withthe radiation-induced defects with thedifferent natures. The angular scanningaround <0001> axis, not shown forsimplicity, gives us a conclusion that somepart of implanted 51V+ atoms occupiesAl-sublattice with the introduction oflattice distortion in O-sublattice. Thedistortion in Al-sublattice can not bedetected within the experimental error.
Fig. 3 shows the same kind of analysis at36K as in the previous one. In this case, theimplanted doses was changed in a smallrange of 0 to 1.2xlO15/cm2, and the
implanted profiles of 51V atoms can notbe observed clearly. But in the alignedspectra one can see the huge growth ofdamage in Al-sublattice, and after the doseof7xl014/cnr the implanted layer becomesamorphous judging from the coincidencebetween the scattered yields in <0001>alinged and random spectrum. In the initialstage of the damage growth the profiles arenot symmetric and have a long tail to thesurface but after the amorphization theprofiles become symmetric. The peakposition is fairly shallower compared withthat in RT-implanted sample. In this figure,any enhancement of surface peaks can notbe observed different from the spectra atRT, which indicates the defect recovery isnot so dominant in this temperature range.The peak position is rather close to that atthe initial stage in RT implantation. Furtherstudies will be needed to make clear thedefects responsible for these kinds of ionscattering spectra.
Research Programs*Analysis of electronic state and atomic
arrangement associated with phase transitionnear surface surface region.
*Synthesis of quasi-stable materials throughprocessing at low temperatures
*Ion mixing process in immiscible systems*Radiation effects on low m.p. materials
System
I Collimated Beam
2MeV 4He + from Single Ended Ace.
Fig. 1: Experimental arrangement in"Dual Beam Analysis System"
Two ion beams for implantationand analysis, and a laser beamfor rapid heat treatment areavailable. 6 axis goniometer canbe operated at low temperatures.
- 1 5 1 -
JAERI-Rcview 95-019
2000
1000
keV "V — (0001) a-AI2O3(RT)
1.5Energy [MeV]
Fig. 2: On-site analysis of a-Al2O3 when 250 keV 51V+ implatation at RT using "DualBeam Analysis System". 2MeV 4He+ RBS/channeling is employed. Except arandom spectrum, others are taken under the <0001> aligned condition.
2000 -
1000
• ii-yi , . . .
\
i \m* i
' 1 '250 keV
2.0 MeV
nrtJU. kL
i/
i i i 1 ' '51V —(0001) a - A12O3( 36 K)4He 6=135
0 random1.2 x 1O1S
9.8 x 10M
7.8 x 1014
5.8 x 1014
3.8 x 1014
m 1.8 x 1014
/cm2
/cm2
/cm2
/cm2
/cm2
/cm2
M 8 x 1013 /cm2 Jfl 0 <0001>
. . 1 i .
0.5Energy [MeV]
1.5
Fig. 3: The same kind of ion beam analysis as in Fig.2 but made at 36 K. The dose rangeemployed here is less than 1.2xlO15/cm2.
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JAERl-Rcvicw 95-019
6 . 1 1 Ion Beam Analysis of Diamond Crystal Implantedwith 400 keV 39K+ Ions
Dorothee RUECK*, Mingle GAN, Shunya YAMAMOTOYasushi AOKI, Peter GOPPELT-LANGER
Hidefumi TAKESHITA, Hiroshi NARAMOTO
*GSI-Darmstadt, GermanyDepartment of Materials Development
JAERI/Takasaki
[Introduction]Artificially grown diamonds have shown
to have good crystal perfection and highpurity, and they are ready to be modifiedfor the introduction of new functions. Ionimplantation is a violent technique but it isstill thought to be effective on themodification of physically and chemicallyinert materials like diamonds.
Recently several studies have been madeon the ion-induced damage structure byemploying crystallographic analysis[l] andEPR analysis[2], and the bonding naturesassociated with ion irradiation have beenstudied using Raman technique[3,4].
In the present study, ion beam analysis onK-implanted diamond is shown as the firststep of pursuing a possibility of newcompound formation by the introductionof alkali atoms into carbon-basedmaterials.
[Experimentals]400 keV 39K+ ions were implanted into
(001) diamond single crystal at ambienttemperature under a random condition.The ion beam intensity was kept as high aspossible expecting enhanced reactionsbetween carbon atoms- in substrate andimplanted 39K atoms. The size of beam spotwas 1 cm2 and the typical intensity was 2-4(iA/cm2. Samples with two different
doses(5.0xl015/cm2 and 2.6xlOI6/cm2)were prepared for the damage structureanalysis and also for the analysis of K-Cinteractions, respectively.
The implanted surface layer of diamondwas analyzed by using RBS/channeling of2MeV 4He+ ions. During the analysis,special attention was paid to avoid thenoises from discharging.
[Results and discussion]In fig. 1 typical RBS/channeling spectra
are shown in <001> diamond crystalimplanted with 400 keV 39Kf up to 5.0xlO'Vcm2. The <001> aligned spectrumfrom the unimplanted region is alsoshown . A curve depicted by a solid linecorresponds to a spectrum taken under arandom-orientation equivalent condition.The <001> aligned spectrum afterimplantation is shown in a dashed line. Inthis figure one can recognize the sameintensity in the random and alignedspectrum after implantation, whichindicates the formation of an amorphouslayer after this low dose implantation of5xlO15/cm2 39K+ ions even at ambienttemperature . In the intensity profiles fromimplanted 39K+ ions there is no difference,which suggests no substitutionaloccupation of implanted ions in thesubstrate crystal lattice. The implanted
- 1 5 3 -
JAERl-Review 95-019
profile seems asymmetric, different fromthe standard feature of implanted species.The implanted atoms distribution isbroadened to the surface, which can berather explained by atomic diffusion to thesurface and not by compound formation,because one can not see any step at theleading edge of the diamond surface. Also,there is no evidence of oxidation of 39Katoms moved to the surface.
After the implantation of 2.6xlO16/cm2,which is about 5 times higher compared tothe previous case, the profile of implanted39K atoms has become more pronouncedand more symmetric, which can be seen inFig. 2. But the width in the amorphousregion of the diamond substrate is almostconstant. These results cannot beexplained in a simple manner but it can betentatively attributed to the K-compoundformation. The compound formationassociated with implantation might notinduce a long range migration of implantedspecies.
In the forthcoming study, the surfacelayer will be analyzed using a Ramanspectrometer after annealing at severaltemperatures far below the oxidation one.The deep ion implantation is also expectedto keep the surface layer crystalline. Underthis condition the amorphized layer canreceive an internal high pressure withoutany influence of getting oxygen, whichmight induce the different kinds ofcompounds far from the standard.
References1)S. M. Gorbatkin, R. A. Zuhr, J. Roth and
H. Naramoto, J. Appl. Phys.70(1991)2986.
2)J. Isoya, H. Kanda and Y. Morita, 4thInter. Conf. on New Diamond Scienceand Technology(Kobe, 1994).
3)S. Sato, H. Watanabe, K. Takahashi, Y.Abe and M. Iwaki, Nucl. Instr. Meth.B59/60(1991)1391.
4)E. H. Lee, D. M. Hembree, Jr., G. R. Raoand L. K. Mansur, Phys. Rev.B48(1993)1540.
2.0 MeV 4He* on Diamond
Imp!, with 400 keV 39K .
(5.0 x 1015 /cm2)
0.5 1Energy [MeV]
Fig. 1: RBS/channeling spectra in diamondimplanted with 400 keV 39K+ ions upto 5.0xl015/cm2. Aligned spectra weretaken along <001> axis.
800
2.0 MeV 4He+ on Diamond-39Impl. with 400 keV 39K _
(2.6 x 1016 /cm2)
0.5 1Energy [MeV]
Fig. 2: RBS/channeling spectra in diamondimplanted with 400 keV 39K+ ions upto 2.6xlO16/cm2. Aligned spectrawere taken along <001> axis.
- 1 5 4 -
JAERI-Review 95-019
6 . 1 2 Analysis of Hydrogen in Nb/Cu Multilayers Using Ion Beams
S.Yamamoto, P.Goppelt-Langer, Y.Aoki, H.Takeshita, H.NaramotoDepartment of Materials Development, JAERI/Takasaki
Introduction
In metallic multilayers composed oftransition elements like those of the Vagroup of the periodic table, hydrogen atomsare reasonably expected to play an importantrole for relaxation of interface lattice strain.H is easy to diffuse and to accommodate inthe matrix lattice interstitally up to a certainlevel or the form of hydrides. Thus it isneeded to analyze the structure referring tothe matrix elements and hydrogen atoms.These kinds of analyses can be performed byusing the binary interaction process of ionswith the atoms in solids.
In the present report, Nb/Cu layer systemare prepared for the above purpose usingevaporation technique under UHVcondition. Ion beam analysis based on elasticscattering and resonant nuclear reactions ofMeV ions is employed which gives thedepth-dependent information of the relevantelements with satisfying depth resolution.
Experiment
Nb/Cu multilayer samples were preparedon 0C-AI2O3 substrates at ambienttemperature using the electron beamevaporation technique under UHVcondition. During evaporation, the vacuumin the growth chamber was kept to beconstant after a long term evaporation of Nbso that the gettering of hydrogen bydeposited Nb on a chamber wall can beoperative. The thickness of each layer wasmonitored with quartz oscillators. Thesamples were transferred to an introductionchamber after the growth, and the hydrogenwas introduced under Ar(H2) mixtures at
150°C without exposing sample to open air.The hydrogen analysis was made undervacuum after taking out samples to open air,and it can be assumed that the hydrogen is inbalance within the deposited layers.
The layered region was analyzed usingtwo kinds of ion beams from 3 MV tandemaccelerator at TIARA facility inJAERI/Takasaki. The thickness of Nb andCu layers of the multilayer were determinedby heavy ion Rutherford backscatteringspectrometry(HI-RBS) using 16 MeV I6O5+
ions[l]. The size of 16O5" ions beam wasabout 0.6 mm in diameter and the beamcurrent was about 10 nA typically.Backsacttered particles were detected by astandard surface barrier detector placed 11cm from the sample at 170°. Also the highenergy elastic recoil detection using 16 MeV16O3+ ion was useful to survey the hydrogendistribution roughly.
The hydrogen profiling of Nb/Cumultilayers were accomplished by employing'H(l:)N,aY)12C resonant nuclearreactions(15N-NRA)[2]. The present nuclearreactions have a narrow resonance withwidth of about 2 keV at 6.385 MeV[3]. Thecharacteristic y-rays of 1H(15N,ay)12Cnuclear reaction were measured as a functionof the incident ion energy with 3" Nal(Tl)detector[3]. Data points were taken in stepsof 10 to 20 keV. To avoid the loss ofhydrogen during the ion beam analysis, themeasurements were made with increasingand decreasing incident energy of 15N ions.
Results and Discussion
Fig.l shows a typical HI-RBS spectrumfrom a Nb/Cu multilayer on OC-AI2O3
- 155 -
JAERl-Rcview 95-019
2
800
600
400
200
n
l ' '
Cii
1
1 ' '
40 nm*
h 1
\ 11. W . .
Nb
30
r
i
-nm
20 nm .
10 nm
Energy [MeV)
Fig.l HI-RBS spectra of Nb/Cu multilayersample.
16,substrate using 16 MeV 0 ions. In thehigher energyregion one can see four wellseparated peaks coming from Nb layers withthicknesses of 10,20,30 and 40 nm in thisorder from the surface. The peaks in thelower energy region are attributed to thecorresponding 20 nm Cu layers insertedbetween Nb layers. In the Cu peaks, thereappears a complicated structure which iscaused by the contributions of Cu isotopes.This demonstrates also good mass-resolutionof HI-RBS. In the analysis of multilayeredstructures with many layers, this kind ofanalytical technique will become moreimportant in the near future. The depthresolution in this method is better (10 nmFWHM) and a further improvement can beaccomplished by tilting a sample(3 nmFWHM).
After the preparation of Nb/Cu multilayerfilm as in Fig.l, was introduced. Fig.2 showsthe results of hydrogen profiling in thosesamples by employing the resonant nuclearresonant reactions, ^ (^N .ay^C . Thedetermination of the absolute hydrogenconcentration was made by referring to ahydrogenated amorphous Si (with 14 at.%H) on a Si crystal. The sharp peaking around6.40 MeV is from adsorbed water at thesurface. The shape of the hydrogendistribution corresponds well to the depthdistribution of Nb, which implies thelocalization of hydrogen atoms in the Nb
6.6 6.8 7Energy [MeV]
Fig.2 H concentration of Nb/Cu multilayerusing 15N-NRA.
layers.Fig. 3 shows the dependence of hydrogen
concentration on the Nb layer thickness fortwo kinds of samples, low-charge and high-charge ones. In the low-charged samples,there is not any thickness dependence on thehydrogen concentration but in the high-charged samples are recognized a linearincrease with Nb layer thickness followed bya saturation behavior. In the low-chargedsamples, the concentration of hydrogenatoms is at the maximum as species whichoccupy the interstitial positions. In the high-charged samples, the hydrogen concentrationat thick layers goes beyond the a-phase limit.These are assumed to be mixed statebetween a-and P-phases. In thinNblayers the transformation into a- orP-
^ 2 0 -
co
sca
s
10 -
-
1 1
1
•\ •••••-...
•p.
*-•
.••
,•• pP o *
/ 0"'
. 1 ,
1
..,.o
1
,o
••'• .."»".".::»"»6 " ' '
1 . i .
i • '
o
° °
1 . 1
1 .
-
-
-
o
;
20 40Nb thickness [nm]
60.
Fig.3 H concentration dependence on Nblayer thickness.
- 156 -
JAERl-Review 95-019
phases, or both can not be caused easilybecause the both sides are constrained by Culayers.
In this report it was shown that acombined ion beam technique like l3N-NRAand HI-RBS was useful to obtain the depth-sensitive information about introducedhydrogen and substrate atoms bydistinguishing the contributions from all therelevant elements.
References
[1] P. Goppelt-Langer, S.Yamamoto,Y.Aoki, H.Takeshita, H.Naramoto,TIARA Report 1993.
[2] S.Yamamoto, P.Goppelt-Langer,Y.Aoki, H.Takeshita,H.NaramotoJIARA Report 1993.
[3] W.A. Lanford, Nucl. Instr. and Meth.B66( 1992)62.
- 1 5 7 -
JAERI-Review 95-019
6 . 1 3 Depth Distribution Analysis of Hydrogen and Deuterium in Nickelby ERDA
T.Mitamura, M.Terasawa, K.Arashi, L.Liu,
S Yamamoto*, P.G.Langer*, H.Takeshita*, Y.Aoki* and H.Naramoto*Department of Engineering, Himeji Institute of Technology
* Takasaki Radiation Chemistry Research Establishment, JAERI
1. Introduction
Hydrogen atom in nuclear reactor materials
plays an important role in the radiation
damage evolution via the embrittlement of
structural and pressure vessel alloys and the
formation of metal hydrides. As hydrogen
atom is a comparatively simple prototype of
reactive interstitial solutes in metals, it
provides information of basic processes and
properties of interactions between radiation
damages and solutes.
In the present study, depth distributions of
hydrogen and deuterium in polycrystalline
nickel which deuterium or helium ions were
implanted or irradiated, were analyzed by the
elastic recoil detection analysis (ERDA)
method.
2. Experimental
Polycrystalline nickel (99.7%) were cut
into specimens in the size of 1.0 cm x 1.0
cm x 0.02cm. The surface of the specimens
were polished by electrolysis method.
Deuterium ions or helium ions were
bombarded to the specimens. The energies
of deuterium and helium ions were selected
on the basis of calculations with a computer
simulation code, TRIM91. Two types of the
specimens were prepared; specimens
implanted only with deuterium ion and
specimens implanted with deuterium ions
after helium ion irradiation. Ion fluence were
varied in the range of 0.5 ~ 3 x 10!6cm'2
During ion irradiation, specimens were seton a water-cooled target stage. Depthdistribution of helium and deuterium wereanalyzed by ERDA using 16 MeV O16+ ionsas a probe, which were accelerated by aTandem accelerator of Japan Atomic EnergyResearch Institute (JAERI). The incidentangle of the oxygen ion beam was 15 degreeto the surface of the specimens and recoiledparticles were detected at 30 degree by acharged-particle detector placed at 30 cmapart from the target. The detector waspreceded by a slit with 1 mm width and aPET absorber with the thickness of 25 |J.m.The beam intensity was about 24 nAand thetypical beam area was 1 mm in diameter.
3. Results and discussions
In Figure 1, an ERDA spectrum obtained
with a specimen implanted only with 35
keV/amu deuterium ions with the fluence of
3 x 1017/cm2 is shown. Figure 2 shows a
spectrum obtained with a specimen irradiated
with 70 keV/amu 3He ions with the fluence
of 3 x 1017/cm2 following 70 keV/amu
deuterium ion implantation with the fluence
of 3 x 10I7/cm2. In the both figures, are also
shown the calculated distributions of defects
and ions for comparison.
In the Fig. 1, the deuterium ion distribution
observed at about 0.7 Jim is much shallower
- 1 5 8 -
JAERl-Review 95-019
and narrower, compared with the results bythe 1RIM91 calculation. A significantamount of deuteriums at the surface are alsoobserved. The hydrogen atom distribution isnot flat It shows the peak at 0.24 p.m,which is deeper than the peak of damagedistribution introduced during deuteriumimplantation. In Fig. 2, the observeddeuterium distribution is nearly coincidencewith the calculation of damage distribution.Similar results were observed in the otherspecimens with different ion fluences.
In the present study, it was shown thatdeuterium ions are more mobile at roomtemperature in helium-non-implanted nickelthan in the helium-implanted nickel.Provided that the introduced defects werenot so diffusive at room temperature,radiation defects is only a weak trapping sitefor the deuterium atom. The observed peaksof hydrogen and deuterium atoms in Fig. 1are probably understood as a result ofdiffusion without defect trapping. Althoughthe peaks suggest that the radiation defectsmay have some effects of trapping ofhydrogen and deuterium atoms, the effectsare not so remarkable because thedistribution peaks observed are not incoincidence with TRIM code calculation.The surface of the specimen seems toprovide rather preferable trapping site for thedeuterium atoms.
In helium implanted nickel, the deuteriumdistribution shows similar coincidence withdamage distribution introduced by heliumirradiation. It has been reported that heliumbubbles is a strong trapping site for thedeuterium atom^. The void-like character ofhelium bubbles seems to contribute totrapping the deuterium, and the trapped
deuterium atom might be retained at roomtemperature. The deuterium depthdistribution spectrum observed in thepresent study confirms this effect. Furtheranalysis is under proceeding.
3SkeV D ion, 3x10 /cm2 to Ni
'0.3Depth ((I)
Fig. 1 ERDA spectrum obtained from a
nickel polycrystal specimen implanted with 35
keV/amu deuterium ions with a fluence of 3 x
1017/cm2. Thin and thick lines ate ion and
damage distribution calculated by TRIM91,
respectively.
70keV 'He 3x10''/cm2
+ 70keV D 5x10' '/cm'to Ni
'0.2 0 . 3 ' 0 . 4Depth 00
2 100.6(H)0.7(D)
Fig. 2 ERDA spectrum obtained from nickel
polycrystal specimen implanted by 70 keV/amu
deuterium ions with a fluence of 5 x 1016/cm2
after 70 keV 3He ion irradiation with a fluence
of3xl017/cm2.
Referencesl)F.Besenbacher, J.bottiger and S.M.Myers,J. Appl.Phys. 53(1982)3547
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JAERI-Review 95-019
6 . 1 4 Nuclear reaction analysis of carbon in C-ion irradiatedGaAs
K. KURIYAMA.T KATO. K. SAKAI. S. YAMAMOTO*?Y. AOK1*.H. TAKESHITA* and H. NARAMOTO*College of Engineering and Research Center of Ion BeamTechnology, Hosei University, and* Department of Materials Development, JAERI
Introduction
Carbon is a promising p-type dopant in GaAsbased devices such as heterojunction bipolartransistors mainly because of its low atomicdiffusivity in GaAs. High dopingconcentrations can be obtained by low-pressure metalorganic chemical vapordeposition (MOCVD)[1J and ion-implantation[2,3|. In C-ion implantedsamples[2j, however, doping efficienciesgenerally ranged only from 2 to 8 %, which ismuch lower than those of more conventionalp-type implants such as Zn or Cd(approximately 100 % p-type activity can beachieved in Zn- or Cd-implanted GaAs forimplantation doses of < 1014 cm-2 after 800 to900 °C anneal). Therefore, the distribution ofcarbon atoms in C-ion irradiated samples isimportant for an evaluation of the low dopingefficiencies after annealing. Nuclear reactionanalysis (NRA) was used to obtain theinformation of the carbon atoms in the C-ionirradiated samples.
Experiment
Materials used in this study were undoped(lOO)-oriented semi-insulating GaAs grownby the Czochralski (PCZ) method. Thesematerials were n-type and contained EL2defects at a concentration of ~1016 cm-3. 700KeV 12C-ions were irradiated at about 300 Kusing the 3MV-Tandem accelerator at HoseiUniversity. The carbon dose was 5 xlO16 cm2
which is a suitable dose to make a distinctionbetween the irradiated C and the surfacecontamination of C. Rutherford backscatteringspectrometry (RBS) methods are not sensitive
to impurities with low atomic number, such ascarbon, because the backscattered yield fromsuch impurities is small, and it overlaps withthe larger signals from the Ga and As in thesubstrate. Consequently, NRA was employedin this study using the l2C(d, p)13C reactionsince the high energy product, a 3.1 MeVproton, can be detected without interferencewith the Ga and As signals. For the NRAmeasurements, a beam of 1.3-MeV deuteriumions with a current of ~3 nA, a net deuteriumdose of 1014 enr2 and a diameter of ~1 mmwas used. The NRA experiments wereperformed using the 3MV-Tandem acceleratorat JAERI. In the NRA system a Mylar film of
thickness of ~7 um was located in front ofthe proton detector to reduce the pile-upcaused by the backscattered deuterium ions.
Results and discussion
The spectrum for 1.3-MeV deutrium beamincident along the <100> channel and atrandom direction after C-ion irradiation showsthe variation of RBS yield ranging from the
surface to about 1 um (see Fig. 1), but noamorhous layer was formed by the C-ionirradiation. In a 600 °C annealed sample, thealingned yield in the irradiated layer except forthe surface region was slightly lower as thatof as-irradiated sample, indicating the partialrecovery of the crystallinity due to annealing.
Figure 2 shows the nuclear reaction yield asa function of channel number obtained fromthe C-irradiated GaAs with the ion beamaligned [ 100] direction. The net yield of therandom carbon signal is proportional to the
- 160
JAERI-Rcview 95-019
C:5x1015cnr2
as-lmplanlcd600°C anneal
random
150 250 350
CHANNEL NUMBER450
Fig.l Backscattering <100> aligned and random
spectra for 5 x 1016 cm"2 C-ion irradiated GaAsusing 1.3 MeV D* ions as an incident beam.
300
= 200
ou>
100
C:5x10'6cm2
as-Implanted
150*
aligned to [100]random
400 450 500CHANNEL NUMBER
550
Fig.2 Nuclear reaction yield as a function ofenergy ( shown as channel number) obtainedfor an as-irradiated sample (5 x 1016cm"2 C)using 1.3 MeV D+ ions as an incident l>eam.
total carbon concentration, which channelnumbers correspond to smaller depth belowthe sample surface. The aligned spectrum ofthe as-irradiated sample is identical to therandom spectrum, indicating that the irradiatedcarbon ions are located in random lattice sites.
In a 400°C annealed sample (see Fig.3),the nuclear reaction yield separates clearly twopeaks. This is due to the reconstruction ofcarbon atoms in the irradiated layer.Furthermore, the spectra of the NRA shift tothe surface in comparison with those of theas-irradiated sample, indicating the migrationof the carbon atoms toward the surface. Therandom spectrum observed here is similar tothe NRA measured in MOCVD C-dopedepilayers[4]. The irradiated carbon, therefore,is distributed homogeneously in the irradiatedlayer. However, we can see an importantdifference between the random and alignedspectra. In comparison between the alignedand random yields, the aligned yield near theinterface between the irradiated layer and thesubstrate decreases, indicating that theirradiated carbon near the interface is locatedat substitutional sites. On the other hand, thealigned yields between channels ~475and -485 increase in comparison with thoseof the random yields. This suggest that a partof the carbon atoms in this region is located at
interstitial lattice sites. In the surface region,the lattice location of the carbon atoms werenot changed by annealing.
In a 600°C annealed sample, the alignedand random spectra of NRA are similar tothose of the 400°C annealed sample (seeFig.4). The carbon atoms also show a slight
c3
Q
UJ
300
200
100
C: 5x1016 cm-a400°C annealed
aligned to [100]random
400 450 500
CHANNEL NUMBER550
Fig.3 Nuclear reaction yield as a function ofenergy (shown as channel number) obtainedfor a 400QC annealed sample (5 x 1016cnr2 C)using 1.3 MeV D+ ions as an incident beam.
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JAERl-Review 95-019
300
200
100
C: 5x101">cnvJ
600°C annealaligned to [100]random
1.3MeV D
NRA
400 450 500CHANNEL NUMBER
550
Fig.4 Nuclear reaction yield as a function ofenergy (shown as channel number) obtained fora 600 °C annealed sample (5 x 1016cnr2 C)using 1.3 MeV D+ ions as an incident beam.
shift toward the surface. Furthermore, theNRA yields near channel 500 decrease incomparison with those of the 400°C annealed
sample, suggesting carbon migration from thesurface region. The aligned yields fromchannels -480 to -490 are also beyond therandom yields. It is suggested that theinterstitial fraction of carbon atoms increasesin tills region and the accumulated layer ofcarbon such as clusters may be formed.
Further studies of NRA measurements inthe C-ion irradiated GaAs are required for theestablishment of the movement of carbonatoms due to the annealing and theconfirmation of the reproducibly of the NRAdata.
References
[1J G.E.HSfler, H.J.HSfler, N.Holonyak,Jr.and K.C.Heieh, J. Appl. Phys.72, 5318(1992).
[2] B.K.Shin, Appl. Phys. Lett. 2 9, 438(1976).
[3] W.H.van Berlo, J. Appl. Phys. 7 3, 2765(1993).
[41 G.E.Hofler. and K.C.Hsieh, Appl. Phys.Lett. 61,327(1992).
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JAERI-Review 95-019
6 . 1 5 Study on Mineral Alteration-Analysis of Initial Stages of Hydrothermal Alteration-
Toshihiko OHNUKI, Tsutomu SATO, Hiroshi ISOBE.Shun-ya YAMAMOTO*, P. Goppelt-Langer*, Yasushi AOKI*.Hiroshi NARAMOTO* and Takashi MURAKAMI**
Department of Environmental Safety Research, JAERI,* Department of, JAERI,**Faculty of Science, University of Tokyo
Introduction shape of secondary minerals and constituentsMigration of radionuclides through geological of solution.media must be studied to estimate the impact Experimentalof radioactive waste disposal. Radionuclides
are sorbed on minerals and/or clay minerals in The mineral used was single crystal of albitegeological media during the migration, so that (NaAlSi3O3). A albite was contacted with 9
sorption studies have been carried out by many ml of the 0.01 M CH3COOU solution in tefron
research scientists. Minerals and clay minerals tube, subsequently the suspension was heated
are altered to secondary minerals by water-rock for between 3 and 150 days at 90 - 210°C under
interactions. This suggests that the sorption a vapor pressure of the solution. The solid to
characteristics of radionuclides on the surface solution ratio was prepared to be 1 (cm2): 30of minerals and clay minerals may be changed (ml).during the alteration processes. The minerals occurred were examined by X-
Feldspar, one of the minerals contained in ray diffraction analysis (XRD). The shape of
granite which is the candidate for the host rock the surface of the altered product and the
of high level waste disposal repositry, is easy occurred minerals were observed by scanning
to react with groundwater, and alters to form electron microscopy (SEM). The elements
secondary minerals. Thus, change in sorption contained in thethe atered product and the depth
characteristics feldspar during alteration should profile of concentration of Na and Si were
be clarified. determined by energy dispersive X-rayThe study on the alteration of feldspar is not analysis (EDX). Depth profiles of hydrogen
a new field. But it has been just the last twenty from the surface was measured by resonantyears that directly study on minerals surfaces, nuclear reaction analysis (RNRA), in which y
fluids near surfaces, and the solid-fluid interface ray generated in the nuclear reaction of ' H ^ N ,
have been developed. In this report, ay)12C was detected,hydrothermal experiments of albite, one of the pH and the concentrations of the dissolved
end menbers of feldspar, have been carried out, Na, Al and Si were measured by inductively
then the dissolution process, mechanism and coupled plasma atomic emission spectroscopyrates of alteration of albite has been examined (ICPAES).based on the observed minerals on surface,
- 163 -
JAERI-Revicw 95-019
Results and discussion obtained at 150°C for 7 days.The concentrations of Na and Si in the
pH of the solution was kept at 4.56 during the solution were plotted at the gibbsite or boehmitehydrothermal experiments. SEM observations region in the activity diagram. The Na/Sishow that etch pits appeared on the surface of concentration ratio in the solution was high atthe reactant obtained at both 150 and 210°C. the initial stage of dissolution of albite, thenThe width and depth in the etch pits increased decreased to 1/3 with time. The concentrationwith time. And more than three different of Al was very low. This is caused by formationalminium minrerals ( 0.2 - 1 |im in size) were of the alminium containing secondary mineralsoccured. While any etch pit was observed on at the surface of the altered product,the reactant obtained at 90°C. These results show that the ion-exchange
The depth profile of Na/Si ratio near surface reaction of H+ for Na+ in albite are dominant atregion of the altered product obtained by SEM- the initial stage of the alteration, and thenEDX (Fig. 1) indicatse that Na/Si ratio was less congruent dissolution which starts at dislocatedthan 1/3 at the surface of the altered product region is dominated,obtained at 150°C for 3 days. And Na/Si ratio u"decreased with time, then reached to 0.2 after 035
90 days. The position where Na/Si ratio wasless than 1/3 was proceeded to deeper directions °-3
with time. For instance the position wheresra 0.25
Na/Si ratio was 0.3 was shifted from 0 for 3
day to 3 }im for 90 days. By the RNRA, 0.2
enrichment of hydrogen was not observed in the
altered product obtained at 90 °C for 7 days (Fig. °'15
2). And the enrichment of hydrogen was
observed until 1 Jim in the altered product
. ' ' '
9A
v™
JB..
H
. . .
A !
. . .
A A| * . •
r ' •
,a •
,
' ' '
D
0 3 dayA 30 daysB 90 days
I
• -
4 6
Depth jftip
10
Fig. 1 Depth profiles of Na/Si ratio
800 -••
8
600
400
200
- . . ' • •
C)
&
. A
,8«anf
• .
A
i i i
© 90°C3days i '•O 90°C 7 days 1 -• 150°C3days 1^ 150°C7days |
Q . R
•
*
200 400 600Depth (nm)
800 1000
Fig. 2 Depth profiles of hydrogen by RNRA
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JAERI-Review 95-019
6 . 1 6 Ion Beams Irradiation Experiments Combined withPositron Spectroscopy
Sohei Okada, Masayuki Hasegawa*, Atsuo Kawasuso, Shin-ichi Masuno,Makoto Tabata* and Masashi Suezawa*Advanced Radiation Technology Center, JAERIinstitute for Materials Research, Tohoku University
Introduction
We have performed three sorts of ionbeams irradiation experiments combined withpositron spectroscopy:1) internal positron source technique,2) slow positron source production,3) ion-induced defect analysis with a slow
positron beam.Substantial experiments have just started aftera recent permission of the authorities for theuse of positron emitters. Here are reportedsome results of the preliminary studies.
Internal positron source technique
It is possible to produce a positron emitter22Na inside silicon from a nuclear reaction28Si(p,7Be)22Na with a proton bombard-ment. This internal positron source enablesthermal defect studies by using positronlifetime measurement at high temperaturewhere usual positron sources would be meltdown.
In Fig.l are shown positron lifetimespectra of a high-purity FZ-silicon irradiatedby 70 MeV proton from the TIARA AVFcyclotron. The fluence was 2.5 X 10i7cm-2.The lifetime measurement was carried out atroom temperature. The spectrum (a) is for thesample as irradiated. It is resolved into threecomponents: r ! = 170ps(/i=59.4%), r 2=
284ps(/2=39.0%) and X 3=1.73ns(/3=1.6%),where T and / are the lifetime and theintensity, respectively. The value of r 3 istoo large for that corresponding to defects insilicon. When the irradiated specimen wassandwiched between two unirradiated ones,
this component disappeared as shown in thespectrum (b). Consequently, this smallamount of extra component is assumed tocome from positrons emitted from the vicinityof the surface of the irradiated specimen intoair and/or surrounding materials like adetector. This is an important fact which wemust pay attention in use of the internalpositron source technique.
The value of r 2 indicates that the vacancyclusters were induced by the irradiation,which survive even at room temperature. Wewill further investigate the detail of theclusters with elevating the temperature andalso the behavior of thermal defects at muchhigher temperatures.
iou
,-2•S 10'
a io"3
5 TO"4
10',-5
100 200 300 400Channel Number
Fig.l Positron lifetime spectra of a high-purityFZ silicon irradiated by 70 MeV proton,which were measured by using theinternal positron source technique.
Slow positron source production
It was calculated with the IRAC code that a8/iA"h bombardment of 70 MeV protononto an iron target produces a positron emitter
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56Co of more than 90MBq in activity insidethe target by a nuclear reaction 56Fe(p,n)56Co. Since iron has a negative surface workfunction for positrons, it is expected that apart of thermalized positrons inside the targetare emitted from the surface as slow-positrons. Therefore, the proton irradiationhas a possibility to produce a slow positronsource, where the target itself works as apositron moderator.
We have confirmed by a preliminaryexperiment with a reduced proton currentusing small test pieces that the positronemitter of an amount coinciding with thecalculation will be available. We also tried the70 MeV proton irradiation onto a honeycomb-shaped iron target of 20(W)X35(H)X25(D)mm in size, which has a wide surface area forthe slow positron emission. It was found thatthe proton current was limited to be up to 200nA when a single side cooling by water wasapplied. We will investigate the coolingtechnique and try to detect slow positronsfrom the target in future works.
Ion-induced defect analysis with a slowpositron beam
It is important to analyze defect formationalong an ion beam path in application of MeVion implantation. Doppler broadeningmeasurement using a slow positron beam isone of the powerful means for the analysis.
We tried the depth profiling of vacancies ina silicon single crystal induced by 1 MeV O1+
implantation, by using the TIARA 3MVTandem accelerator and a slow positron beamin Tokai laboratory. The amount of the ionwas 1015, and the irradiation area was 5mm
X 5mm. The result is shown in Fig.2. The S-parameter increases with the positroninjection energy, which indicates thatvacancy-type defects were produced along theion beam path. However, a quantitative depthprofiling was not successful because thepositron beam of more than 9 keV, whose
beam size was about 5mm 4>, deviated from
the irradiation area.We have been engaged in constructing a
stable slow positron beam. The positronsource was received at the end of March in1995. We will restart the defect study after arenewal of the shielding part.
0.525 10 15
Positron Injection Energy (keV)
Fig.2 S-parameters of annihilation radiationfor a silicon irradiated by 1 MeV oxygenion beam.
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JAERI-Revicw 95-019
6 . 1 7 Observation of the initial stage of laser ablation
A.Miyashita, T.Ohyanagi*, O.Yoda and K.Murakami*Department of Materials Development, JAERI Takasaki•institute of Materials Science, University of Tsukuba
The laser ablation is recognized to be wellsuited for formation of new materials such ascarbon clusters12'. It is important tounderstand the mechanism of clusterformation. We have investigated propertiesof the initial stage of laser ablated carbonparticles with limc-rcsolvcd X-rayabsorption spectroscopy using laserproduced plasma X-rays (LPX) as an X-raysource.
Figure 1 shows a schematic drawing ofour spectrometer. A 20.1 Q-switchcdNd:YAG/glass laser which is frequency-doubled with the use of a second harmonicsgenerator (SHG) is used to generate soft X-rays. The power of X-ray generation laser(wavclcnglh:532nni) per pulse is 7J andFWHM of pulse is 12ns. A part of thefundamental wave is frequency-doubled withanother SHG, and the SHG generates U,532nm sample irradiation laser beam. Thisbeam can be over again frequency-doubledwith a FHG (4-lh harmonics generator), andthe FHG generates lOOmJ, 266nm beam.We also use a 450mJ, Q-switchcd Nd:YAGlaser for sample irradiation. The FWHM ofsample irradiation laser pulse is 8ns. The X-ray probing delay time between sampleirradiation and X-ray source generation laserpulses can be controlled electrically, so wecan observe laser ablation characteristics upto lms after sample irradiation.
The X-ray generation laser beam isfocused on the target at 100|.un in diameter,in this case, irradiancc reaches as high as7x 1012W/em\ and hot and dense plasma onthe target generates soft X-rays. A toroidalmirrors arc used to collect and converge X-rays on the sample. X-ray probe sixc at thesample position is about 0.1mm high and0.5mm wide. The probing X-rays passthrough the ablation plume which is
0.0Z60 270 280 290 300
Energy feV]310
HO.2. X-ray absorption spectra near K-cdgeof the laser ablated carbon particles. Thewavelength of the irradiation laser is 532nm,the energy density is 20J/cm", and theprobing delay time after sample irradiationis 120ns.
sample irradiation laser
Jens
ample chamberX-ray generation laser
Analysis chamber
Target chamber
FIG.l. Schematic drawing of the time-resolved X-ray absorption spectroscopy apparatus.
- 1 6 7 -
JAERl-Review 95-019
generated by laser irradiation. The X-rayprobing position is adjusted by the samplesurface. We have decided the probingposition at which half X-rays are blocked bysample to be 0. In the analysis chamber, agrazing incident flat field grating is used asenergy analyzer. The energy resolutions ofour spectrometer arc 0.8cV and 2.0eV inenergy ranges of 100~200eV and200~500eV, respectively3'.
Figure 2 shows X-ray absorption spectranear K-edge of laser ablated carbon particles.Delay limes between laser irradiation and X-ray probing is 120ns. The spectra exhibitseveral absorption peaks. The absorptionpeaks, 28leV, 284eV, 288eV and 293.5eVarc originated from C" ion, neutral carbonatom (C°), C+ and C2+ ions, respectively"4'.We have measured time and spacedistribution of the laser ablated carbonparticles in order to decide the speed ofablated particles. Figure 3 shows the timedistribution of ablated carbon particles nearthe sample surface. C2+ ions are emitted fromthe sample surface during the laser irradiatesthe sample. On the other hand, lowly ionized(C", C+) and neutral (C°) carbon particles arcemitted from the sample surface even afterlaser irradiation. This suggests that lowlyionized or neutral" carbon is emitted from thesample by the heating effect of the irradiationlaser, and highly ionized carbon is producedby direct laser excitation.
Figure 4 shows the spatial distribution ofthe absoiption peak height originated fromthe ls-»2p transition of ablated carbonparticles. The absorption peak of C2+ ions is
1.0
2 0.8
J10.6
0.4
50.2
0.0
yrf
A—»™ Cz>
......
20 40 60 80Delay Time [ns]
100 120
F1G.3 Time distribution of the ablatedcarbon particles near the sample surface.The laser wavelength is 266nm, energydensity is 5J/cm2, and the probing positionis 0.2mm.
1.0
- ".ac
| 0.6
1 °-4
g 0.2Q.
0.0,0
\
\
XA\ \\
120ns,20J/cm 2
—"O— C—D-. C*— » " C=*••••a— Q;
500 1000 1500Position |pm]
2000 2500
F1G.4 Spatial distribution of the ablation peakheight. The irradiation parameters are thesame as figure 1.
observed more than 2mm from the surface.The C+ ions can be observed more than1.5mm where neutral carbon cannot beobserved any more. The absorption peak ofC" decreases rapidly as the distance from thesample surface increases. Therefore, at theinitial stage of laser ablation, the speed ofC2+ ion is more than 1.8xl06cm/s. Thespeed of neutral carbon is less than1.2xl()6cm/s, and C+ ion has a mediumspeed between former two. These suggestthai acceleration of laser ablated particles iscaused by two effects. One is ahydrodynamic expansion from the samplesurface to vacuum. This effect gives kineticenergies to neutral atoms and ionscquivalcnlly. The other is a Coulombacceleration effect by the transient electricfield made by the irradiation laser. Thiseffect accelerates charged particles inproportion to the ionization level.
The unknown absorption peak, at 286eVis observed close to the sample surface with
0.6
E
co
0.4 -
2-0.2 -o
6 No
\
11
d/
Probing Position
—o— 0.2mm- o -1.0mm --o--3.0mm
^ o ^ - -A- -4.0mm
• < £ - * ' • • • i • • • • I0 500 1000
Delay Time [ns]1500
FIG.5 Time dependence of the ls-»Jt*transition peak height. The wavelength ofthe irradiation laser is 1064nm, and theenergy density is 3.1/cnr.
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JAERI-Review 95-019
1.5
•4J
,•1.0 -
co!0.5
a.coin
•<
0.0
1.5
260 280 300 320Energy [eV]
340
FIG.6 X-ray absorption spectra at 180ns and880ns delay times probing positions are0.2mm and 3mm.
delay limes up to 120ns. This peak is notoriginated from the ls-^2p transition of thesingle atom and ions. With low energydensity of the irradiation laser, it is adominant absorption peak. We observed thispeak at long delay times using twoelectrically synchronized lasers to determinewhether this peak is originated from thesurface localized particles or slow particles.Figure 5 shows the time dependence of theabsorption peak height at 286eV. The peak isobserved even when the probing position isdistant from the surface. This points out thatthe 286cV absorption peak is originated fromslow particles and the mean speed of theparticles is estimated to bc4.8xl0scm/s fromthe delay lime of the absoiption maximum.The speed of the ablation particle is aboutone half of that of the neutral carbon atom.Figure 6 shows X-ray absorption spectra atthe 0.2mm and 3mm probing positions, withcorresponding delay times of 180 and 880ns,respectively. The shapes of the absorptionspectra are identical irrespective of the delaylime. It is similar to the X-ray absorptionspectrum of C2 which is emitted from C60
S)
after laser irradiation. Figure 7 shows C2
absorption spectrum emitted from laserirradiated C60. This spectrum has ls-»n;*transition peak at 286cV. Therefore, it issuggested that the absorption peak of theablated slow particle at 286eV is originatedfrom the Is—»JC* transition of as C2.
o.o 280 300Energy [eV]
FIG.7. X-ray absorption spectra of G, from Qo.The irradiation laser energy density is0.5J/cnr.
References1) H.W.Kroto, J.R.Heath, S.C.O'Brien,
R.F. Curl and R.ESmalley, Nature 314.162(1985).
2) H.S.Carman.Jr. and R.N.Compton,Proc.2nd Inter.Conf. Laser Ablation,(1993).
3) A.Miyashita, O.Yoda, K.Murakami,T.Ohyanagi, S.Aoki and N.Yamaguchi,P roc. Laser Advcuiced MaterialsProcessing '92, 1029(1992).
4) EJannitti, P.Nicolosi and G.Tondello,Physica Scripta4J, 458 (1990).
5) S.C.O'Brien, J.R.Heath, R.F.Curl andR.ESmallcy, J.Chem.Phys. 88, 220(1988).
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JAERI-Rcview 95-019
6 . 1 8 Pulsed Laser Ablation of Silicon :Observation of particles emitted from Si surface andsputtering phenomena induced by laser-ablated particles
T. Ohynnngi, A. Miyashita^ K. Murakami and 0. Yoda*Inst. of Materials Science, University of Tsukuba,f JAERI Takasaki, Functional Material Lab. 11
1.Introduction
Soft X-ray absorption spectroscopy is a pow-erful technique for the observation of laser-ablated particles. Since X-ray absorption spec-troscopy can detect all emitted particles irrele-vant to their electronic states, whereas populartechniques such as luminescence spectroscopyand time-of-flight (TOF) spectroscopy mea-sure only limited particles: luminescence spec-troscopy detects excited states of particles andTOF spectroscopy detects particles long afterthe laser irradiation. We have used laser pro-duced plasma X-rays (LPX) as an X-ray source.LPX is a. pulsed X-ray source and thereby time-resolved measurements can be performed.
This paper reports tiinc-rcsolved measure-ments of laser-ablated particles emitted fromthe surface of the sample at very early timesand an observation of sputtering phenomenainduced by laser-ablated particles.
2.Time-resolved measurements of laser-ablated particles
Figures L shows the time-variation of theX-ray absorption by laser ablated Si particlesemitted from the surface of the sample. Theablation-laser energy densities are 7J/cm2 and15J/cm2, respectively. These figures are de-picted by taking the pea,k heights of the ab-sorption peaks which are considered to have thelargest X-ray absorption cross section of all thepeaks of each species (neutral Si atom (Si0) andSi ions with charges of +.1 up to +4). Since X-ray absorption cross sections are different foreach species, these figures are normalized so asthe maximum value of the peak height to beunity.
At an energy density of 15.1/cm2, highly
charged particles such as Si4+ are observed onlyduring laser irradiation (< 20 ns), whereas Si2+
and Si+ are observed at 120 ns. Moreover, Si0
are not observed at this energy density within120 ns. It is generally considered that evapo-ration in the thermal equilibrium occurs afterlaser irradiation, but above findings show evap-oration occurs in the non-thermal equilibrium.At an energy density of 7J/cm2, Si'1+ are notobserved, whereas Si0 are observed. The differ-ence between two energy densities comes fromthe temperature of the surface: the surfacetemperature at 15,1/cm2 is higher than that at7J/cin2. The surface temperature is very highjust after laser irradiation, but the temperaturedecreases with time. At higher temperature, Siions are considered to be much excited ther-mally. Consequently, highly charged ions suchas Si3"1" and Si2+ are produced. After the sur-face temperature decreases, low charged parti-cles arc predominant. Therefore, at an energydensity of 15J/cm2, Si0 must be observed muchlater than 120 us.
3.Sputtering phenomenalaser-ablated particles
induced by
We performed X-ray absorption measure-ments of laser-ablated Si particles with an Alplate which is placed just above the sample sur-face, as shown in Fig. 2. Typical results areshown in Fig. 3. The spectra, in Fig. 3 weremeasured at an ablation-laser energy densityof 5 J/cm2 with 1064 nm laser at various delaytimes. The measured positions of Figs. 3(a)and 3(b) are 0 mm and 0.6 mm above thesample surface, respectively. In Fig. 3(a), al-most all (he absorption peaks are due to Si0,Si+, and Si2+, but some unknown peaks are
- 1 7 0 -
JAERI-Rcvicw 95-019
also observed from SO cV to 90 eV. Moreover,in Fig. 3(b), tliorc are aiiollier two absorptionpeaks at 119.4 eV and 121.-1 eV, which are in-dicated by arrows in the figure. We performedmeasurements for laser-ablated Al particles,a.sshown in Fig. <1, because these unknown peaksmay be due to Al particles. The results indi-ca.tc that unknown peaks in Fig. 3 come fromAl atom and ions which are ejected from the Alplate surface by collisions with high-velocity Siparticles. Therefore, it has been found thatlaser-ablated Si particles can sputter Al ell'cc-tivcly.
4.ConclusionsThe time-resolved X-ray absorption mea-
surements of laser-ablated Si particles emittedfrom the Si surface has been performed. At. anenergy density of 15 -I/cm2, neutral Si atoms(Si") have not been observed within 120 us,whereas they arc observed al an energy den-sity of 7 J/cui2 . These results are consideredto come from the difference in the temperatureof the surface.
Moreover, we have observed sputtering phe-nomena, induced by laser-ablated Si particles.
£ oB 1
>'T3 0
0
• 15J/CTO'
o 7.l/rrn?
I I
I i | I I I
0 20 40 60 80 100 120Delay Time [ns]
Fig. 1. Time-variation of X-ray absorptionof laser-ablated Si particles.
I in m
Laser
/
Plume
:/ - Soft X-rays
Fig. 2. Schematic diagram of arrangement, ofsamples with respect to the X-ray beam.
- 171 -
JAERI-Review 95-019
u80 100 120 140 160 180Energy[eV]
0.4
0.2
oin
3
unklH)wit ponds
N 1 1 1 1 1 1
(I'l
ilnl.iy -
IHOm
1 1 1
100 120 140 160 180Energy[eV]
'c=3
xi
coQ.
OX3
100 120 140 160Energy[eV]
180
Fig. 3. X-ray absorption spectra, of laser-ablated Fig. A. X-ray absorption spectra, of laser-ablatedSi particles with a.n Al plate. The measured position Al particles. The measured position is (a) 0 mmis (a.) 0 mm and (b) 0.6 mm from the surface of Si and (b) 0.5 mm at 80 ns.bulk sample at various delay times
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JAERl-Rcview 95-019
6 . 1 9 Real Time RHEED Observation during CarbonThin Film Growth by Ion Beam Deposition
Hideki OHNO*, Yasushi AOKI and Siro NAGAI
Takasaki Radiation Chemistry Research Establishment, JAERI*Department of Physics, Meisei University
INTRODUCTION
Ion beam deposition (IBD) is a direct
method of producing thin films on substrates
using low-energy ion beams in an ultra high
vacuum (UHV). The use of this technique
in thin film growth is attractive in the
fabrication of advanced materials0' (i.e. low
temperature semiconductor epitaxial growth
and growth of metastable materials like a
diamond). IBD of diamond (-like) films has
been studied since 1971<2>. The possibility
of obtaining diamond (-like) thin film opened
up a wide field for their application for
electronic device. In the IBD, the ion energy
is the primary parameter that influences the
structure of grown carbon films, cither of
metastablc phase (diamond) or stable phase
(graphite). The fluenccof ion beam is another
important parameter. This report describes
the effects of these parameters on the crystal
stricture of films, investigated by means of
real time reflection high energy electron
diffraction (RHEED).
EXPERIMENT
The low energy ion beam deposition
apparatus used in this study has been
described in detail elsewhere'3'. The
arrangement of the real time RHEED
experiment is schematically shown in figure
1. The high-energy electron beam is incident
upon a sample at a glancing angle, and
produces diffraction patterns, RHEED
patterns,on afiuorescentscreen. The RHEED
patterns on the screen are photographed by a
CCD -camera controlled by a computer.
A Si(lll) sample cut into a 2 x 2
cm2 in size was, before being loaded into the
target chamber, chemically etched in HF
solution. After mounted on the sample holder,
the sample was cleaned by heating at about
500 °C for 5 hours, followed by at 800 °C
for about 5 minutes in a vacuum of about
10"9 Torr. The incident C+ ions employed
were either 10 eV or 100 eV in energy, about
2 pA/cm2 in current density and about 5 mm
in diameter as measured by means of a
Faraday cup. The pressure in the target
chamber was about 10'9 Torr during the
deposition. All of the RHEED patterns were
obtained by using a 25 keV electron beam.
The cross section of the beam is about 100
in diameter.
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JAERI-Revicw 95-019
RESULTS AND DISCUSSION
Photographs 1 ~ 4 in figure 2 are the
RHEED patterns observed for the case of 10
cV C" ion deposition. The pattern of
Photograph 1 which is obtained at room
temperature before deposition corresponds to
Si(lll) lxl structure, and the pattern at
fluence of 1015 ions/cm2 (Photograph 3)
suggests the existence of two kinds of
structure; Si with interatomic distance
3.71±0.05 A and SiC of epitaxially grown
cubic phase with interatomic distance
4.60+0.38 A. The deviation of the
experimental value from the standard lattice
constant (i.e. a = 4.3597 A) for SiC may be
due to the growth of SiC(lOO) plane on the
Si(lll) plane. The pattern of Photograph 4
observed at 1017 ions/cm2 includes weak ring
patterns which suggest polycrystallization of
film. The interatomic distance calculated
from the radius of the ring pattern is2.40 ±0.06
A. This value agrees well with the lattice
constant of graphite (i.e. a = 2.456 A).
The RHEED patterns observed during
100 eV C+ ion deposition were different from
those for 10 eV. The initial pattern due to
Si(lll) lxl structure changed to a diffuse
pattern corresponding to amorphous phase
at fluence of 1015 ~ 1016 ions/cm2. The
formation of amorphous phase is probably
due to implantation effect by incident ions.
The pattern atfluenceof 1017ions/cm2 showed
recrystallization which suggests hetcro-
epitaxial film growth leading to the diamond
(-like) film. The final pattern (Photograph
5 in figure 3) observed at 1018 ions/cm2
consists of streaks, which indicates that the
surface of the grown film is uniform. The
interatomic distance calculated for this
pattern (i.e. about 3.7 A) is near that of
diamond structure of carbon (i.e. 3.567 A).
SUMMARY
The real time RHEED observation
during film growth by ion beam deposition
has been successful for the first time. The
structure of carbon film by C+ ion deposition
depends on the energy and the fluence. The
results of AES(4) and RHEED experiments
summarized as follows. At 10 eV incident
energy, an initial cubic-SiC film (1016
ions/cm2) grows finally to a graphitic film
(1017). At 100 eV.an initial SiC film (1015)
in amorphous phase grows finally to a
diamond (-like) film (1017~1018) in crystalline
phase.
REFERENCES
(1) For example, K.G. Orrman-Rossitcr et
al, Nucl. Instr. and Meth., B59/60
(1991) 197.
(2) S. Aisenbergand R. Chabot.J. Appl.
Phys., 53 (1971)2953.
(3) H. Ohno, Y. Aoki and S. Nagai, JAREI-
Research 94-018 (1994).
(4) H. Ohno, Y. Aoki and S. Nagai, JAREI-
Review 94-005 (1994) 156.
- 1 7 4 -
JAERI-Review 95-019
Ion beam Fluorescent screen
Deceleration lens
CCD controller | | TV monitor 1 V i d e Q TV monitor 2
30keVElectron gun
Personalcomputer
Video printer
Fig. 1 Schematic diagram for real time RHEED measurement.
(2)
(3) (4)
Fig. 2 Change of RHEED patterns during 10 eV C+ ion beam
deposition. C+ fluences: (1) 0; original, (2) lxlO15, (3)
lxlO16, (4) lxlO17 (ions/cm2).
Fig. 3 RHEED pattern of the carbon thin film after 100 eV C+
ion beam deposition at fluence of 1018 ions/cm2.
- 1 7 5 -
JAERI-Review 95-019
7. Nuclear Chemistry and Radioisotope Production
7.1 Synthesis and Biodistribution of Rhenium-186 Labeled HEDP
N.Shigeta, H.Matsuoka, T.Sekine, A.Osa, M.Koizumi, K.Kobayashi,
S.Motoishi, K.Tomiyoshi, N.Oriuchi, N.Watanabe, K.Endo and
R.M.Lambrecht 179
7.2 Identification of the New Isotope 1 2 5 Pr and y -ray Spectroscopy
of the Decay of l 2 6 P r
A.Osa, M.Asai, M.Koizumi, T.Sekine, Y.Kojima, H.Yamamoto,
and K.Kawade 181
7.3 A Five-HPGe Detector System for y-y Angular Correlation
Measurement at the TIARA-ISOL
M.Asai, Y.Kojima, A.Osa, M.Koizumi, T.Sekine, M.Shibata,
H.Yamamoto and K.Kawade 184
7.4 Development of Laser Ion Source for the Study of Short-lived
Isotopes with the TIARA-ISOL
M.Koizumi, A.Osa, T.Sekine, T.Horiguchi and M.Asai 187
7.5 Determination of the Change of Nuclear Charge Radius in
the 81 keV Transition of I 3 3Cs Using ' 33Xe-implanted Sources
H.Muramatsu, H.Ito, M.Misawa, T.Miura, M.Koizumi, A.Osa,
T.Sekine, M.Yanaga, Y.Fujita, K.Endo, H.Nakahara and
M.Fujioka 190
- 177 -
JAERI-Review 95-019
7 . 1 Synthesis and Biodistribution of Rhenium-186 Labeled HEDP
N. Shigeta, H. Matsuoka, T. Sekine, A. Osa, M. Koizumi, K. KobayashiS. Motoishi, K. Tomiyoshi*, N. Oriuchi , N. Watanabe*, K. Endo andR. M. LambrcchtDepartment of Radioisotopes, JAERI, *School of Medicine, University ofGunma and **Department of Chemistry, University of Wollongong
Rhenium-186 is a p-emitting radionuclidewith a maximum j3 -emission of 1.07 MeV. Ithas a 9% abundant y -ray of 137 keV which issuitable for imaging. The physical half-life of90.64 h makes it a candidate for use as a bonepain palliation agent, such as 186Re-HEDP ( 1 -hydroxyethylidene-l,l-diphosphonate) and186Re-MDP (methylenediphosphonate), and asradioimmunotherapeutic Pharmaceuticals, whichare monoclonal antibodies labelled with 186Re.
186Re can be produced in the 185Re(n,y)186Rereaction with a nuclear reactor, meanwhile thepresent authors have succeeded in the productionof 186Re by the 186W(p,n)186Re reaction with aproton beam from a cyclotron [1]. We may saythat no-carrier-added 186Re produced withcyclotron is superior to a reactor-producedproduct for labelling monoclonal antibodies,although the specific activity is not worry for thebone pain palliation agent; we do not claim thatthe cyclotron-produced product is carrier-free,
since the stable 185Re isotope is probablyproduced by the 186W(p,2n)185Re reactionaccompanying the 186W(p,n)185Re reaction at acertain range of proton energies.
This paper reports experimental results on thesynthesis of 186Re-HEDP with both ofcyclotron-produced and reactor-produced 186Re.In addition, an image of 186Re-HEDP in a ratand a biodistribution of 186Re-HEDP in a mouseare given with reactor-produced 186Re.
The method of preparation of 186Re-HEDPfollowed that reported by de Klerk et al..[2], inwhich 186Re-HEDP was formed by reduction of186Re-perrhenate in the presence of SnCl2. Priorto synthesis of 186Re-HEDP, an HEDP kit wasprepared in a way as shown in Fig. 1 with afew modifications of that prescribed by de Klerket al. The preparation of the HEDP kit was donein an atmosphere of inactive gas and each of thelyophilized mixtures was sealed in a vacuum. The
resulting HEDP kit contained typically 10 mg ofHEDP, 3.85 mg of SnCl2-2H2O and 3 mg ofgentisic acid.
The radiochemical yield of 186Re-HEDP wasdetermined by thin layer chromatography. Withtwo-dimensional development using acetone asthe first solvent and 0.9%(w/v) saline as thesecond solvent, 186Re-HEDP, free perrhenateandreduced hydrolysed rhenium (186ReO^) wereseparated. The 186Re radioactivity of each of thecomponents was counted by radioluminography.
The 186Re samples used were solutions ofReO4~ in saline for cyclotron-produced 186Reand in water for reactor-produced Re. Theradioactivity concentrations were 0.25 MBq/m{for cyclotron-produced 186Re and 0.38 GBq/m«for reactor-produced 186Re. 1 m« of the 186Resolutions was mixed with the foregoing HEDP kitand heated at 98 °C for 10 min. Theradiochemical yield of 186Re-HEDP was foundto depend on pH, in particular for the cyclotron-produced 186Re. The radiochemical yield morethan 95% was obtained at pH 1.2.
To study the influence of the pH of thereaction mixtures on the percentage of 186Re-HEDP, the pH was changed to 2, 4, 5, 6, 7 and8 by addition of 0.1M CH3COONa, after the
50 \il of 60% HEDP solution
10.4 mg of gentisic acid
2 m£ of purified water —
Dissolution
9 vat of 0.1M HC1 contain-ing 11.57 mg of SnCl2
Division into three «irts
Lyophilization
Kept in the dark at 2 - 8 °C
Fig.l Preparation of the HEDP kit forsynthesizing 186Re-HEDP
- 179 -
JAERI-Review 95-019
20
15
Q 10
8
Fig.2 The percentage^ 186Re-HEDP at pHchange after the synthesis at pH 1.2;squares and black circles are for thereactor-produced and for the cyclotron-produced 186Re, respectively,
synthesis at pH 1.2. The results are shown in Fig.2. The reactor-produced 186Re-HEDP was littleaffected by the pH change, but the cyclotron-produced 186Re-HEDP decreased its percentageat pH higher than 5.
The pH of the 186Re-HEDP to be injected toanimals were adjusted to 4 by addition of 0.1MCH3COONa. Since the cyclotron-produced186Re-HEDP was unstable at the pH range ofsaline, an image and a biodistribution of 186Re-HEDP were obtained with the reactor-produced186Re. The 186Re-HEDP was injected into thetail vein of rats and mice.
The images of the 186Re radioactivity in a rat
R- BL
• 0.3 hrB3hrB 12 hr• 24hr
\ 1 I H-
Fig.3 An image of the 186Re radioactivityin a normal rat at 3 hr after
blood kidney stomach lung boneliver intestine spleen muscle
Organ
Fig.4 A biodistribution of the 186Re radio-activity in normal mice into which186Re-HEDP was injected.
were recorded with a gamma camera in 5-mincounting at 0.5 hr, 1 hr and 3 hr after injection;the image at 3 hr after injection is shown inFig.3. The mice were slaughtered at 0.5 hr, 3 hr,24 hr and 48 hr after injection. Samples ofdifferent organs were weighed and counted in awell-type gamma counter to calculate theresident radioactivity in each of organs. Theresults of the biodistribution, expressed as %injected activity per gram of tissue, aresummarized in Fig.4. The highest activity wasfound in the bones and the stomach. The residentactivities in the bones were 15.09% at 3 hr and12.02% at 24 hr. The activities in the stomachwere 1.83% at 3 hr and 0.33% at 24 hr afterinjection.
This work is a part of the study on rheniumisotopes carried out by the Isotope-Productionand Labelling Working group in the ResearchCommittee on Isotopes organized by JapanAtomic Energy Research Institute.
References(1) N. Shigeta, et al., JAERI TIARA Annual
Report 1993 (Vol.3), p.163 (1994).(2) J.M.H. de Klerk, et al., J. Nucl. Mcd., 33,
646 (1992).
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JAERI-Review 95-019
7 . 2 125,Identification of the New Isotope Pr and y-ray Spectroscopyof the Decay of 126Pr
Akihiko OSA, Masato ASAI*, Mitsuo Koizumi, Toshiaki SEKINE,Yasuaki KOJIMA*, Hiroshi YAMAMOTO* and Kiyoshi KAWADE*Department of Radioisotopes, JAERI and School of Engineering,Nagoya University
1. INTRODUCTION
The Xe-Ba-Ce isotopes in a transitional regionof nuclear deformation have been a subject ofexperimental and theoretical investigations.Experimental infonnation has been acquired forthe Xe isotopes in the broad range of the majorshell and for the Ba isotopes over the neutronmidshell (N=66) by means of in-bcam and decayspectroscopy, and collinear laser spectroscopy. Itis of interest to see if the strong systematicbehavior which was reported [1] for the Xe andBa nuclei is continued for Ce. Some irregularitiesobserved for the Ba nuclei around the neutronmidshell [2,3] should be checked experimentallyalso for Ce.
The most recently reported experiments10*7
constructed the level schemes of Ce69 [4, 5]for the lightest odd-A Cc isotopes, and identifiedthe rotational bands with the side bands of128Cc70 [6] for the lightest even-/! Ce isotopes;for I24Ce66 [7] and 126Ce68 [8, 9] the groundbands were known. The present work aims atextending the low-lying level systematics of Ceisotopes toward a more unstable region bystudying the p+ decay of Pr isotopes using theTIARA-ISOL [5] connected to an AVF cyclotronat the Takasaki site of JAERI. .
2. EXPERIMENT
The radioactivies of 125Pr and 12 Pr wereproduced with a Mo-enriched mettalic-foiltarget bombarded by a 5.4-MeV/u Ar beam.The experimental apparatus and techniques usedwere described elsewhere [5]. It should bepointed out that the beam intensity was increasedup to 0.2 particle uA on the average. Reaction
products were ionized and mass-separated asmetallic ion and monoxide ion; from a monoxide-ion beam the Ba isobar was removed to increasethe sensitivity of the detection of the Cc KaX-rayobscured by the Cs KnX-ray associated with thedecay of the Ba isobar, while from a metallic-ionbeam the La and Ce isobars were much reducedto enhance the signal/noise ratio in y-ray spectrafor the measurement of the decay of Pr nuclei[5]. y-singles, j3-gated 7 and y-y coincidencemeasurements were performed.
3. RESULTS AND DISCUSSION
3.1 Decay of the new isotope 125Pr
In the metallic ion beam with mass 125,a 135.76(5)-keV y-ray with a half-life of3.3(7) s was observed, as shown in Fig.l.The assignment of this y-ray to the decay of125Pr was supported by its coincidence withCe X-rays and P+ rays, and additionally bythe fact that the same Y"rav was not observedin the monoxide-ion beam, in which the Laand Ce isobars were more preferentiallycontained than the Pr isotope, as described insection 2. Another two yrays were identifiedfrom the coincidence data. A decay schemeof 125Pr was constructed, as shown in Fig.2,from the y-ray intensities. The 146.1(5)- and180.2(7)-keV transitions seem as members ofthe 5/2+ band for 125Ce reported in ref.[10].
3.2 Decay of 126Pr
In the metallic-ion beam with mass 126,
- 1 8 1 -
JAERI-Review 95-019
103
COcod•ioo
102- $
1
104
hann
el
CJ
"coO
i
i j t i
125Pr 135
in if) jtin J
: ?! -* I Id 8
T- (LL (I w
900 1000Channel Numberi i i i
t t
.8keV±0.7s
1 T
i i
= 3.3(7)s
CMO
+>co(9/2+)
(7/2+)
(5/2*)
•462.0+X
•W-281.8+X
135.8+x
• 0.0+x
0 2 4Time / s
Fig.l Y"raY spectrum of mass 125 and the decaywith timeof the 136-keV y-ray yields.
!67
Fig.2 The proposed decayscheme of 125Pr.
three prominent y-rays ascribable to thetransitions in the126Ce ground band [8] wereobserved. The half-life of 3.14(22) sdetermined for the 349.54-keV y-ray w a s ingood agreement with the reported values of3.2(6) s [11] and 3.0(4) [9] for 126Pr. Theenergies and relative intensities of the y-raysare summarized in Table 1. From the dataand the y-y coincidence relationships, thedecay scheme of 126Pr was constructed, asshown in Fig.3.
Assignment of the 954.2-keV level as the2+
2 band head for the y band is reasonablefor a nucleus in this region. This assignmentis supported by the presence of otherprobable members of a y band with spinparities of 3+ and 4+. The excitation energyof levels of the y band shows a continuationof the systematical trend of Ce isotopes [6].Although the experimental 2+
2-level energy,which lowers with decreasing neutronnumber until 132Ce, and then increasesslowly, jumps higher considerably at Ce,this trend is in good agreement with theprediction of the interacting boson model 2
(IBM-2) [1]. The branching ratio5(E2;2+
2^0+1)/5(E2;2+
2-^2+,) found to be0.24(8) (E2/M1 ratio 62=15.7 was assumedfrom the IBM-2 calculation) is also in goodagreement with the IBM-2 prediction [1].When the low-lying level structure of 126Ceobtained is compared with that of 122Ba[12],the pair of these nuclei with the same bosonnumber 11 is a good candidate for F spin
128, 124Tmultiplets like the pair (1/8Ce, U4Ba)suggested by Lu et ah [6].
This study will continue with the TIARA-ISOL facility, employing anotherexperimental techniques of conversionelectron and y-y angular correlationmeasurements.
REFERENCES1) G. Puddu, O. Scholten and T. Otsuka, Nucl.
Phys. A348 (1980) 109.2) A. Gizon, Invited talk given at the Int. Sym. on
Heavy Ion Phys. and its Application, Lanzhou1990.
3) T. Morikawa, M. Oshima, T. Sekine, Y.Hatsukawa, S. Ichikawa, H. Iimura, A. Osa, M.Shibata and A. Taniguchi, Phys. Rev. Lett. R6
- 1 8 2 -
JAERI-Review 95-019
Table 1y-rays associated with thedecay of 126Pr
Energy
(keV)
Relative
intensity
169.59(3)349.54(5)
496.0(1)
785.1(5)
818.1(2)
954.2(4)
985.1(4)
100(6)72(4)
27.7(19)
6.8(14)
6.1(9)
4.1(7)
8.3(12)
1337.2
(3*) 1154
(2+)^"X 818.1
954,2_\ (6.1)
T1/2 = 3.14(22)s
qCD
% 1015.1
519.13
126TFig.3 The proposed partial decay scheme of Pr
(1992) 46.4) B.M. Nyako, J. Gizon, V. Barci, A. Gizon, S.
Andre, D. Barneoud, D. Curien, J. Genevey andJ.C. Merdingcr, Z. Phys. A334 (1989) 513.
5) T. Sekine, A. Osa, M. Koizumi, S. Ichikawa, M.Asai, H. Yamamoto and K. Kawade, Z. Phys.A349 (1994) 143.
6) J. Lu, J. Mukai, T. Komatsubara , T. Hayakawaand K. Furuno, Z. Phys. A348 (1994)239.
7) K.L. Ying, P.J. Bishop, A.N. James, A.J. Kirwan,D.J.G. Love, T.P. Morrison, P.J. Nolan, D.C.B.Watson, K.A. Connell, A.H. Nelson and J.Simpson, J. Phys. G 12 (1986) L211.
8) C. J. Lister, B. J. Varley, R. Moscrop, W.Gelletly, P. J. Nolan, D. J. G. Love, P. J. Bishop,A. Kinvan, W. J. Thornley, L. Ying, R.Wadsworth, J. M. O'Donnell, H. G. Price, and A.H. Nelson, Phys. Rev. Lett. 55 (1985) 810.
9) D. Barn6oud, J. Blachot, J. Genevey, A. Gizon, R.Beraud, R. Duffait, A. Emsallem, M. Meyer, N.
Redon and D. Rolando-Eugio, Z. Phys. A 330(1988) 341.
10) K.L. Ying, P.J. Bishop, A.N. James, A.J. Kirwan,T.P. Morrison, P.J. Nolan, D.C.B. Watson, K.A.Connell, D.J.G. Love, A.H. Nelson and J.Simpson, Nuclear Structure Appendix to theDaresbury Annual Report (1986/87) 27.
11) J.M. Nitschke, M.D. Cable and W.-D Zeitz, Z.Phys. A312 (1983) 265.
12) T. Sekine, S. Ichikawa, M. Oshima, H. Iimura, T.Morikawa, A. Osa, W.H. Chung and Y.Hatsukawa, Proc. Int. Conf. on Evolution in Beam
Application, Takasaki, Japan, 1991, p.531.
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JAERI-Rcview 95-019
7 . 3 A Five-HPGe Detector System for 7-7 AngularCorrelation Measurement at the TIARA-ISOL
Masato ASAI, Yasuaki KOJIMA1, Akihiko OS A2,Mitsuo KOIZUMI2, Toshiaki SEKINE2, Michihiro SHIBATA1,Hiroshi YAMAMOTO1 and Kiyoshi KAWADE1
Department of Nuclear Engineering, Nagoya University,department of Energy Engineering and Science, NagoyaUniversity and 2Department of Radioisotopes, JAERI
1. Introduction
Xe-Ba-Ce nuclei around the A=130mass region are of interest in connectionwith various collective properties such as 7-softness and triaxiality. Band structures ofhigh-spin states in these nuclei have beenextensively studied by means of in-beam7-ray spectroscopy with heavy ion-inducedreactions. However, A knowledge of low-energy low-spin states, which are scarcelyexcited by the heavy ion-induced reactions,is still insufficient except for Xe isotopes.In recent experiments, low-spin states ineven-even Ba nuclei were studied with de-cay spectroscopy[1,2], but there are somedifficulties in spin assignments.
The 7-7 angular correlation measure-ment is an effective method to make spinassignments in decay spectroscopy. How-ever, this method requires a strong radioac-tive source or a long measuring time to ob-tain useful data, so that it is little used inon-line experiments on short-lived isotopes.In order to improve its efficiency, multiple-detector systems have been developed atvarious laboratories. Wolf et al.[3] and Ya-mada et al.[4] constructed four-Ge detectorsystems and measured 7-7 angular correla-tions for short-lived neutron-rich isotopesproduced by the 235U(ntii,f) reaction in on-line experiments using an isotope separatoron-line(ISOL).
In the present work, an efficient five-HPGe detector system for 7-7 angularcorrelation measurements was constructedat the TIARA-ISOL[5] to study low-spin
states populated via the /9-decay of short-lived neutron-deficient isotopes producedby heavy-ion fusion-evaporation reactions,and the performance of the system wastested with an 152Eu source in an off-lineexperiment. In an on-line experiment, low-spin states in 126Ba populated via the /3-decay of 12GLa(Ti/2=54 s) were investigatedwith this system.
2. Five-HPGe detector system
The system consists of five n-type coax-ial HPGe detectors whose relative efficien-cies are 33%, 33%, 29%, 28% and 28%, re-spectively. The detectors are configured atfixed angles, as shown in Fig. 1, which pro-vide ten correlation angles of 90, 100, 110,120, 130, 130, 140,150,160 and 170° simul-taneously. Each detector is placed 60 mm
Fig. 1. Configuration of five-HPGedetectors.
- 1 8 4 -
JAERI-Review 95-019
Table 1. Results of angular correlations for cascades in 152Sm and 152Gd from 152Eu decay.
Cascade[keV]152Sm245-1224 + -2 + -0 +
964-1222+-2+-0+
1112-1223+-2+-0+
1408-1222--2+-0+152Gd411-3444+-2+-0+
779-3443--2+-0+
A2
A4
A2
A4
A2
A4
A2
A4
A2
A4
A2
A4
Present work
0.069±0.0050.008±0.010
-0.012±0.0070.260±0.012
-0.202±0.007-0.062±0.013
0.179±0.0060.001±0.010
0.103±0.0110.016±0.020
-0.069±0.005-0.002±0.009
Wolf et al.[3]
0.090±0.013-0.012±0.015
-0.02 ±0.020.340±0.054
-0.239±0.030-0.070±0.065
0.172±0.0310.018±0.023
0.104±0.0096>0.015±0.0136>
-0.070±0.0056>0.002±0.007b>
Yamada et al.[4]
0.088±0.0l0-0.004±0.020
-O.O14±O.O1O0.299±0.022
-0.233±0.010-0.100±0.022
0.205±0.0100.013±0.020
0.107±0.0140.01 ±0.02
-0.066±0.006-0.004±0.009
Barrette ct al.[7]
0.1020±0.0015a)
0.003±0.003a)
0.017±0.005a)
0.320±0.022a)
-0.260±0.010a)
-0.082±0.014a>
0.227±0.008a)
0.003±0.008a>
0.101±0.0050.015±0.009
-0.063±0.010-0.010±0.025
a) Attenuation correction arising from a lifetime of the 122 keV state has been made.6> Values from Ref. [8].
from a source position. The end-caps of thedetectors are tapered so that the source-to-detector distance can be as small as 60 mmat 50°. The electronic system is similar tothat of Wolf et al. and Yamada et al. The7-7 coincidence events between any pairsof detectors are taken in a list mode withan LN-9000 multiparameter pulse-heightanalyzer (Laboratory Equipment Corpora-tion), with which 7-ray singles spectra foreach of the detectors are also taken simul-taneously.
A 23 kBq 152Eu source was used totest the performance of the system. About4.9 x 107 events were accumulated in the23 h measurement. To normalize the dif-ferent efficiencies of detectors, the singlescounts were used in this analysis. Effi-ciencies of constant fraction discriminatorswere almost 100% in the energy regionabove 30 keV. The coincidence counts AWn
for the cascade between 7-rays i and j werefitted to the following equation:
N™mn
where 0mn is the angle between the de-tectors m and n, S™ and Sf are the cor-responding singles counts, P2(cos6) andP4(cos 6) are the Legendre polynomials, AQ,A2 and A4 are fitting coefficients and Qiand Qi are the correction factors of fi-nite solid angle of detectors, which weremeasured by using a collimated sourcemethod [6] as a function of 7-ray energy.Results of the 7-7 angular correlations wereobtained for four cascades in. 152Sm andtwo cascades in 152Gd. The angular cor-relation coefficients Ai and A4 were sum-marized in Table 1. The results for thecascades in 152Gd were consistent with theprevious data within the experimental un-certainties. For the cascades in 152Sm, sincethe 122 keV state has a substantially longlifetime of 1.39 ns, the 7-7 angular corre-lations related to that state are attenuatedand the A2 and A4 values become small.If our Ai and A4 values for 152Sm are cor-rected with the attenuation fac .-> ,1 0.7 forAi and 0.8 for J44 which are deduced by fol-
- 185 -
JAERl-Review 95-019
lowing Barrette et al.[7], they become con-sistent with the literature values.
3. 7-7 angular correlation measure-ment for 1 2 6 Ba
In an on-line experiment, the 126Lanuclei were produced by the reaction94Mo(36Ar,3pn) at a beam energy of195 MeV. The beam intensity was about200 pnA on target. Reaction productswere mass-separated with the TIARA-ISOL, then collected on an aluminized My-lar tape in a tape transport system, andperiodically transported to the measuringposition equipped with the five-HPGe de-tector system. About 3.0 x 108 coincidenceevents were accumulated during a period of57 h.
From the results of the angular correla-tions, 0^ and O3" states were unambiguouslyidentified, and new 2+ and 4+ states and a1+ or 3 + state were assigned in 126Ba. Atypical result of the angular correlations isshown in Fig. 2. Besides, multipole mixingratios for several transitions were obtained.A detailed study of the low-spin level struc-ture in 126Ba is now in progress.
2-t/3
o
4
1-
1
1774keV
03+-2i
A 2 =
H
- 256keV ^
+- oi+ n0.305+0.030 /L O 6 2 ± O - O 5 7 .
90 120 1500(deg.)
180
Fig. 2. The 7-7 angular correlation forthe 1774-256keV cascade in 126Ba.
4. Conclusion
A five-HPGe detector system for 7-7angular correlation measurements has beenconstructed at the TIARA-ISOL. The sys-tem has been tested by using an 152Eusource. The A% and A4 values obtainedwere consistent with the previous data. 7-7 angular correlations in 126Ba have beenmeasured with this system in an on-line ex-periment. Good results to make spin as-signments and to determine multipole mix-ing ratios were obtained during a limitedmachine time of the cyclotron. It is con-cluded that this five-HPGe detector systemis considerably effective to measure 7-7 an-gular correlations for short-lived isotopes inon-line experiments.
References
[1] G. Siems, T. Fricke, U. Neuneyer, K.Schiffer, D. Lieberz, M. Eschenauer,I. Wiedenhover and P. von Brentano,Inst. Phys. Conf. Ser. 132 (1992) 675.
[2] K. Kirch, G. Siems, M. Eschenauer,A. Gelberg, R. Kiihn, A. Mertens, U.Neuneyer, O. Vogel, I. Wiedenhover,P. von Brentano and T. Otsuka, Nucl.Phys. A587 (1995) 211.
[3] A. Wolf, C. Chung, W.B. Walters,G. Peaslee, R.L. Gill, M. Shmid, V.Manzella, E. Meier, M.L. Stelts, H.I.Liou, R.E. Chrien and D.S. Brenner,Nucl. Instr. and Meth. 206 (1983) 397.
[4], S. Yamada, T. Sharshar, K. Okano andK. Aoki, Nucl. Instr. and Meth. A316(1992) 276.
[5] T. Sekine, A. Osa, M. Koizumi, S.Ichikawa, M. Asai, H. Yamamoto andK. Kawade, Z. Phys. A349 (1994) 143.
[6] B. Herskind and Y. Yoshizawa, Nucl.Instr. and Meth. 27 (1964) 104.
[7] J. Barrette, M. Barrette, A. Boutard,G. Lamoureux and S. Monaro, Can. J.Phys. 48 (1970) 2011.
[8] I-I. Helppi, A. Pakkanen and J. Hattula,Nucl. Phys. A247 (1975) 317.
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JAERI-Review 95-019
7 . 4 Development of Laser Ion Source for the Study ofShort-Lived Isotopes with the TIARA-ISOL
Mitsuo KOIZUMI, Akihiko OSA, Toshiaki SEKINE, TakayoshiHORIGUCHI*, and Masato ASAI**Department of Radioisotopes, JAERI*Department of Science, Hiroshima University**School of Engineering, Nagoya University
1. Introduction
An isotope separator on-line (ISOL) hasbeen constructed at the TIARA AVF cyclotronfacility. Experiments with it on neutron deficientnuclei in the rare-earth region, which wereproduced in heavy-ion fusion-evaporationreactions, have been carried out to identify newisotopes i27pr and i25pr[i.3].
The ion source of an ISOL takes animportant role to provide an ion beam of thenucleus of interest, containing less amounts ofthe isobars to obtain good signal to noise ratiosin radioactivity measurements following theisotope separation. To reduce the isobars, an ionsource technique with element selectivity for asurface ion source was developed by Ichikawa etal.[4] and applied to the above experiments; theelement dependence of the yield of monoxideions at high temperature was used. This ion-source technique is, however, applicable only tospecific elements, and a new method, which canbe applied to a broad range of elements in theperiodic table, is expected to be developed.
Ion beam
Extraction electrode Filament
Target and ionization chamber
Fig. 1. Schematic diagram of a laser ion source.
We have started the development of alaser ion source[5], based on a technique ofresonance ionization. In this ion source, atomsare excited stepwise to the ionization limit bytwo or three laser beams tuned to relevantatomic transition energies. Because of thedifference in atomic transition energies betweenelements, the process has high selectivity onelements.
2. The ionization efficiency of a laserion source
Figure 1 shows a schematic diagram of ahot cavity-type laser ion source, which isapplicable to the present surface ion source witha few modifications. In the hot cavity, heatedatoms fly between walls until they escape
through an orifice. Before leaving the cavity, anatom makes N-time flights. The number offlights N can be approximated by Atotai/Aorifice,where Aorifice is the area of the orifice, andAtotai the total surface area of wall inside thecavity.
The ionization efficiency of a laser ion
source, £JJ, is roughly written as
" U l 1 1 int '"laser'
where 8iascr is the resonance ionizationprobability of an atom in a pulsed laser field andPint the probability that the laser beam irradiatesthe atom during a flight.
The averaged period of time of a flight,
Atnight, is estimated from the equation given
later to be about 10 us. It is much longer thanthe laser pulse width, which is typically about10 ns, and shorter than the interval between
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JAERI-Rcview 95-019
laser irradiations, even with a laser of highfrequency as much as 10 kHz; the laserirradiation is less than one time during a flight.The laser interaction probability Pim is, hence,
proportional to the Atfiight and the laser repetition
rate vIaser, and is then given by
£ ;_. », AIn-V,laser
in! laserJ l flight \ftotal
where Vtotal and V]aSer indicate the entire volumeof the cavity and the effective volume of laserirradiation, respectively.
When the atom flies with a mean velocity
v for an averaged distance 1, the Atflight iswritten as
1J_V
where M is the mass of the atom, T thetemperature of the cavity, and k the Boltzmannconstant. The efficiency of laser ionization isthen given by
1 laser
'laser*total
For a typical ion source of 5-mm diameterand 50-mm length with a 1-mm-diameterorifice, heated to a temperature about 2000 K,the mean velocity v of an atom with a mass of100 is estimated to be about 500 m/s andN-1000. With a 50-Hz repetition-rate laser, the
Eu is estimated to be 15% on conditions that thelaser power is sufficiently large to saturate the
efficiency of resonance ionization (Eiascr = 1),and that V|aser/Vtotai = 0.15. The derived value issufficiently large to apply the laser ion source toour experiments.
3. A resonance ionization test system
To search for a suitable excitation scheme,and to monitor the laser wavelengths during an
experiment, a resonance ionization test systemequipped with a time of flight (TOF) massanalyzer has been installed. Figure 2 is aschematic diagram of this system, in whichNd:YAG laser (Continuum, Powerlight 6050:70-mJ output power at 532 run, 50-Hzrepetition rate) pumps two dye lasers (LambdaPhysik, FL3001) and half of the output fromthe Nd:YAG laser is used as the third step laserfor ionization. The wavelengths of the dyelasers are monitored by a wavemeter (Burleigh,WA-4500) and a laser galvanometer (Hamamatsu). The atomic beam from an oveninteracts with laser beams injected at the rightangle. The resulting ions are accelerated byelectric fields and transferred to an ion detector(Murata, Ceratron EMT-6081B) placed about 1-m away from the ionization region.
Resonance lonization lest chamberTOF mass analyzer
Fig. 2. Resonance ionization test system.
Sodium was chosen for examining theresonance ionization test system with the three-color and three-step transition scheme as seen inthe fig. 3 (a). The 1st transition used was the Ditransition. Dependencies of resonance ionizationsignals on the laser power were measured. Thespot size of the laser beams at the interactionregion was 5 mm in diameter; the maximumpower of the Nd:YAG laser was 350 mW andthose of two dye lasers were in the range from
100 to 500 (iW. (Accurate measurement was
- 1 8 8 -
JrtERI-Review 95-019
not possible at that time because of the lack of apowermeter for low power measurement.)Figure 3 (b) shows the observed powerdependencies. The measurements were carriedout under the condition that the power of each oftwo dye lasers was kept maximum except that ofa laser examined. Scales are normalized atmaximum power and at maximum yield. It isclearly seen that the 1st and the 2nd transitionsare almost saturated at the maximum hserpower. On the other hand, the 3rd transition isnot saturated at the maximum power, asexpected from its transition to the continuumlevels above the ionization potential. To realizean efficient laser ion source, therefore, a thirddye laser is needed to excite to a Rydberg stateor an autoionization state.
4. Summary
Development of an element selective laserion source has been started. The resonanceionization test system has been ready forstudying ionization schemes, and for monitoringlaser wavelengths.
To realize an efficient laser ion source forthe ISOL experiment, we have a plan forinstalling a high frequency excimer laser (400Hz) and another dye laser. Design of a laser ionsource for the TIARA-ISOL is also in progress.
References
[1] T. Sekine, S. Ichikawa, and Y. Hatsukawa, Proc. of
the 2nd Int. Symp. on Advanced Nucl. Energy
Research - Evolution by Accelerators-, 1990 (Mito,
Japan).
[2] T. Sekine, A. Osa, M. Koizumi, S. Ichikawa, M.
Asai, H. Yamamoto, and K. Kawade; Z. Phys.A349
(1994) 143.
[3] A. Osa, M. Asai, M. Koizumi, T. Sckine, S.Ichikawa, Y. Kojima, H. Yamamoto, and K. kawade,Nucl. Phys., A588 (1955) 185c.
[4] S. Ichikawa, T. Sekine, H. limura, M. Oshima andN. Takahashi, Nucl. Instr. and Meth. A274 (1989)256.
[5] M. Koizumi, T. Sekine, and A. Osa, Proc. of the6th Int. Symp. on Advanced Nucl. Energy Research- Innovative Laser Technologies in Nuclear Energy - ,Mito, Japan (1994), p.358.
a)
JI.P.4.l6eV
i
i
as.
1 532nm
568.44nm
1 589.755 nm
1.2
0.2 0.4 O.6 0.8Laser Power [a.u.]
Fig. 3. a) Partial energy levels of Na, and b) laser powerdependences of the resonance ionization signal.
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JAERI-Rcvicw 95-019
7 . 5 Determination of the Change of Nuclear Charge Radius inthe 81 keV Transition of 133Cs Using 133Xe-Implanted Sources
H.Muramatsu1, H.Ito1, M.Misawa1, T.Miura2, M.Koizumi3, A.Osa3, T.Sekine3,M.Yanaga4, Y.Fujita5, K.Endo6, H.Nakahara7 and M.Fujioka8
'Faculty of Education, Shinshu University, 2National Laboratory for High EnergyPhysics, ^Department of Radioisotopes, JAERI, 4Jikei University School of Medi-cine, 5INS, University of Tokyo, °Showa College of Pharmaceutical Sciences,7Faculty of Science, Tokyo Metropolitan University, 8CYRIQ Tohoku University
1. Introduction133Cs is the only Mflssbauer nuclide of alkali
metals for which both the Mflssbauer effect andthe internal conversion electrons can bemeasured in the same transition. Therefore, itis an invaluable probe for the elucidation ofthe nature of chemical bindings of highly ioniccompounds. The Mflssbauer isomer shift(6)expressed as a product of an atomic quantity,the difference of electron density at the nucle-usAp(0), and a nuclear quantity, the change ofnuclear charge radius AR/R. Thus, an exactknowledge of AR/R is essential for a quantita-tive interpretation of the isomer-shift data interms of a change in the electron density.
The value of AR/R for the 81 keV transi-tion of 133Cs has been proposed by severalauthors in the theoretical or Mflssbauer-measurement approaches [1-4]. However, itsmagnitude is still in controversy; the proposedvalue ranges from 0.15xl0'4 to 2xl(T4. Thesedeterminations except for the nuclear-theorycalculation]!], however, are based mainly onthe Mflssbauer measurement and the hypotheti-cally defined cesium configurations. In thisreport, the preliminary result for the determi-nation of the AR/R value in 133Cs by using theconversion method[5,6] is described.
2. ExperimentalThe source sample in this work was pre-
pared by the implantation of 133Xe(T./2=5.25d), which decays to the Mdssbauer level of133 Cs. Radioactive 133Xe gas was purchasedfrom LMRI(France) with a carrier gas of 3cm3 natural xenon. Ion-implantation of 133Xewas carried out at a terminal voltage of 20 kVat room temperature by means of an electro-magnetic isotope separator of JAERI (locatedat Takasaki). As host materials, a Zn foil anda Mo foil were chosen for the ion-implantation of 133Xe. The 133Cs Mossbauer
spectra were measured while keeping both thesource and absorber at liquid-helium tempera-ture, using a single-line absorber, CsCl with360 mg/cm2 Cs thickness. The 81 keV y-raysof 133Cs from the implanted source were de-tected with a thin Nal(Tl) scintillation detec-tor. A constant-acceleration drive with atriangular velocity shape was used at + 4 mm/s.
The internal-conversion electron spectra ofthe same samples that were used in Mflssbauermeasurement were measured using the INSjt/2~ iron-free (3-ray spectrometer having p=75cm. For measurements of the internal-con-version electrons, a single-wire proportionalcounter(SWPC) with a multislit(49 slits, 0.5mm slit-width) was used as a focal-planedetector. In order to reduce counter back-ground by using a position-coincidence tech-nique, the same type of SWPC was placed justbehind the main counter. The sample sourcewas covered with an aluminum slit for defin-ing the source dimensions to 0.5 x 20 mm2. Amomentum range of about 4% could bemeasured simultaneously.
3. ResultsFig.l shows typical conversion-electron
spectra of the Mo source in the region of theL-, M-, N- and O+P-lines of the 81 keVtransition in 133Cs. The momentum resolutionwas 0.05%, though the spectrometer resolu-tion was set at 0.03% momentum resolution.The conversion spectra were analyzed by aleast-squares fitting using the computer codeACSEMP[7]. In the M, N, O and P shells, notall the subshells were completely resolvedunder the present experimental conditions.
Fig.2 shows a typical Mflssbauer spectrumfor the Mo source. The spectra were analyzedby a least-squares method. The Mflssbauerspectrum of the Zn sample could be fitted witha doublet having a small quadrupole splitting;
- 1 9 0 -
JAERI-Revicw 95-019
X 1
Cou
nts
0
t I i i |
|
1M 1
JI t t f |
1 I 1 l 1 1 1
-
L2
1 * 1 * 1 * 1
1
0
1 1 t 1 1 1 1 1 I I I 1 I 1
1
1 t '
/ /i ' .
1 1 1 ) | | 1 1 1 1 1 1 1 1
955 960 1000
smis
sion 8
Rel
ativ
e T
ran
is
• •
-
4
1 1 1-2 0 2
Velocity (:nm/s)
.* * •
-
i
A
965 985 990 995 990
Electron Momentum (Gauss- cm)Fig. 1. The L-, M-, N- and O+P-conversion lines of the 81 keV transition in 133Cs.
density, po s(0)/p4 s(0), is equated with(ap+ap)/am, the equation for the isomershift can be written as
5=(4/5)jtZe2R2(AR/R)p4s(0)thcorA[(ao+ocp)/aN1].
The ratio ( a o +a p ) / a N 1 obtained fromconversion measurements was found tochange from 0.216(17) for the Mo sample to0.227(25) for the Zn sample. Using the rela-tivistic value of P4s(0)theor =1344.7 a.u.[9] andR=1.2xA1/3 fm, a tentative value, AR/R-+0.5x10^ was deduced from the correlationbetween 6 and (ao+ap)/aN r
References[1] R.A.Uher and R.A.Sorensen, Nucl. Phys.
86(1966)1.[2] G.P.Perlow, A.J.F.Boyle, J.H.Mershall and
S.L.Ruby, Phys. Lett. 17(1965)219.[3] A.J.F.Boyle and G.J.Perlow, Phys. Rev.
149(1966)165.[4] W.Henning, D.Q.Quitmann, KSteichele, S.Hufiier
and P.Kienle, Z. Physik, 209(1968)33.[5] H.Muramatsu, T.Miura, H.Nakahara, M.Fujioka,
ETanaka and A.Hashizume, Hyp. Int.l5/16(1983)269;20(1984)305.
[6] T.Miura, Y.Hatsukawa, M.Yanaga, K.Endo,H.Nakahara, M.Fujioka, E.Tanaka and A.Hashizume,Hyp. Int.28(1986)857; 30(1986)371.
[7] M.Fujioka and M.Takashima, J.Phys.40(1979)C2,32.[8] I.M.Band, LA.Sliv and M.B.Trzhakovskaya, Nucl.
Phys. A156(1970)170.[9] I.M.Band and V.I.Fomichev, Atom. Data and Nucl.
Data Tables, 23(1979)295
Fig. 2. Mdssbauer spectrum of133Xe implantedinto Mo. Source and absorber were at 4.2K.
the isomer shift was deduced to be -0.16mm/s, although the absorption intensity wasvery small. For the Mo sample, however, thespectrum indicated that there is more than oneabsorption peak, i.e. the radioactive atomswere introduced by implantation into morethan one site. Therefore, the averaged isomershift (5) of the source sample was estimated tobe -0.02 mm/s by using recoilless fractionsfor different sites and the site-population ofthe implanted atoms.
Since the valence-shell conversion cannot be separately measured, the followinganalytical method was used for the derivationof AR/R using the proportionality of theconversion coefficient to the electrondensity[8]. If the ratio of the outer-shellelectron density including the valence andnext-inner shell electrons to the 4s-electron
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JAERI-Review 95-019
8. Radiation Shielding for Accelerator Facilities
8.1 Radiation Streaming Measurement in a Labyrinth of
Light Ion Room 2 at TIARA
Su.Tanaka, H.Nakashima, Y.Nakane, Y.Sakamoto, S.Meigo,
S.Tanaka, M.Takada, T.Kurosawa, T.Nakamura, H.Hirayama,
N.Nakao, Y.Uwamino, M.Imamura and K.Shin 195
8.2 Measurements of Neutron Spectra from Stopping-length Targets
Bombarded with Light Ions
S.Meigo, H.Takada, H.Nakashima, T.Sasa, Su.Tanaka, K.Shin,
and Shinji Ono 198
8.3 Study of 7Li(p,n) Source Spectra and Neutron-induced Charged-
particle Emission Cross Sections at TIARA
M.Baba, T.Iwasaki, T.Kiyosumi, T.Sanami, Y.Nauchi, N.Hirakawa,
T.Nakamura, Su.Tanaka, H.Nakashima, S.Meigo, N.Hirakawa,
Sh.Tanaka and N.Nakao 201
8.4 Measurements of Neutron-induced Activation Cross Sections
at JAERI-Takasaki
M.Imamura, S.Shibata, T.Shibata, Y.Uwamino, T.Nakamura, E.Kim,
A.Konno, Su.Tanaka and Shun.Tanaka 204
8.5 Measurements and Analyses on Neutrons Transmitted through
Iron and Concrete Shields in Intermediate Energy Region
H.Nakashima, N.Nakao, Sh.Tanaka, T.Nakamura, K.Shin, Su.Tanaka,
Y.Sakamoto, H.Takada, S.Meigo, Y.Nakane and M.Baba 206
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JAERI-Rcvicw 95-019
8 . 1 Radiation Streaming Measurement in a Labyrinth ofLight Ion Room 2 at TIARA
Su. Tanaka, H. Nakashima2, Y. Nakane2, Y. Sakamoto2, S. Meigo2,S. Tanaka3, M. Takada4, T. Kurosawa4, T. Nakamura4, H. Hirayama5,N. Nakao6, Y. Uwamino5, M. Imamura6, K. Shin7
Ion Beam Eng. Dev., JAERI/Takasaki, Applied Radiation. Lab., JAERI/Tokai2,Office of Planning., JAERI/Tokyo\ Cyclo. R.I. Center, Tohoku Univ.4,Radia. Safety Cont. Center, KEK5, Insti. for Nucl. Study, Univ. Tokyo5,Faculty of Eng., Kyoto Univ.7
I. IntroductionIt is important to estimate radiation
streaming through a labyrinth as well asradiation transmission through a bulk shieldfor shielding design of high-energy acceleratorfacilities. Benchmark data of the radiationstreaming are required to confirm theapplicability of empirical formulas and MonteCarlo transport codes which are generallyused for the shielding design, and to make anew calculation method.
Hence, a streaming experiment has beencarried out using a p-Cu white neutron sourcegenerated by protons of 67 MeV in a labyrinthof Light Ion Room 2 at TIARA"- 2>. A planview of the experimental geometry is shownin Fig.l. The benchmark data measured inthis experiment are divided into threecategories: a characteristic of neutron source,radiation distribution in the target room, andradiation distribution along the labyrinth.
Detailed analyses for measured data wereperformed to get neutron spectrum, neutronflux and dose equivalent rate along thelabyrinth.
II. ExperimentalBoth energy spectrum and angular
distribution of the neutron source weremeasured by activation detectors of Al, Ti, Ni,Co, Nb, In, Au and Bi, where 209Bi(n,xn)reactions were used to measure neutronsabove 20 MeV-1' together with conventionalactivation detectors. During the experiment,the neutron source intensity was monitoredwith two fission detectors placed near the Cutarget and with a Farady cup. Distributions offission rates, thermal neutrons and gamma-rayexposure in the target room were measuredusing a 232Th fission counter (Centronic FC-480) and TLDs (Harshaw TLD100, TLD700).Besides, energy spectrum by a BC501A(BICRON) scintillator and a Bonner balldetector, neutron doses by a rem counter(Studsvik 2202D) and a solid state nucleartrack detector(Nagase Landauer Ltd.), andgamma-ray exposure by TLDs were measuredalong the labyrinth from the mouth.
1st, 2nd log
3rd leg
Sfclionul view of maze
0 1.5 m
I. —I @ ; points for metLsurvmenlof all quantities
o : points for measurtmtnt of dose and intensity
Fig. 1 Plan view for streaming experiment
- 195 -
JAERI-Rcview 95-019
III. Results and discussionFigure 2 demonstrates typical examples of
neutron spectra measured by the BC501A andthe Bonner ball detector along the labyrinth.The absolute values given by detectors aredifferent, especially at No. 14 position. Theupper neutron energy ends are about 35, 20and 10 MeV at first, second and third legs,respectively, which shows the energydegradation through the labyrinth. Slowneutron flux whose energy is below the"Cadmium cutoff" of about 0.5 eV is shownin Fig.3. The two values measured by theBonner ball and the TLDs are in reasonableagreement within the error of measurements.In Fig.4, dose equivalent rate of neutronsmeasured by the rem counter is compared withthe calculation using the neutron spectrameasured by the Bonner ball. The doseequivalent values by the Bonner ball givelarger values than those by the rem counter,and this difference becomes larger with thedistance along the labyrinth, about twice at thelargest distance. Dose attenuation rates alongthe labyrinth measured with the rem counterare shown in Fig.5, comparing with the doserate calculated by the Tesch's formula4'.
Figure 5 also includes neutron intensitiesmeasured with the track detector bynormalizing all values at the mouth of thelabyrinth to unity. The attenuation profilesthrough the labyrinth are similar for the remcounter and the track detector.
In order to analyze the data measured bythe activation detector, measurements of crosssection and preparation of library are inprogress.
References1. S. Tanaka and T. Nakamura, "Shielding
Experiments and Analysis at 90 MV AVFCyclotron Facility, TIARA," Proc.OECD/NEA Specialists' Meeting onShielding Aspects of Accelerators,Arlington, Texas, USA 28-29 April 1994
2. Su. Tanaka et al., "Measurement ofBenchmark Data for Radiation Streamingthrough Labyrinth(I)", JAERI TIARAAnnual Report 1993(Vol.3), (1994)
3. M.Imamura et al., "Measurements ofNeutron-induced Activation Cross Sectionat En=41.5 and 64.3 MeV", JAERI TIARAAnnual Report 1993(Vol.3), (1994)
4. K.Tesch, Particle Accel., 12, 169(1982)
1 0 '
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Fig.2 Energy spectra of neutrons measured by BC501A and Bonner ball detector
- 196 -
JAERI-Rcview 95-019
106
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Fig.3 Thermal neutron flux measured by Bonner ball detector and TLDs
1 0 6 g • » • i I • • ' • I
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IO1
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Fig.5 Dose attenuation rate measured by rcm counter and track detector
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JAERI-Rcview 95-019
8 . 2 Measurements of Neutron Spectra from Stopping-Length Targets Bombardedwith Light Ions
Shin-ichiro MEIGO, Hiroshi TAKADA, Hiroshi NAKASHMA,Toshinobu SASA, Susumu TANAKA*, Kazuo SHIN** and Shinji ONO**Department of Reactor Engineering, JAERI, *Advanced Radiation TechnologyCenter, JAERI and **Department of Nuclear Engineering, Kyoto University
IntroductionApplications of high energy particle
accelerators are increasing in a variety of fieldssuch as an actinide transmutation system, anintense neutron source and a medical therapy.In the neutronics design study of the facilities,nucleon-meson transport code such asNMTC/JAERI[1] has beer} employed. Thecode had been generally designed to treatnuclear reaction and transport for the highenergy particles above a few hundred MeV. Ameasured neutron spectrum is required tovalidate and improve the codes when they areapplied to low energy particles. The number ofexperimental data of those, however, is stillvery small.
In order to obtain the neutron yields of vari-ous targets, we started to measure neutronspectra using light ions[2]. In the presentstudy, the neutron spectra from stopping-lengthtargets bombarded with protons were meas-ured using Time-of-Flight (TOF) techniquewhich was superior to unfolding techniquewith respect to both the energy resolution andaccuracy. The measured data were comparedwith the calculated results of NMTC/JAERI.
ExperimentalThe measurements were carried out at the
HB-1 beam course at the AVF-cyclotron in theTIARA facility. The experimental arrange-ment is shown in Fig. 1. The thick targets ofcarbon and gold were bombarded with 67MeV pulsed protons of 3 ns in FWHM and320-ns-interval. The number of injectedprotons was counted with a digital currentintegrator (ORTEC 439) connected to thetarget that was surrounded by a -500Vsuppressor grid to repel secondary electrons.The diameter of the target was 30 mm, and thethickness was 33 mm for carbon and 6 mm for
gold, which was enough to completely stop theincident protons. The self-absorption ofproduced neutrons was negligibly small.Neutrons were measured by the TOF methodwith an organic scintillator (BC501A) of 12.7cm in diameter and 12.7 cm in length atemission angles of 0°,15o,30o,45o,60o,90° and120°, respectively. The flight path was 5.0 mfor the measurements between 0° and 45°, and2.5 m for those between 60° and 120°.
The BC501A scintillator was opticallycoupled to a HAMAMATU-R4144 photo-multiplier tube. Three signals, pulse height,pulse shape and TOF were accumulated by athree-parameter data acquisition system. Thepulse height was calibrated by the standardsources of 6()Co (Ey 1.17 ,1.33 MeV) and Am-Be (Ey 4.43 MeV). In order to discriminatebetween neutron and gamma-rays pulses, apulse shape discriminator having widedynamic-range over 500:1 was employed.
The contribution of the backgroundneutrons caused by the room-scattering wasmeasured at every angle using a rectangulariron block with the size of 20 x 20 x 40 cm3.
Data ReductionThe neutron TOF spectra were obtained by
an off-line discrimination between the neutronand gamma pulses. By the following equation,the neutron energy spectrum was transformedfrom TOF spectrum,
cf'n dn dt . . . . _ . _ ,
dEdQ. dl dE
where, dn/dt is the neutron TOF spectrum, Npthe number of incident protons, e detection effi-ciency and A£2 the solid angle sustained by thedetector to the center of the target.
The detector bias was set at half height of60Co Compton edge (1.074 MeVee). This en-ables us to obtain the neutron spectra above 4
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JAERI-Review 95-019
MeV. The detection efficiency for the bias wascalculated with SCINFUL[3] which includedmodified deuteron light output[4] and the angu-lar distribution of H(n,n) reaction cross-section[5].
CalculationIn the calculation, NMTC/JAERI code was
employed to simulate nuclear reaction and par-ticle transport calculations above 20 MeV. Inthe code, Pearlstein Systematics[6] was used totreat nucleon-nucleus collisions correctly. Thetransport of the neutrons with energies below20 MeV was calculated by the code MCNP-4A[7].
Moreover, the calculations including thepreequilibrium model proposed by Ishibashi etal.[8] were also performed, because it has beenpointed out [9] that the preequilibrium processshould be taken into account in order to im-prove the accuracy of the code in energiesbelow 160 MeV. For convenience, we callhereafter the calculation with the defaultversion of NMTC/JAERI as "2-step calcula-tion" and the one including the preequilibriumprocess as "3-step calculation".
ResultsThe resolution and the uncertainty of the
experimental data were smaller than 8% and10 %, respectively, in energies below 50 MeV.These values were much smaller than the onesobtained by the unfolding technique.
In Figs. 2 and 3, the calculated results arecompared with the experimental ones for C andAu, respectively. It is observed in both figuresthat the 2-step calculation significantly over-estimates the experimental neutron spectra inenergies above 20 MeV, which comes from theintranuclear cascade process, by factor of 3 to10 at forward angles from 0° to 30°. For thebackward neutron emission beyond 90°, theresults of 2-step calculation fall off steeply withincreasing energy, and so they are too smallcompared with the experimental results. Onthe other hand, the 3-step calculation predictsthe backward neutron emission in energiesabove 20 MeV fairly well. The increase in theyield of the neutrons with the energies above
20 MeV leads to diminish the excitation energyof a residual nucleus so that the yield of theevaporation neutron decreases. The 3-stepcalculation agrees well with the experiment inthe evaporation part which corresponds toenergies below 10 MeV. For energies above20 MeV, however, the calculation stilloverestimates the experiment.
SummaryWe have measured neutron spectra from
stopping-length C and Au targets bombardedwith 67 MeV protons. The minimum energyof measured ones was 4 MeV.
It has been found through the comparisonbetween the experimental and the calculatedresults that inclusion of the preequilibriumprocess improves the accuracy of calculatedones for the backward neutron emission andthe evaporation part in the forward angles. Inorder to improve the overestimation byNMTC/JAERI for neutron spectra at forwardangles of 0° to 30°, it is necessary to modifythe intranuclear cascade model taking intoaccount the nuclear medium effects such as thereflection and refraction.
References[1]Y. Nakahara and T. Tsutui, JAERI-M 82-
198(1982), (in Japanese).[2]K. Shin et. al, TIARA Ann. Rep. 1993 Vol.
3 (1994).[3]J. K. Dickens, ORNL-6462 (1988).[4]S. Meigo, et al., JAERI-Review 94-009
p.268 (1994).[5]R. A. Arndt, et al., Phys. Rev., D35, 128
(1987).[6]S. Pearlstein, Astrophys. J., 346^ 1049
(1989).[7]J. F. Briesmeister, (Ed), LA-12625 (1993).[8]OECD, "Intermediate Energy Nuclear Data:
Models and Codes", OECD publications,Paris, (1994).
[9]K. Ishibashi, et al.: "Proc. of Int. Conf. onNucl. Data for Sci. and Technol. Gatlin-burg, Tennessee, May 9-13, 1994, p571,(1994).
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ScatteringChamber(60cm <}>)
320 ns
JAERI-Review 95-019
| i :500Vn O _ Target Iron Block
,(C,Au) (Shadow Bar)
6 (deg.): 0,15, 30,45,60,90,120
L (m): 2.5, 5.0
Fig. 1 Illustration of the experimental arrangement
1010
108
106
CD
<U
I io4
10z
10°
67MeV p on C Disk(30mm diam. x 33 mm)
O ExperimentNMTC_2STEPNMTC_3STEP
1010
^ 10 B
106
2>-
I io4
<u
10"
10u
67MeV p on Au Diski(30mm diam. x 6 mm)
ExperimentNMTC_2STEPNMTC_3STEP
0 10 20 30 40 50 60 70 80Neutron Energy (MeV)
Fig. 2. Neutron energy spectra for 67 MeVproton incidence on stopping-length Ctarget. The dashed and the solid linesstand for the results of 2-step and 3-step calculation with NMTC/JAERI,respectively.
0 10 20 30 40 50 60 70 80
Neutron Energy (MeV)
Fig. 3. Neutron energy spectra for 67 MeVproton incidence on stopping-length Autarget. The dashed and the solid linesstand for the results of 2-step and 3-step calculation with NMTC/JAERI,respectively.
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JAERI-Revicw 95-019
8 . 3 Study of 7Li(p,n) Source Spectra and Neutron-inducedCharged-particle Emission Cross Sections at TIARA
Mamoru Baba, Tomohiko Iwasaki, Takehide Kiyosumi, Toshiya Sanami,Yasushi Nauchi, Naohiro Hirakawa, Takashi Nakamura:), Susumu Tanaka31,Hiroshi Nakashima41, Shin-ichiro Meigo41, Shun-ichi Tanaka41 and N.Nakao51
Dept.Nucl.Eng., Tohoku Univ., 2)CYRIC, Tohoku Univ.,3)JAERI Takasaki Establishment, 4)JAERI Tokai Establishment5)Institute of Nuclear Study, University of Tokyo
1. IntroductionAs a part of the study on accelerator shielding
and related nuclear data at the monoenergetic neuronsource facility of TIARA, we have been conductingmeasurements and analyses of the 7Li(p,n) sourceneutron spectrum and double-differential charged-particle emission, (n,z), cross sections for tens-MeVneutrons. The (n,z) cross section data are indispen-sable for evaluation of radiation damage andbiological effects of fast neutrons. However, ex-perimental data are very few and new data arerequired for the development of accelerator-basedneutron source for fusion reactor material test andnuclear-waste transmutation.
During the last year, we carried out l)newmeasurements of the 7Li(p,n) spectra at Ep=87 and 58MeV, 2)analyses of the C(n,z) data obtained in 1994,and 3)design of a wide-range charged-particle spec-trometer to extend the experiment to a-particles andlow energy protons.
2. Experiment1"1
For the experiments, we developed and applied aversatile charged-particle detector. The experimentalmethod has been described previously1'21.
The source spectra were measured by a proton-recoil-telescope (PRT) consisting of a polyethyleneradiator (0.5 or 1-mm-thick) and the telescopeemploying AE (900 mm2 PIPS) and E (2"-diam Nal)detectors. By adopting an "annular geometry", thepresent PRT achieves good energy resolution andsignal-to-background ratio with minimal loss ofdetection efficiency. In this geometry, the telescope isplaced on the neutron beam axis being shielded fromthe neutrons by a brass shadow-bar, 5.5-cm-diam and50-cm-long. Recoil protons from the polyethyleneradiator shaped to be "annular" are detected by thetelescope detector. The neutron spectrum data wereobtained down to -12 MeV with small uncertaintiesaround ±5 %.
The C(n,z) data were measured using the telescopeby replacing the polyethylene radiator with a carbon
plate (0.5-mm-thick). Measurements were done at 7angles from 7° to 120°. Measurements were doneusing the "annular geometry" at forward angles from7 to 20°, and conventional geometry at backwardangles, 30° to 120°, rotating the telescope around thesample.
Data were accumulated for three parameters, AE,E and TOF between AE and E for PRT using amulti-parameter pulse-height analyzer. For C(n,z)measurement, TOF between E and cyclotron RF wastaken in place of TOF between AE and E.
3. Data Analysis'21
First, particles of interest were selected from AEversus E display. The charged-particle spectra werecorrected for backgrounds, counting efficiency andcounting loss by inelastic-scattering in the detector.The efficiency was calculated with analytic andMonte-Carlo calculations. For analysis of PRT data,we adopted newly evaluated differential cross sectiondata for n-p scattering. The energy scale was det-ermined using linear response of Nal and the energyof the 7Li(p,n0|)
7Be neutrons determined with TOFmethod. Slight deviation from linear response wasalso taken into account.
4. Results and Discussion(1) 7Li(p,n) source spectmm
The results of the source spectra at Ep=87, and58 MeV are shown in Fig.l, together with previousresults at Ep=67 and 43 MeV. The source spectra arenot purely monoenergetic because of continuumneutrons due to breakup process. The lines in thefigure shows calculated phase-space distributionscorresponding to the three-body breakup reaction7Li(p,n3He)oc. The calculation describes the ex-periments consistently for all incident energies. (Thebump around 70 MeV in Ep=87 MeV data will bedue to some contamination and should be tracedfurther.) Therefore, this simple model can be used toestimate the low energy part of the continuumspectrum which is difficult to measure in spite of the
- 201 -
JAERI-Revicw 95-019
importance for the analysis of the experiments.The cross sections of peak neutron production, i.e.,
the 7Li(p,n01)7Be reaction, were deduced as shown in
Fig.2. The present results indicate the cross sectionsare nearly constant around 35 mb/sr in the tens MeVregion. The fraction of peak component, however,decreases with the increasing proton energy, and isless than 50 % above Ep=50 MeV.
[x109]
oa.CO3
[n/s
r/l
/iel
dN
eutr
on >
[x109]0
1
[x10']0
1
[x109]01
Neutron Energy [MeV] 100
Fig.l 7Li(p,n) source spectra.
Li(p,n)
40-
I 20u
n
so
*
B
~> 1 ~
hi iX PRESENT
T LLL
B CNL
•*• ORNL
t
i
• RUTHERFORD
A HARWELL
V MSC_
50Incident Proton Energy [MeV]
Fig.2 7Li(p,n01)7Be cross section.
100
2. C(n,z) reactionEnergy-angular doubly-differential cross section
data were obtained for protons, deuterons and tritonsfor 40 and 64 MeV neutrons, while the triton dataare not sufficient in counting statistics. An exampleof proton spectrum is shown in Fig.3. The spectraconsist of continuum components due to breakupprocess and structures due to low-lying states inresidual nuclei. It is noted that the spectra show verystrong angular dependencies and should be taken intoaccount in the evaluation of KERMA factors,radiation effects and so on.
The spectra were compared with thp phase-spacemodel, intra-nuclear cascade model (INCA)2' byBrenner, and QMD (quantum molecular dynamics) byS.Chiba et al.(JAERI)3'. The simple phase-space modeldid not provide a good description of the C(n,z) datain particular at 64 MeV in spite of its success in the7Li(p,n)7Be spectrum. INCA proved to describe theexperiment fairly well while it tends to underestimatethe experiment in the backward angles. In Fig.4,shown are comparisons of (n,p) data with QMDcalculation which is promising in view of wideapplicability in high energy region. QMD describesthe feature of the experimental data, but it should beimproved more for better description of structures andcomposite-particle (cluster) emission like d and a.
(3)Design of new telescopeAs shown in Figs.l and 3, the present telescope
has rather high threshold -12 MeV and can notmeasure a-particles because of large energy loss andbackgrounds due to surrounding air. Such a situationis similar for spectrometers used by other groups. Toextend the measurements, we are designing a newmulti-telescope system having much larger dynamicrange, better signal-to-background ratio as well ashigher efficiency. For the purpose, new spectrometerswill consist of a proportional AE counter and a BaF2
scintillator which enables particle-identification bypulse-shape analysis. They will be operated invacuum to reduce backgrounds and energy loss by anair. Pulse-height dynamic ranges will be extendedgreatly by incorporating updated particle-identificationscheme (pulse-shape and AE-E hybrid method). Nowthe test and construction are in progress.
5. Referencesl)M.Baba, T.Kiyosumi, T.Iwasaki, M.Yoshioka,
S.Matsuyama, N.Hirakawa, T.Nakamura, Su.Tanaka,R.Tanaka, H.Nakashima, S.Meigo, Sh.Tanaka;"Characterization and Application of 20-90 MeV7Li(p,n) Neutron Source at TIARA", Proc.Int.Conf.on Nuclear Data for Sci.Technol., (May, 1994,
- 2 0 2 -
JAERI-Review 95-019
Gatlinburg, USA) 90-92 (1995)2)T.Kiyosumi, M.Baba, T.Iwasaki, T.Sanami,
S.Matsuyama, N.Hirakawa, T.Nakamura, Su.Tanaka,H.Nakashima, S.Meigo, Sh.Tanaka; "Measurementof C(n,z) Double-differential Cross Section at 40,64 MeV" JAERI-Conf 95-008 193-196 (1995)
3)S.Chiba, K.Niita, T.Maruyama, T.Fukahori,H.Takada, A.Iwamoto; ibid., p.86 and privatecommunication
C(n,p) DDX, En=64 MeV
10'-1
10'
10"
,-2
8=7.2
I e =120.0
I I I I I I I U I20 40 60
Proton energy [MeV]
Fig.3 C(n,xp) emission spectra
(B)o This work (En=40.1 MeV, 9 =20)
_ QMD (En=40MeV, 8 -20)
i n__
3
co"•S (B) 3CD
oO
20 40Proton energy [MeV]
i i i r~o This work (En=64.5MeV,« =12.4)
En=64.5MaV. tfniO.O)
20 40 "6CfProton energy [MeV]
Fig.4 C(n,xp) spectra
- 203 -
JAERI-Review 95-019
8 . 4 Measurements of Neutron-induced Activation Cross Sections at
JAERI-Takasaki
M. Imamura, S. Shibata, T. Shibata, Y. Uwamino*, T. Nakamura2, E. Kim2, A. Konno2,
Susumu Tanaka3 and Shun-ichi Tanaka 4
Institute for Nuclear Study, University of Tokyo; Cyclotron Radioisotope Center, Tohoku
University2; JAERI- Takasaki3; JAERI- Tokai4
(# Present address: RIKEN)
IntroductionNeutrons with energies up to a few hundreds MeV
are most responsible for activation of materials in
thick target bombrdment, such as radioactivity
production due to secondary neutrons in accelerator
facilities. A 5-year research program started in 1992
aims at acquiring neutron-induced activation cross
sections as basic data for accelerator shielding studies
using the 40-90 MeV quasi-monoenergetic neutron
source facility "at TIARA-JAERI. For this purpose,
we have planned several irradiations between 40 and 90
McV.
In the preceding years we conducted 5 irradiation
experiments at 41 and 64 MeV2). During fiscal year
1994 we performed two activation experiments at
En=55 and 85 MeV.
ExperimentsThe 90-MeV AVF cyclotron of the TIARA
accelerator facility provides quasi- monoenergetic
neutron sources from 20 to 90 MeV using the (p,n)
reaction on a Li target. The neutron intensities (at
peak energy) are a few times 104 n/cm2/sec/u.A(proton)
at the irradiation position, located 4m downstream
from the Li target. The energy spreading of the peak
component is approximately 2 MeV. Experiments are
based on the activation method, viz., irradiations of
targets with the collimated neutron beam and
measurements of the produced y -ray radioactivities,
y-rays were measured with a Ge detector (relative
efficiency 36%) at TIARA. For some targets weak
y-rays were measured using the well-shielded Ge
detectors at INS. Radioactivities with half-lives of
lOmin. to 30 years were detemined for more than 50
reactions relevant to accelerator shielding studies.
Some Preliminary Results
Neutrons from the 7Li(p,n)7Be reaction have a lower
energy component with a broad and almost continuous
spectrum in addition to the peak component. To
calculate activation cross sections, correction is
necessary for the contribution from the lower energy
part of neutrons. Therefore cross section data for the
lower energy must be also known. Since the
experiments have been performed so far at only 4
energies with rather coarse energy intervals and we
have almost no published experimental cross section
data above 40 MeV, we have tentatively estimated
cross sections by assuming the shape of the theoretical
excitation functions or by using rather intuitive
interpolations of cross sections for lower energies.
Below, we show several examples of the preliminary
results obtained.2a>Bi(n,xn)2"'"'Bi reactions (Fig.l)
Since the reactions have large cross sections with
threshold energies increasing in steps of 8-10 MeV and
the radioactive products have proper half-lives of 30
min. to 30 years for x=3-10, the reactions are ideal for
neutron flux evaluation between 20 and ca.100 MeV.
By irradiating Bi monitor targets the leakage neutron
spectrum can be evaluated if activation cross sections
are known. Theoretical calculations for these reaction
cross sections have been given in ENDF/B-VI. The
ENDF/B-VI evaluation3' recently reported reproduce
fairly well the TIARA experiment data so far obtained
as well as the INS experiment data below 40 MeV4'.12C(n,2n)"C, 12C(n,x)7Be, and °Al(n jc)°Na
reactions
These reactions have been considered useful for
monitoring high energy neutrons. However the
experimental results show deviations from theoretical
estimations given in the ENDF/B-VI. The12C(n,2n)nC
- 2 0 4 -
JAERI-Review 95-019
reaction seems to have a broad peak of ca. 20 mb at
around 40-60 MeV(Fig.2). The cross section decreases
slightly with energies up to 85 MeV or remains
almost constant. The "Alfox^Na reaction has a
excitation function which is typical in compound
nucleus formation. The peak cross section is about 20
mb at around 40 MeV , which is about a factor of two
lower than the ENDF/B-VI estimation. In the case of
the 12C(n,x)7Be reaction, the cross section goes up
with increasing energies, showing a spallation-like
excitation function(Fig.2).
References
1) T. Nakamura et al., Proc. of the 8th Int'l Conf. on
Radiation Shielding(Arlington, U.S.A., Apr.1994)
p. 264.
2) M. Imamura et al., TIARA Annual Report 1993
3) ENDF/B-VI, NNDC, BNL(1993)
4) A.Konno et al. INS Annal Report 1993, p.21.
100
10 20 4 0 50 60 70
energy, MeV
8 0 00 100
Fig.2. Experimental production cross sections forn C and 7Be from carbon. The data below 40
MeV are from Uno et al.(1993, unbpublishcd
data).
10
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Bi(n,2n),BNL
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(n,6n),ENDF/VI
(n,7n),ENDF/VI
(n,8n),ENDF/VI
(n,9n),ENDF/VI
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• (n,5n),INS,TIARA
n (n,6n),TIARA
• (n,7n),TlARA
o (n,8n),TIARA
10 20 30 40 50 60 70 80 90
neutron energy, MeV100
Fig.l. Preliminary results for the reactions. The errors are not indicated in the figure.
- 205 -
JAERI-Rcview 95-019
8 . 5 Measurements and Analyses on Neutrons Transmitted Through Iron andConcrete Shields in Intermediate Enery Region
H. Nakashima1, N. Nakao2, S. Tanaka3, T. Nakamura4, K. Shin5, S. Tanaka6,S. Sakamoto1, H. Takada1, S. Meigo1, Y. Nakane1 and M. Baba7
1. Tokai Establishment, Japan Atomic Energy Research Institute2. Institute for Nuclear Study, University of Tokyo3. Planing Office, Japan Atomic Energy Research Institute4. Cyclotron and Radioisotope Center, Tohoku University5. Department of Nuclear Engineering, Kyoto University6. Takasaki Establishment, Japan Atomic Energy Research Institute7. Department of Nuclear Engineering, Tohoku University
Introduction
As a part of a research program running asa cooperative project between JAERI andseveral universities to acquire the crosssection and shield data for neutron in theintermediate energy region, a series ofaccelerator shielding experiments has beencarried out using a p-7Li quasi-mono-energetic neutron source at AVF cyclotronin TIARA. In this study, neutron spectratransmitted through iron and concreteshields were measured to provide thebenchmark data, and analyzed by someshielding design methods to estimate thevalidity of the nuclear data and to confirmthe applicability of neutron transport codes.
Experiment
Neutron spectra transmitted through ironand concrete shields were measured usingthe monoenergetic neutron source settled atLC beam line in the AVF cyclotron facilityas shown in Fig. 1. Neutrons generated by43- and 67-MeV protons on the 7Li targetof 2-MeV-loss-thickness passed throughthe iron collimator of 11 cm in diameterand 225 cm long. After going through anadditional collimator of 11 cm diameter andup to 80 cm long, neutrons bombarded theiron and concrete shields of 120 cm width,120 cm height and 20 to 200 cm thickness.
The pulse height distributions weremeasured by a 5"<j> x 5" BC501A liquid
Proton
Li Target 9
Monitor
Detector
Fig. 1 Vertical view of experimental arrangement.
- 2 0 6 -
JAERI-Review 95-019
scintillation detector set just behind theshields on the beam axis and at 20 cm and40 cm distance off the beam axis. Aftereliminating the component of pulse heightsdue to y-rays, neutron spectra wereobtained by an unfolding code FERDOU^with the measured response matrix. Sourceneutron intensity monitors, a Faraday cupand fission chambers, which were calibratedto the absolute value of neutron sourceintensity measured by a proton-recoiltelescope2), have been operated during theexperiments.
Calculation
The transmitted neutron spectra werecalculated using the two-dimensionaldiscrete ordinates code DOT3.53) and theMonte Carlo code MORSE-CG4) with theDLC119/HILO865) group constant sets up to400 MeV having Ps Legendre expansions.The Monte Carlo code HETC-KFA26) usedin the high energy particle transportcalculation was also applied in the analysis.The source neutron spectrum measured bythe TOF method using the BC501A detectorwas used, which was normalized to theabsolute value by the measurement usingthe proton-recoil telescope. In MORSE andHETC calculations the source neutrons wereassumed to be emitted only in a very shapecone of 5.94 x 10"4 sr along the beam line.In DOT3.5 calculation the source neutronswere assumed as a point isotropic sourcelocated at the position of the Li target, andthe first collision source calculated by theGRTUNCLE code75 was utilized to removeray effects.
As a geometry in MORSE and HETCcalculations the iron and concrete shieldswere located at 4 m away from the target,and the concrete walls surrounding theshield materials were considered to be 40cm thick. For DOT3.5 calculation theupper side of the beam axis in Fig. 1 wasapproximated as a two-dimensional geome-try.
Results and Discussion
The spectra calculated by the MORSE andDOT3.5 codes are compared with the mea-sured ones behind the 70 cm thick iron and100 cm thick concrete shields on the beamaxis at the incident proton energy of 67MeV, as examples, in Figs. 2 and 3,respectively. The calculated results agreewith the measurements within the error.This confirms that elastic and inelasticscattering cross sections are adequate, wherethe HILO86 library was calculated by theHETC code for inelastic scattering and theoptical model adjusted to the experimentaldata for elastic scattering. As is shown inFig. 4, however, the MORSE calculationsunderestimate the measurement at the off-center position, because the P5 Legendreexpansion is too rough to reproduce theangular distribution of elastic scatteringhaving strongly forward-scattering distribu-tion. It is suggested, therefore, that a largernumber of Legendre expansion order ingroup constant sets or the cross sectionlibrary of double-differential type should beused in order to apply the shielding designcodes for fission and fusion reactors limitedto the energy region up to 20 MeV to thehigh and intermediate energy acceleratorshielding design.
The original HETC calculations withouta built-in elastic scattering option, whichmeans to use only the intranuclear-cascade-evaporation model, overestimate themeasured spectra as shown in Figs. 2 and 3.The HETC calculations with the elasticscattering option utilizing the same data asthe elastic cross sections in the HILO86library still overestimate the measurementsby about a factor of 2. As shown in Fig. 4,moreover, the HETC calculation largelyunderestimates the measurement, and doesnot reproduce the neutron peak due toelastic scattering. This result presents thatthe angular distribution of elastic scatteringis inadequately treated in the code, thoughthe distribution is expanded by the Bessel
- 2 0 7 -
JAERI-Review 95-019
function which is more suitable thanLegendre function to express stronglyforward-scattering distribution. Thus, itimplies that the contribution of elasticscattering is very important in this energyregion and the handling of elastic scatteringreaction in the HETC code should bemodified.
References1) K. Shin, Y. Uwamino and T. Hyodo,
Nucl. Technol., 53, 78 (1981)2) M. Baba, et al., JAERI-M 94-019, 200
(1994)3) W.A. Rhoades and F.R. Mynatt,
ORNI/TM-4280 (1979).4) G.R. Straker, P.N. Stevens, D.C. Irving
and V.R. Cain, ORNL-4585 (1970)5) R.G. Alsmiller, Jr., J.M. Barnes and J.D.
Drischler, ORNL/TM-9801 (1986).6) P. Cloth, et al., FA-IRE-E AN/12/88
(1988).7) R.A. Liltie, R.G. Alsmiller, Jr. and J.T.
Mihalczo, Nucl. Technol., 43, 373(1979).
10
Neutron Energy (eV)
Fig. 2 Comparison of measured andcalculated spectra of neutron transmittedthrough the concrete shield of 100 cm
thick on the beam axis at proton energy of67 MeV.
«
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HETC with clastic
T J J HD-In J
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107 10°Neutron Energy (eV)
Fig. 3 Comparison of measured andcalculated spectra of neutron transmitted
through the iron shield of 70 cm thick onthe axis at proton energy of 67 MeV.
10"
10"
DOT3.S
MORSE
IIETC wilh clastic
• I I I I
io7 io 3
Neutron Energy (eV)
Fig. 4 Comparison of measured andcalculated spectra of neutron transmittedthrough the iron shield of 70 cm thick atoff-center of 20 cm at proton energy of
67 MeV.
- 2 0 8 -
JAERI-Review 95-019
9. Accelerator Technology
9.1 Development of Visual Beam Adjustment Method for Cyclotron
T.Agematu, K.Arakawa, S.Okumura, Y.Nakamura, W.Yokota,
T.Nara and I.Ishibori 211
9.2 Beam Diagnostic Development for the Cyclotron
S.Okumura, I.Ishibori, M.Fukuda, T.Agematu, W.Yokota,
Y.Nakamura, T.Nara and K.Arakawa 214
9.3 Present Status and Beam Acceleration Tests on Cyclotron
K.Arakawa, Y.Nak£.rt>ura, W.Yokota, T.Nara, T.Agematu,
S.Okumura, I.Ishibori and M.Fukuda 217
9.4 First Operation of 18-GHz ECR Ion Source
W.Yokota, Y.Wu, Y.Saitoh, Y.Ishii, T.Nara and K.Arakawa 221
9.5 Temperature Increase of Power Cable Assembly Laid in Sleeve
through Shielding Concrete at Cyclotron Facility
Y.Nakamura 223
9.6 Development of High Energy Single Ion Hit System Combined
with Heavy Ion Microbeam Apparatus
T.Kamiya, T.Suda and T.Hirao 226
9.7 2MeV Submicron Microbeam Focusing
T.Kamiya and T.Suda 229
9.8 Fluence Uniformity Measurement of Two-dimensionally Scanned
Radiation Field of 400kV Ion Implanter
K.Mizuhashi, S.Bunnak, K.Ohkoshi, S.Tajima and R.Tanaka 232
9.9 Acceleration of Cluster Ions by 3MV Tandem
Y.Saitoh, S.Tajima, I.Takada, K.Mizuhashi, S.Uno, K.Okoshi,
Y.Nakajima and Y.Ishii 234
9.10 Energy Calibration of Single-ended Accelerator
Y.Ishii, S.Tajima, I.Takada, K.Mizuhashi, Y.Saitoh, S.Uno,
K.Okoshi, T.Kamiya and R.Tanaka 236
9.11 Preliminary Study of Ultra Fine Microbeam (II )
Y.Ishii, R.Tanaka and A.Isoya 238
9.12 Development of a High-precision Beam Profile Monitor
H.Kobayashi, T.Kurihara, T.Urano, T.Suwada, R.Tanaka,
S.Okada, S.Masuno and Y.Aoki 240
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JAERI-Review 95-019
9 . 1 Development of Visual Beam Adjustment Method forCyclotron
Takashi AGEMATSU, Kazuo ARAKAWA, Susumu OKUMURA,Yoshiteru NAKAMURA, Watalu YOKOTA, Takayuki NARA andIkuo ISHIBORIAdvanced Radiation Technology Center, JAERI
IntroductionA cyclotron design requires a large
number of physical theories, calculation codesand analysis of the beam trajectory. Thesecodes and analyzed results have not been usedin actual operation. For a new cyclotroncontrol technique, we have developed acomputer-based visual assistance system [1]for the JAERI AVF cyclotron [2] by using theabove codes. To examine the reliability ofthis system, the result of the simulation wascompared with that of the actual operation.
Human interfaces
The visual assistance system providesthree functions of human interfaces for beamparameter adjustment; (a) Beam trajectory israpidly calculated and graphically displayedwhenever the operators change the cyclotronparameters, (b) Feasible setting regions(FSRs) of the parameters which satisfy beamacceptance criteria of the cyclotron's areindicated, (c) Search traces which arehistorical visual maps of beam current valuesrepresented by various colored dots, aresuperimposed on the FSRs. The system hasbeen applied to three blocks of the cyclotron:the axial injection, the central region and theextraction.
Evaluation of simulation
Axial injection block
The axial injection block is a regionbetween the bottom of the cyclotron yoke andthe inflector. There are four Glaser lenses(GLs) with adjustable focal lengths. Thebeam is led into the cyclotron by adjustingthese lenses through a small gap of theinflector entrance. The FSRs are limited
mainly by the geometry of the inflectorentrance.
We have compared the human interfaceswith the results of actual operation in the
accelerating conditions of H+ 45 MeV(harmonic mode 1: h=l), H+ 10 MeV (h=2)and 40Ar8+ 175 MeV (h=3). It was indicatedthat there was a discrepancy between thesimulated FSRs and the search traces obtainedin actual operation. The simulated beamtrajectories deviate from the search trace justafter last GL. This deviation is caused by theleakage of magnetic field from the mainmagnet.
Central region blockThe central region block is followed by
the axial injection block. The first turn of thebeam trajectory after the inflector isdetermined in this block. The adjustableparameters in this region are dee voltages,trim coil currents and the phase of beambuncher voltage. These parameters areadjusted so that the beam passes through twosets of phase slits. The beam trajectory andFSRs are calculated as functions of theseparameters and magnetic and electric fielddata. The FSRs are limited mainly by thegeometrical condition of the phase slits.
To evaluate the simulation model of beamtrajectory, we have compared the position ofactual beam trajectory with the simulatedbeam one. The intensities of magnetic bumpfield produced by circular trimming coils littleinfluence the position of actual beamtrajectory. The beam phase dependency onthe beam position could not be measuredbecause the beam intensities were decreaseddrastically in changing phase of the beambuncher.
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JAERl-Review 95-019
Position Measurcinq Trajectory
_a_OEF EXIT
-30
Rat nun probe
30BA
R at deflector probe
317.3
R s i mag. cfcan. probe ptira j
Ene»gy: 10.74 iteV(-6.WS.)
-4.3
R
Fig. 1 Beam trajectory simulation at the extraction block.The spiral beam trajectory is shown as a stretched line in this diagram.
Extraction block
The beam in the final turn is led into thedeflector and the magnetic channel, deflectedfrom the circular orbit, and finally extractedfrom the cyclotron. In this block, the systemsimulates the deflected beam trajectory. Atthe first step, the beam trajectory entering thedeflector is calculated on the basis of themagnetic field data and two beam positionsdetected by the main and the deflector probes.At the second step, the beam trajectory in thedeflector and the magnetic channel issimulated on the basis of the deflectorposition, the deflecting field and the magneticchannel field. The FSRs were calculated asfunctions of the above parameters, and theclearance of the deflector and the magneticchannel.
An example of simulated beam trajectories
for nominally 20 MeV of 4He+2 ion is shownin Fig. 1. We have executed simulations toget the beam trajectories, passing through theexit of the cyclotron, for several beamenergies. The most suitable energy for thetrajectory in actual operation condition is in arange from 18.98 to 19.06 MeV. On theother hand, the beam energy is evaluated at19.10 MeV (-4.5%) from the magnetic fieldof the analyzing magnet after the cyclotron.The simulated beam energy is in agreementwith the beam energy measured by using theanalyzing magnet.
To evaluate the trajectory model of thebeam extraction from the cyclotron, we havediscussed how to estimate the beam energy inthe final turn. Inside the cyclotron, threeradial probes were installed to measure thebeam intensity distribution as shown in Fig.2. A main radial probe covers all theacceleration range of radius from 40 mm to1190 mm. A deflector probe, provides thebeam intensity before the deflector. Amagnetic channel probe provides the beamintensity after the passing through thedeflector. We have tried to estimate the beamenergy by following techniques.
Magneticchannel
probe
Deflectorprobe
Main probe
Fig. 2 Location of three beam probes.
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JAERI-Review 95-019
3- 2
ooXoLU
o - ,LU
UJ
Q)O
I
0 -
- 4 -
T5 " 6 •—
5LJJ
- 8
1
-
-
_ 0/
1 1
0
/
1 1
1
n /
/o
1
1
O,
f
1
/ ~
O
—
—
- 6 0 - 5 0 - 4 0 - 3 0 - 2 0 - 1 0 0 10
Beam position of extraction radius [mtv]
Fig. 3 Energy evaluation by orbit radius method.E: energy evaluated from the simulated
trajectories passing through the exit of thecyclotron and the analyzing magnet.
Eo: nominal energy
1) Orbit radius method; The beamposition is measured by the main radial probe.The energy (E) is evaluated from thesimulated trajectories passing through the exitof the cyclotron and the analyzing magnet.As shown in Fig. 3, the beam energiesdepend on the beam positions of the final turntrajectory.
2) Three point method; The beampositions in the three points were measuredby the main probe, the deflector probe and themagnetic channel probe, respectively. Thebeam energy (E1) is estimated from simulatedbeam trajectory passing through the abovethree points.
Figure 4 shows the relation between theenergy E and the estimated energy E'. Thesolid line shows the experimentally estimatedenergy and the dot line shows the ideal one.The result of estimations for beam energy,data has error within ±2% from linearapproximation formula.
Upgrade the system
Application of the system has been limitedto several accelerating conditions of ionbeams. Because at the early time ofdevelopment, it is not need to executesimulations for all the available particles andenergies. At present, this system has been
- 8 - 6 - 4 - 2 0 2
Estimated energy difference E'-Eo / Eo x 100 [%]
Fig. 4 Energy estimation by three point method.
E': estimated energy from three point methodEo: nominal energy
upgraded to simulate the beam trajectories andFSRs in all accelerating beam conditions forthe JAERIAVF cyclotron. We can obtain theoperating parameters for new ion accelerationtests.
Future activity
Precise comparison of the simulated beamtrajectory and the actual beam trajectory isplanned for the extraction block in newaccelerating conditions. The extracted beamenergy will be measured accurately by othermethods, such as kinematics and TOFmethod. It is expected that the result will befed back to improve the system. We willexpand this technique to the beam transportsystem.
References[1] T.Okamura and T.Murakami, "An Operator
Assistance System for Beam Adjustment of aCyclotron", IEEE Trans, on Nucl. Sci., Vol.39,No. 1, pp. 13-20(1992).
[2] K.Arakawa, Y.Nakamura, W.Yokota, M.Fukuda,T.Nara, T.Agematsu, S.Okumura, I.Ishibori,T.Karasawa and R.Tanaka "Construction and FirstYear's Operation of the JAERI AVF Cyclotron",Proc. 13th Int. Conf. on Cyclotron and theirApplications, Vancouver, Canada, pp.119-122(1992).
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JAERl-Review 95-019
9 • 2 Beam Diagnostic Development for the Cyclotron
Susumu OKUMURA, Tkuo ISHIBORI, Mitsuhiro FUKUDA,Takashi AGEMATSU, Watalu YOKOTA, Yoshiteru NAKAMURA,Takayuki NARA and Kazuo ARAKAWAAdvanced Radiation Technology Center, JAERI
Introduction
The JAERI cyclotron has been mainly usedfor materials science experiments. Largesamples of various materials up to 100 x100 mm2 arc irradiated with high-energyhigh-intcnsuty ion beams using the beamscanning and defocusing methods. The flu-ence uniformity of less than ±10 % is usuallyrequired within the irradiation area.
Therefore, monitoring the distribution onthe irradiation area is needed for tuning theparameters of the beam scanning magnetsand other beam transport devices. Cellulosetriacetate (CTA) film dosimeter has been usedfor profiling the fluence distribution, butcannot be applied to real-time measurement.For efficient tuning to the required uniform-ity, two-dimensional position sensitive detec-tors have been applied to the real-time meas-urement of the distribution.
The beam of the cyclotron is pulsed at theequivalent frequency as the RF of the cyclo-tron. The pulsed beam thinned out by thebeam chopping system at various intervals ( 1us ~ 1 ms ) is mainly used for time-of-flightexperiments and time-resolved analyses.
The timing information on the beampulse is needed for parameter tuning in thechopping system to provide required condi-tion of the beam pulse. A trigger signal of thebeam pulse allows higher time-resolution ex-periments than a signal originated from theRF because of a fluctuation of phase dif-fernce between the beam pulse and the RF.We have a plan in which a beam energy willbe measured by a time-of-flight method withfast timing counters for calibration of ananalyzing magnet. For these purpose, a beampulse monitor, detecting beam pulses withhigh time resolution and high sensitivity, hasbeen constructed and tested in 45 MeV pro-ton and 260 MeV neon beams.
Measurement of fluence distribution
Two kinds of position sensitive detectors havebeen applied to measurement of the fluencedistribution on real-time with a spacial reso-lution of 1-2 mm. Electrodes of these detec-tors consist of strips connected with theneighbor one by chip resistors. The positionof the incident particle is detected by the re-sistive charge division method.
One of the position sensitive detectors is aparallel plate avalanche counter(PPAC) fordetecting heavy ion beams. We have con-structed a PPAC with a sensitive area of120x120 mm" and eighty strips with eachwidth and interval of 1.25 mm and 1.5 mm,respectively!!], and started to test it [2J. Thespecification of the PPAC is shown in Ref [1].
The other one is a silicon strip detec-tor(SSD) for detecting light ion beams. Sincethe signal gain of light ion beams in thePPAC is not enough, a silicon strip detec-tor(SSD), with higher-density detection vol-ume than the PPAC, has been applied forlight ion beams.
The SSD (S2461-01 Hamamatsu Photon-ics Ltd.) has a thickness of 300 um and a sen-sitive area of 48x48 mm", and is used at anapplied voltage of +75V. The SSD consists of48 strip electrodes, with each width and pitchof 0.9 mm and 1 mm, respectively. The SSDis mounted on a printed circuit board with thesignal leads for each strip electrode. For thespecific pattern of the leads, only a half of theelectrodes are used and a pitch of the elec-trode is 2 mm. The leads are connected withthe neighbor ones by chip resistances. A cou-ple of SSD's were used for two-dimentionalposition detection.
Since the signals from the PPAC and theSSD are processed by amplifiers within ashaping time of few us for pulse height analy-sis, the frequency of particle incidence is re-stricted within 1000 particles per second. Foradjustment of the beam intensity to the ac-ceptable counting rate of the detectors, thebeam attenuator[3] is used to reduce thebeam intensity by a factor of 1 to 10'9.
- 2 1 4 -
JAERI-Review 95-019
[•"-'..I I....::X:.....{^....J.
• ;„••»' ..'•#": ^
| • • - • • ; - . ..'m
i. • . .'»•- -«.>"-»
\ •- '.i'- •;- »I ;•"" • ; *'" *
- 1 ' 1 -• . . . . .
1 1 1-
m >#'
- . * • • * •
• m
1 L
I . . .
*
' * '
. « ,
M
.«.
. . .4 . . :
•
•
. , , . 1 .
*
*
r
!
[I
i
I
J!
(a) X
Fig. 1. An example of fluence distribution measured with PPAC for 175 MeV 40Ar8+. (a)Two-dimensional distribution. (b)One-dimensional distribution in the X direction. (c)One-dimensional distribution in the Y direction.
01000
§ 500
a0
— 1 1 1
' B FWHM I
'M- , -M
( ' ' ) '10 m m 'Jk
jftrr M1 i J M ^ U -
5 31 | 1 1 -
-
(b) .X
(a) X
Fig. 2. An example of fluence distribution measured with SSD for 10 MeV H+. (a)Two-dimensional distribution. (b)One-dimensional distribution in the X direction. (^One-dimensional distribution in the Y direction.
The tests of these detectors have been car-ried out for a large area irradiation with thescanning magnets. Aluminum collimatorswith two-dimensionally arranged 9x9 holes of0.5 mm diameter at intervals of 10 mm wasset in front of the detector for measurementof the positional resolution.
Figure 1 shows an example of fluence dis-tribution measured with the PPAC for 175
MeV ^Ar8"1", which corresponds to the patternof the collimator. The positional resolution(FWHM) of the X direction is 2.7 mm and theY direction 2.5 mm. Since the resolutions ofthe PPAC are worse than the expected ones of1.5 mm equal to the pitch of the strips, im-provement is needed.
Figure 2 shows the fluence distributionmeasured by the SSD for 10 MeV H+, which
- 215 -
JAERI-Rcview 95-019
corresponds to the partial pattern of the col-limator. The positional resolution (FWHM) ofthe X direction is 2.3 mm and the Y directionL.7 mm. The count differences of the peaks,especially in the Y direction, seemes to becaused by the way of the signal process.
Detection of beam pulse
For beam current of more than a few nA,non-destructive methods, such as capacitivepick-up probes, can be applied to beam pulsedetection. Since beam pulse experiments fre-quently require a low beam current of lessthan nA, high sensitive detection method isneeded.
The pulse beam has an interval of 45 to94 ns, which depends on the RF frequency,and a pulse width is a few ns. Therefore, apulse beam measurement with a time resolu-tion of less than 1 ns is required for tuningthe beam pulse and producing the triggersignal for experiments without disturbing thebeam quality.
A pulsed beam detection system has beenconstructed using a micro channel plate(MCP), a fast timing detector for chargedparticles and photons. The MCP amplifiessecondary electrons and photons emittedfrom a inserted target when a beam pulsepasses through the detector [4], and providesa fast timing signal.
The system consists of an assemble typeMCP (F4655-10, Hamamatsu photonics Ltd.),seven sets of electrodes spaced by insulatorrods(AhO3) and targets for the secondaryelectron emission. The secondary electronsemitted from the target are guided onto theMCP through an electrostatic field biased upto -10 kV. We have two targets: a tungstenwire 0.3 mm in diameter and a aluminum foil3 (xm thick and 5 mm wide. The foil is mainlyused for detection of light ion beams. Thetargets are stretched in parallel with the sur-face of the MCP and positioned at differentdistances from the MCP for independent use.The position of the foil is shifted horizontallyfrom that of the wire not to disturb the secon-dary electrons from the wire. The entranceface of the MCP, and the surface of the wireand the foil were evaporated with Csl to opti-mize the emission of the secondary electrons[5]. The system is driven by a stepping motorto adjust the relative position of target to thewire. The system allows almost non-destructive detection of the beam pulse by
selecting the appropriate target and adjustingthe target position to keep the passing beamin high quality.
The tests of the system have been carriedout using 175 MeV 40Ar8+ and 45, 70 MeVH+ beams. Figure 3 shows an example of thetime spectra measured by a time-to-amplitudeconverter using the signal from the MCP as astart signal and the RF signal with a dividedrate as a stop signal. The width of the pulsedbeam is 2.3 ns in FWHM.
5000
4000
- 3000
O 2000
1000
65.7nS-
FWHM = 2.3nS
200 400 600 800TAC (ch)
1000 1200
Fig. 3. Time spectrum measured for 175MeV 40 Ar 8+. The target is a 3 [im thickaluminum foil. The collection voltage forsecondary electrons is -7.66 kV.
References
[1] S.Okumura et al., "Development of Par-allel Plate Avalanche Counter for Flu-ence-Rate Measurement", TIARA AnnualReport, Vol.2, 198-199 (1992).
[2] S.Okumura et al., "Measurements ofBeam Characteristics for AVF Cyclotron"TIARA Annual Report, Vol.3, 202-204(1993).
[3] S.Okumura et al., "Development of BeamAttenuator", TIARA Annual Report,Vol.2, 196-197 (1992).
[4] M.Kase et al., "Development of a BeamPhase Monitor with a Micro-ChannelPlate for the RIKEN Ring Cyclotron", the9th Symp. on Accel. Sci. and Tech.,Tsukuba, Japan, 474-476 (1993).
[5] H.L.Seifert et al., "Increased SecondaryElectron Yield from Thin Csl Coatings",Nucl. lnstr. and Meth., A292, 533-534(1990).
- 2 1 6 -
JAERI-Revicw 95-019
9 . 3 Present Status and Beam Acceleration Tests on Cyclotron
Kazuo ARAKAWA, Yoshiteru NAKAMURA, Watalu YOKOTA, TakayukiNARA, Takashi AGEMATSU, Susumu OKUMURA , Ikuo ISHIBORI andMitsuhiro FUKUDA.Advanced Radiation Technology Center, JAERI
Introduction
The operation of the AVF cyclotron forexperiment was started from January 1992 indaily operation mode on a trial base. Theweekly continuous operation was started fromSeptember 16 1992. The total operationtimes amounted to 10000 hours in February1995. The cyclotron [1][2] is mainly usedfor R&D in materials science and otherirradiation purposes. These applications ofthe cyclotron require that many kinds of lightand heavy ions can be accelerated in a widerange of energies. To meet the requirement,continuing efforts have been made on newbeam development, improvement of beamextraction and transmission, etc.
Present status
The AVF cyclotron was smoothly operatedfor experimental utilization in FY 1994. Thebeam time for experiments was 2555 hours inFY 1994. Twenty-five ion species wereprovided for experiments.
A baffle slit system at the extraction hole ofthe acceleration chamber in the cyclotron wasreplaced by remote driving type one for easycontrol the slit width as shown in Fig.l.We added a plate to this system in order tomeasure the total beam currents. To measurethe beam profile of accelerated beams in thecyclotron,
Fig. 1. Photograph of the baffle slit system.
a single-wire profile monitor was installedjust after the gradient corrector.
The accumulation of induced radioactivityin the acceleration chamber is making it moredifficult to conduct maintenance work insidethe cyclotron. The strongest source ofradiation is usually the electrostatic deflector(20 mSv/h at surface of septum electrode),the septum electrodes of the deflector werereplaced by new ones. Furthermore, weprepared a new set of deflectors for rapidreplacement in case of trouble.
For protection against radiation hazards, itwill be necessary to replace some of thestrongly activated parts, such as main probe-head, magnetic channel, and magnetic channelprobe-head.
We had the following iroublc; (1) adestruction of the rotor and sialor for theturbo-molecular pump in the beam transportline after the cyclotron, (2) a trouble of air leakfor the multi-cusp ion source, and (3) abreakdown of the (i-wave power for theklystron by discharge of high voltage in theECR ion source.
Beam development
(1) New beam accelerationThe beam acceleration tests have been
conducted for 60 and 90 MeV H+, 350 MeV2 0 Ne 8 + and 160 MeV 1 6 O 6 + . Protons aregenerated by the multi-cusp ion source, andother ions by the ECR ion source. The resultsof the beam acceleration test are summarized
in Table 1. The 60 MeV H+ beam current islimited within 5.0 uA for the present to avoiddamage of the machine parts. The extractedbeam current for 2 0Ne8 + and 16Q6+ i o n s are
- 2 1 7 -
JAERI-Revicw 95-019
1.5 |iA and 1.9 |iA (electrical ampere)respectively.
(2) Extraction current and transmissionParticles accelerated and extracted so far are
listed in Table 1. The extraction efficiency isdefined by the ratio of the beam currentmeasured with the main probe at r=900 mm tothat with the Faraday cup (FC) just aftercyclotron. The average extraction efficienciesfor harmonic 1, 2 and 3 are 57.7 %, 66.5 %and 53.2 %, respectively. .
The overall transmission efficiency isdefined by the ratio of the beam current withthe FC just after analyzing magnet at theinjection line to that with FC just aftercyclotron. The average transmissionefficiencies for harmonic 1, 2 and 3 are 13.5%, 16.7 % and 11.0 %, respectively. Thebest extraction and overall transmissionefficiency was 86 % for 330 MeV 40Ar' 1 +
and 27 % for 10 MeV H+, respectively. Themaximum beam currents of heavy ions suchas Ne, Ar and Kr mainly depend on the abilityof the ECR ion source.
(3) Single pulse extractionThe beam chopping system[3] consists of a
pulse voltage chopper (P-chopper) and asinusoidal voltage chopper (S-chopper). TheP-chopper was made to chop DC beams fromthe ion sources into pulse beam in theinjection line. The S-chopper was made toextract a single beam pulse after the exit of thecyclotron. The single pulse was successfullyextracted for 220 MeV 1 2C5 + ion using thechopping system.
(4) ECR ion sourceThe ECR ion sources are presently used
for two purposes; (1) injection of highlycharged ion beams into the AVF cyclotron,(2) study and development of ECR ion sourcefor high charged ion beams of gaseous andsolid elements. A new gas feed line wasadded for isotope gases which are veryexpensive. Tubes from gas cylinders were
connected to the common line, may be less
than 3 cm3 . It is used for 36Ar and 129Xe.Test generation of metallic ions are carriedout by using insertion of ceramic rods intoECR plasma. Ni ions are generated fromNiO and Cr ions from CrSi2 and Cr2O3.Though the insertion depth was notoptimized, the maximum charge states are 17for Ni and 15 for Cr, and ion beam currentsare enough for acceleration by the cyclotron asshown in Table 2. These materials haveproper vapor pressures for metallic ions [4],and the beam stability were good.
Table 2.
Material
Beamcurrents
(e|iA)
Extracted beam currentroads.
.NiO58Ni
17+16+15+13+12+10+9+8+
0.51.02.83.84.04.42.11.2
CrSi25 2Cr15+14+12+11+9+8+
0.51.84.05.85.24.5
for ceramic
Cr2O352Cr15+14+12+11+9+8+
0.81.21.92.71.5
0.9
(5) Pulse beam detection systemThe pulsed beam experiments require non-
destructive methods to monitor the beamduring the experimental time and highsensitivity to a wide variety of beams fromproton to heavy ions in wide ranges ofacceleration energy and beam intensity. Forthese reasons, we have developed a highlysensitive beam pulse detection system using amicro channel plate (MCP) with a high-signalgain and time-resolution. The pulsed beamcan be detected by secondary electrons emittedfrom a thin target when the beam passingthrough it. The system have been tested by
using a 175 MeV 40Ar8+, 45 and 70 MeV H+.The details of this system is reported in aseparate paragraph in this chapter[5].
(6) Measurement of fluence distribution
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JAERI-Revicw 95-019
The fluence distribution over the irradiatedarea was measured by CTA dosimeters basedon the radiation induced optical densitychange of the dosimeter film. However, thismethod does not give fluence distribution inreal time. To monitor two-dimensionalfluence distribution in real time, we aredeveloping two types of detectors: one is aparallel plate avalanche counter (PPAC) forheavy ions, and the other is a silicon stripdetector (SSD) for light ions. The two-dimensional fluence distributions under beamirradiation were successfully measured byPPAC and SSD. The details of this system isreported in a separate paragraph in thischapter [5].
(7) Computer-based visual assistance systemWe have developed a computer-based
visual beam adjustment method forcyclotrons[6]. This method provides a CRT-display of simulated beam trajectories,feasible setting regions (FSRs) of operatingparameters and historical maps of beamcurrent value. As a result of the test on theactual operation of the JAERI AVF cyclotron,it turned out that the simulation approximatesactual beam trajectories well and FSRs arehelpful to operations for the axial injection,the central region and the extraction. Precisecomparison of the simulated and the actualbeam trajectory is try under variousaccelerating conditions. We are upgradingthe system to execute simulations for all theavailable particles and energies.
References[1] K.Arakawa, Y.Nakamura, W.Yokota,
M.Fukuda, T.Nara, T.Agematsu,S.Okumura, I.Ishibori, T.Karasawa,R.Tanaka, A.Shimizu, T.Tachikawa,Y.Hayashi, K.Ishii and T.Satoh, Proc.13th Int. Conf. on Cyclotron and TheirApplications, Vancouver, Canada, pp.119-122 (1992).
[2] K.Arakawa, Y.Nakamura, W.Yokota,M.Fukuda, T.Nara, T.Agematsu,
S.Okumura and I.Ishibori, Proc. 9thSympo. on Accele. Sci. and Tech.,Tsukuba, Japan, Aug. pp.202-204 (1993).
[3] W.Yokota, M.Fukuda, K.Arakawa,Y.Nakamura, T.Nara, T.Agematsu,S.Okumura and I.Ishibori, Proc. 13th Int.conf. on Cyclotron and Their applications,Vancouver, Canada, pp581-584(1992).
[4] T.Nara, W.Yokota, Y.Nakamura,M.Fukuda, T.Agematsu, S.Okumura,I.Ishibori and K.Arakawa, TIARA AnnualReport, vol.2, pp 194-195 (1992).
[5] S.Okumura, M.Fukuda, W.Yokota,Y.Nakamura, T.Nara, T.Agematsu,I.Ishibori and K.Arakawa, presented atthis report.
[6] T.Agematsu, K.Arakawa, S.Okumura,Y.Nakamura, W.Yokota, T.Nara,M.Fukuda, and I.Ishibori, Proc. 9thSympo. on Accele. sci. and Tech.,Tsukuba, Japan, Aug. pp437-439 (1993).
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JAERI-Revicw 95-019
Table 1 Results of Extracted Intensity and Transmission
Particle
H+
D+
4He2+
12C5+
16Q5f
1606+
20N e6+
20N e7+
20Ne8+
36Ar8+
36Ar10.
40A r8+
40 A r l I +
40Ar13+
84Kr20+
Energy
(MeV)
102030456070901035502050
100220
100
160
120
260
350
195
195
175
330
420
520
Har-monic
No.22111112212212
3
2
3
2
2
3
3
3
2
2
2
Frequency
(MHz)
14.9721.0312.7715.4617.6518.9221.1410.6319.7011.7610.6716.7711.8120.42
17.98
15.11
17.70
17.48
19.88
16.82
16.83
15.14
13.68
16.24
11.98
ExtractedIntensity
(e^A)105.05.0305.05.0101140205.52010
0.25
1.7
1.9
1.6
1.0
1.5
' 2.5
0.10
3.0
0.6
0.1
0.05
ExtractionEfficiency
(%)8077677957534829594969623277
34
58
53
70
63
63
43
73
86
63
72
Trans-mission
(%)272122142212
7.73.74.67.211171022
8.1
21
18
19
23
13
1.2
15
15
13
20
- 2 2 0 -
9. 4
JAERI-Review 95-019
First Operation of 18-GHz ECR Ion Source
W. Yokota, YAVu, Y. Saitoh, Y. Ishii, T. Nara and K. Arakawa
Advanced Radiation Technology Center, JAERI
IntroductionIons with mass to charge ratio (M/Q) less than
6.5 can be accelerated by the JAERI cyclotron, and Xe
ion may be a limitation with the OCTOPUS source
which has been used since the cyclotron facility was
completed. On the other hand, the researches require
heavier ion species including metal ions in wider
energy range [1], On this background, we constructed
a new ECR ion source with high performance in
generating highly charged ions and metal ions. The
design of the source, electric current supplies, a
microwave power supply and a beam analyzing system
is described in last annual report [2]. The detailed
design was completed by October, 1993. After being
manufactured, they were installed in the ion source
room cited on the basement of the cyclotron building
in February, 1994. The source was named ECR-18
after the microwave frequency.
Operational ExperienceThe first plasma was fired at the end of June,
1994 without feeding any gas, because of high
pressure of residual gas which was about 5xlO' 5 Pa as
a base pressure at the extraction chamber, but grew up
higher by one order during the plasma generation.
Vacuum in the plasma chamber cannot be measured
and we speculate it might be higher by one order than
that at the extraction chamber. The first generation
of Ar ion was carried out at the similar pressure, and
we observed Ar^+ in the middle of July.
For a while after that, we concentrated on
adopting a cooling system of the sextupole, since it
turned out that the coil temperature rose to 45 C,
which might lead to 1.5 % reduction of the permanent
magnet field, and might deteriorate the magnet due to
the heat cycle. The cooling is made by forced air fed
from an opening between the mirror and the solenoid
coils. The air passes through narrow gaps around 3
mm between the coils and outer surface of the
sextupole magnet cover, and goes outside from the
opening between the mirror coil and the plasma
chamber. Air flow at about 10 1/min can successfully
keep the sextupole temperature lower than 33 C.
The residual gas pressure became lower down to
l.SxlO^5 Pa at the extraction chamber after a number
of operations, and we observed Ar ions whose charge
states were up to 11+. We attached an additional
vacuum port at the end of the plasma chamber
equipped with a 50-1/s turbo-molecular pump (see Fig.
1). As a result, vacuum was improved to 8.8xlO"6
Pa, and A r ^ + was observed. However, the base
pressure rapidly grew five times higher at the
extraction chamber during operation. This was partly
caused by the hit of the beams onto slits, a Faraday
cup or a vacuum chamber, bacause the pressure quickly
responded to the microwave power and a drain current
of the extraction voltage supply. In addition, slow
increase of the base pressure was also observed which
doubled in an hour. It is assumed to be caused by
outgas from some materials heated inside or outside
the plasma chamber. The outgas source has not been
determined yet. The waveguide is not the oulgas
source. At the beginning of the test operation, it was
found that some parts of the waveguide were heated up
over 50 C at 500 W microwave power, especially
high at the vacuum window. Therefore heat radiation
fins were attached to the heated parts and blown by
fans. Every part of the waveguide is now as cool as
room temperature at power below 500 W. It is
considered that the outgas flowed into the plasma
chamber and prevented generation of higher charge
states than Ar1 2 + .
Charge State Distribution of Ar IonsIn generation of Ar ions, Ar gas flow rate can be
optimized, while feed of oxygen as a support gas
always reduces the ion beam currents. This
suggests that the plasma chamber is filled with so
much outgas that the pressure is out of control. The
charge state distribution of Ar ion is shown in Fig. 2.
The highest ion current was obtained at Ar8"1". This
distribution is similar to that for the OCTOPUS
- 221 -
JAERI-Review 95-019
source both in the optimum charge state and the
gradient of decreasing current with charge state.
The typical operating parameters for Ar1 2 + are
as follows; Imirrorl = 700 A, Imirror2 = 665 A,
Isolenoid = 434 A and Pmicrowave = 300 W, Vex=8
kV (see Fig. 1 for the coil layout). The solenoid coil
is used around 60 % of the full excitation which
corresponds to the mirror ratio 2.4. The solenoid field
is higher for higher charge state; the field for Ar1 2 + is
4 % higher than that for Ar8+, for example.
We checked the demagnetization of the sextupole
magnet to confirm if it might cause the charge state
limitation. The sextupole field strength measured
before the first operation was 1.40 T at the magnet
surface and 1.25 after observation of Ar1 2 +. This
indicates that demagnetization is not appreciable
within the measurement error. The field strength is
enough to generate much higher charge state than 12.
As a result, charge state distribution is expected to
change better by improvement of the vacuum so that
the optimum charge becomes higher and the gradient
of decreasing current more moderate.
Summary
The test operation of ECR-18 started in July,
1994, by using Ar ion generation. A vacuum pump
was added at the end of the plasma chamber for higher
vacuum, and charge states up to 12 were observed.
Further improvement of vacuum is needed to attain
higher source performance. The metal ion generation
method, which has been developed with another ECR
ion source now in use, will be applied to the ECR-18
in the next stage. After the completion of
development, the source will be connected to the
cyclotron.
References
[l]R.Tanaka, KArakawa, W.Yokota,
Y.Nakamura, T.Kamiya, M.Fukuda,
T.Agematsu, H.Watanabe, RAkiyama,
M.Maruyama, Proc of Int. Conference on
Cyclotron and Their Applications, May 8-
12,1989, Berlin, Germany, p.566.
[2]W.Yokota, Y,Wu, Y.Saitoh, Y.Ishii, T.Nara
and K.Arakawa,JAERI TIARA auuanl report
1993 (vol.3), p.211
solenoid coil mirror coil I
soli iron youpa l le t
e i i u e l l e n s
ext r act i o
'chanter
1 5 0 0 l / s I M P
Fig. 1 Schematic drawing of the ECR-18.
8.0 10.0
Charge State
Fig. 2 Cliarge state distribution of Ar.
12.0 14.0
- 2 2 2 -
JAERI-Review 95-019
9 • 5 Temperature Increase of Power Cable Assembly Laid inSleeve through Shielding Concrete at Cyclotron Facility
Yoshiteru NAKAMURAAdvanced Radiation Technology Center, JAERI
IntroductionA large number of power cables have to
be penetrated thick shielding walls, becausethe power supply room is far from the targetrooms and the cyclotron vault where theirloads such as electromagnets are installed.Figure 1 shows an example of the installationof sleeves in the cyclotron facility beforeplacing of shielding concrete.
Fig. 1 Installation of sleeves beforeplacing of shie'dh.-g concrete.
Many power cables have usually beenlaid in each sleeve so as to occupy 30 % ofthe opening space at least for shielding ofradiation streaming. In this geometricalarrangement, the great part of the quantity ofheat released by the cable conductors may beaccumulated in a cable assembly. Therefore,temperature increase caused by internalheating of the cables should be estimated forsafety operation.
The heat resistance for temperatureincrease of the cable insulator was made sureby comparison between thermal analysis andtemperature measurement [1].
Analysis of temperature increase(1) Quantity of heat
It was found out that the highestequilibrium temperature is reached for thecable assembly, which is run through thesleeve No.3-4 between the cyclotron pit room
and the cable transit room as shown in Fig. 2.This assembly mainly supplies the electricityto a magnetic channel and 3 trimming coilsfor the cyclotron. Most of the quantity ofheat in this assembly is generated from 16power cables with a cross-sectional area ofthe central conductor of 150 mm2 shown inTable 1.
Cy c l o t r onp i t r o o m
( B I )
T h e r m o c o u p l ep o s i t i o n• 1 - 1 0
C y c l o t r o n ^p i t r o o m ; ;
( B I )• / / -
/
Fig. 2 Layout of sleeves and positionsof temperature measurement.
Table 1 Heat sources of caDle assembly inthe sleeve No.3-4.
Conductor
mm2
150
15038
5.5
3.5
Total
Resistance
mfi/m0.123
0.123
0.481
3.32
5.22
~~"
Current
A260
200
52
10
4
Number ofcables
10633
1537
Quantityof heat
kcal/h/m
71.5
25.43.4
0.8
0.3
101.4
The quantity of heat in the cableassembly per unit length ,QT, is 101 kcal/h/mat 30 °Q, when the maximum currents of 600A and 1300 A arc fed to the trimming coilsand the magnetic channel, respectively.
- 223 -
JAERI-Review 95-019
(2) Temperature at sleeve surface
A sectional model for thermal analysis ofsurface temperatures is shown in Fig. 3.First, it is assumed that the cable assembly inthe sleeve is suspended in air, the temperatureat the outer surface of the surroundingconcrete ,Ti, is 30 X^ and the cyclotronsystem is operated continuously during oneweek. The averaged temperature increase iscalculated at 1.9 V over the shieldingconcrete bulk, and the inner surfacetemperature of the sleeve ,T2, reaches 36 CC.
Cableassembly
Gap
Sleeve
Temperature: 30 °C
Shieldingconcrete
Fig. 3 A sectional model for thermal analysisof surface temperatures,
(3) Surface temperature of cable assembly
Natural convection under coaxial tubemodel in enclosed fluid layer and radiation arcpredominant effect for heat transfer from thecable assembly to the shielding concrete. Athermal analysis model for the assemblyconsisting of the 24 cables is illustrated withFig. 4.
The 21 cables which have the cross-sectional areas of the conductors less than150 mm2 are approximately replaced with 8cables, of which the total cross-sectional areais equivalent with that of the 21 cables. Theanalysis model can be thought so that the 24cables are closely contacted with each otherfor the safety-side analysis.
An equivalent diameter of the assemblymodel contributing to the convection loss isestimated at 0.125 m from geometricalsimplification. The total areas of outer
surface related to radiation loss is evaluated at0.60 m2 per unit length. The shape factorconcerning the radiation loss is 0.43, sincethe cmissivities for inner and outer surfacesare assumed at 0.6.
,,24.0Equivalent circle
Central region (T4)
Fig. 4 A thermal analysis model of cableassembly.
The surface temperature of the cableassembly was obtained by using the rule oftrial and error under the equilibriumcondition. Finally, the complete balancebetween heat generation and loss wasestablished at a temperature ,T3, of 72 °C.
(4) Maximum temperature in cable assembly
The temperature difference between the innerand outer surfaces of the insulation layer ineach power cable ,ATc, is subject to thermalconduction process. A thermal conductivityof the insulator in the cthylene-propylenerubber insulated hypalon sheathed flexiblecable (PHCT) [2] is 0.26 kcal/m/h/°C. Thetemperature difference ATc is calculated at1.5 <€.
It is clearly shown that the highesttemperature at the central insulator in the cableassembly ,T4, is only several degrees higherthan the surface temperature of 72 9C, inconsideration of the temperature differenceATc and the number of insulation layers fromthe outer surface to central region.
- 2 2 4 -
JAERI-Review 95-019
Temperature measurement
(1) Measurement method and position
Figure 2 shows the arrangement ofsleeve No.3-4 and the positions of sheathedtype C-C thermocouples for temperaturemeasurement. Both ends of the sleeve aresealed off to meet the requirement of fire-resistant structure. The measurement datawere recorded at intervals of a few tensminute using a digital multi-point recorder.
(2) Measured result
The temperatures almost reached asteady state at about 5 hours after startingcyclotron operation. A relationship betweenthe quantities of heat and the temperatureincreases at different positions is shown inFig. 5. It seems that the temperatureincreases rise with the quantity of heat as aquadratic function.
Thermocouple:positions
0 10 20 30 40 50 60 70 80wH Quantity of heat (kcal/h/m)
Fig. 5 A relationship between the quantityof heat and temperature increase.
The temperature increase at thethermocouple position of No.5 & 6 ,ATM,can be approximated by
ATM = 2.36xW3 Qi2 + 9.14xW2 Qr. (1)
Summary
The maximum temperature increase isevaluated at 36 °C from the equation (1) forthe QT value of 101 kcal/h/m. This valueagrees well with the calculated value of 34 Vby the thermal analysis. The maximumpredicted temperature in the cable assembly isa little less than 80 V, which is the limitinghottest-spot temperature of the PHCTinsulator.
In actual fact, since some parts of thecable assembly contact with the sleeve surfaceand the section of the cable assembly has notthe close-packed structure, the dissipation ofthe generated heat is underestimated in thethermal analysis because of the conduction tothe surrounding concrete and the additionalradiation due to the increase of the totalsurface area of the assembly.
Therefore, the author concludes that thetemperatures of the power cable assemblieslaid in long sleeves at the cyclotron facility donot exceed the tolerable temperature of thecable insulator even though maximum ratedcurrents are supplied to their loads.
References
[1] Y. Nakamura, W. Yokota, et. al,JAERI-M 94-054, 61p (1994)
[2] M. Hagiwara, Y. Morita, et. al,Furukawa-dcnko Jiho, vol. 75, pl71(1985)
- 2 2 5 -
JAERI-Review 95-019
9 . 6 Development of high energy single ion hit system combined
with heavy ion microbeam apparatusT.Kamiya, T.Suda and R.Tanaka
Advanced Radiation Technology Center, JAERI
1. Introduction
The JAERI heavy ion microbeam
apparatus has been applied to analysis of
transient phenomena in single event upsets of
semiconductor devices[l-3]. Transient electric
current induced by a single event was measured
by using a wide-band sampling oscilloscope
under microbeam currents of less than the order
of femto ampere[4,5]. However, continuous
random ion hit on the same position give rise to
more radiation damage. Therefore, the
experiment should be carried out under
irradiating conditions allowing a single or
predetermined number of ion hits.
To make a single ion hit a particular
point, a single ion hit system has been
developed and was combined with the heavy
ion microbeam apparatus to control the number
and the timing of precisely positioned ions.
The performance has been tested for single ion
detection efficiency, beam switching
characteristics and hit timing control. This
paper describes recent technical progress on the
single ion hit system and its performance.
2. Single ion hit system
The single ion hit system consists of a
single ion detector and a fast beam switch. In
the single ion hit system, the fast beam switch
is actuated by a detection signal from the single
ion detector, in order to prevent following ions
passing through the switch from hitting the
target. The schematic diagram of the system
combined with the microbeam apparatus is
shown in Fig. 1.
Single IonDetectionSystem
• Target
MicroChannel Plate(MCP)
Fig. 1 Schematic diagram of single ion hitsystem
Fig. 2 Single ion detector with annular type
MCP.
- 2 2 6 -
JAERI-Rcview 95-019
A single ion detector consists of a pair
of annular type micro-channel plates (MCP),
both of which obtain their signals from
secondary electrons generated by the single
ion, the first from an ultra-thin carbon foil
penetrated by the single ion, and the second
from a target specimen hit by it. A photograph
of the detector is shown in Fig. 2.
The fast beam switch consists of a 500
V power supplier and an electrostatic deflector
located just after the microslits (MS) in the
beam line, which deflects ions to be cut at the
divergence defining slits (DS). The high
voltage can be dropped by a reset signal of TTL
level positive pulse supplied from a pulser, as
shown in Fig. 1. This means that the timing of
single ion hit is controllable within the variation
of each time interval due to random ions
passing at the beam switch. The number of ion
hits on the same targeting position can be also
controlled according to the preset hit number.
3. Detection efficiency and switching
time
At the first place, the detection
efficiency for incident ions was measured on an
MCP for 15 MeV nickel ions from the tandem
accelerator. The detection efficiency was
evaluated at 100 %. The MCP noise
component was less than 10 counts per second.
A detection efficiency for cc-rays from 241Am
was 90 % under the same detecting condition.
The difference in the detection efficiencies can
be explained by that of the emission efficiency
of secondary. Improvement of the detection
efficiency is necessary for relatively low LET
ion beams. It is expected that there is not large
difference between the detection signals of the
MCPs on the target side and the carbon foil
side. The contribution of the error coincidence
signal generated by noise signals can be
neglected in comparison with the real
coincidence signals.
Fig. 3 Oscillographic traces of high voltage
of the fast beam switch and the single ion
detection signal. The switching time is given
by the time difference between two pules.
Figure 3 shows an example of the time
delay of 150 ns from a detection of a single ion
to the rising of the high-voltage in the fast beam
switch in an oscilloscopic measurement.
However the switching time is determined not
only by the ».blay time but also the flight time of
the ions between the beam switch and the
single ion detector. The flight time of 15 MeV
Ni ions is evaluated at 570 ns for that flight
path of about 4 m. Therefore the switching
time is 720 ns in this case. The multiple ion hit
of the following ions which pass though the
- 2 2 7 -
JAERl-Review 95-019
beam switch within a switching time after a
single ion hit should be considered to reduce
erroneous hits. Since ion incidences at the
beam switch are random events, the probability
that an ion incidence occurs within a given
short time t, which is 7.2 X 10"7 s in this case,
is given by
p = 1 - e"'/T
where x is the mean time interval between
successive two ion incidences which is given
by inverse of the number of ions passing per
unit time through the fast beam switch.
Therefore the incident beam current should be
reduced several order in magnitude smaller so
that the value of p may be tolerable in a single
ion hit experiment. If the tolerable value of p
is 0.01, x should be larger than 7.2 X 10"5 s,
according to the equation, and the beam current
should be less than 2 fA. We will be able also
to control the beam current of less than femto
ampere order in an accuracy of 0.01 only by
frequency control of the HV-off pulse in the
fast beam switch.
4. Summary
A high-energy single ion hit system
was combined with the JAERI heavy ion
microbeam apparatus. The timing and the
number of ions hitting the target can be
controlled by a single ion hit system consisting
of a single ion detector and a fast beam switch.
Detection efficiencies for single ions
were evaluated at 100 % for 15 MeV Ni ions
by using annular type micro-channel plates.
The switching time of 15 N4eV Ni ions is
evaluated at 720 ns. The conJroIIable range of
the beam current for the periodic ion incidence
at the target was estimated at femto ampere
order or less with a multiple ion hit probability
of 0.01 within the switching time.
Acknowledgment
The authors would like to thank Drs.
Nashiyama and Hirao for their valuable help
and discussion in experiments. The author also
acknowledge the assistance from the all the
staff of JAERI electrostatic accelerator group.
References
[1] T. Kamiya, et al, Nucl. Instr. and Meth.
B64 (1992) 362.
[2] R.Tanaka, Proc. of the 5th Japan-China
Joint Symp. on Accelerators for Nuclear
Science and Their Applications, Osaka, Japan
(1993)201.
[3] R.Tanaka , et al, Nucl. Instr. and Meth.
B79 (1993) 432.
[4] I.Nashiyama, et al, IEEE Trans, on Nucl.
Sci. NS-40, No.6 (1993) 1935.
[5] T.Hirao, et al, Proc. of 4th. Int. Conf. on
Nuclear Microprobe Technology and
Applications, China (1994), to be published in
Nucl. Instr. and Meth. B.
[6] H.Thibeau, et al, Nucl. Instr. and Meth.
111(1973)615.
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JAERI-Review 95-019
9 . 7 2 MeV Sub-micron Microbeam Focusing
T.Kamiya, T.Suda and R.Tanaka
Advanced Radiation Technology CenterJAERI
1. Introduction
Submicron beam technique is under
development using the light-ion microbeam
apparatusfl] connected with the 3 MV single-
ended accelerator^] in TIARA, JAERI[3].
Figure 1 shows a schematic diagram of the
whole system consisting of the accelerator, the
beam energy analyzing system and the
microbeam lens system equipped with a
precision doublet quadrupole magnet. A
minimum beam spot size of 0.4 X 0.4 |im2 in
FWHM so far has been obtained with a beam
current of 77 pA[l].
3MV SINGLE-ENDED ACCELERATOR
BEAM ENERGY ANALYZING SYSTEM
MICROBEAM FOCUSING SYSTEM
MAGNETTARGE
Fig. 1 Plane view of the accelerator, the beam
transport system and the microbeam line.
We are still aiming to achieve a smaller
beam spot size of less than 0.25 |im with
higher beam current for the highest spatial-
resolution in materials analyses using PIXE,
RBS and NRA[2-4]. Since the detectable limit
in such ion beam analyses is set by the
minimum incident ions required at a beam spot
on a specimen, the high beam current is
required to reduce analyzing time at the beam
spot, especially for high-resolution analysis.
We measured the beam size and the
beam brightness using 2 MeV helium ions
under the condition that the voltage ripple of the
accelerator and the energy resolution of the
beam energy analyzing system are set at the
minimum values, respectively. We also
calculated the relationship of the beam
brightness and the beam size with the energy
spread of the beam extracted from the
accelerator and the energy resolution of the
beam energy analyzing system by using the
second-order calculation the code,
TRANSPORT^].
This paper describes the result of beam
size measurements and calculations.
2 Measurement of brightness and beam
size
The beam size and the beam current at
the target was measured for 2 MeV He ion
beam under the conditions of a terminal voltage
ripple of ±2.0 X 10"5 and an energy resolution
of the beam energy analyzing system of 5.6 X
10~5. The X-Y gaps of the microslits were
varied from 2 X 10 to 18 X 90 urn2. The gaps
- 229 -
JAERI-Rcview 95-019
of the divergence defining slits at the distance
from the microslits of 4 m were fixed at 600 X
600 fim2. The beam size was measured by
using a test sample, a silicon wafer with a line-
and-space relief pattern on the surface[8,9].
The results of beam size measurements
are shown in Fig. 2. The beam sizes are
plotted by open and closed circles indicating the
beam size in the horizontal and the vertical
directions, respectively. Figure 3 demonstrates
a secondary electron image of a part of the test
sample with high spatial resolution of
submicron order. The smallest beam size of
0.3 X 0.3 (im2 and the beam brightness of 9.5
pA p.m"2mrad"2 were measured at the microslit
gaps of 4 X 20 urn2. Because of similar
brightness to the previous result[l], the smaller
beam current and also the smaller beam size can
be explained by the smaller beam divergence,
which varied both the beam current and the
aberrations. In order to not only reduce the
beam size but also increase the beam current,
the optimization of the microbeam lens system
such as the geometric alignment should be
made more precisely to decrease the coefficients
of the parasitic aberrations.
3. Calculation and discussion
The beam size and brightness were
calculated for two selected conditions of
terminal voltage ripples of ±2 X 10"^ noted by
Srip and ±1 X 10"4 by Lrip, and also for two
values of energy resolutions of the beam
10.0
E
gCO
1.0
0.1
Calculaled (1).(2)X
.. .Ca lcu la ted(4 )XO Measured X
.Ca lcu la led (3) Y_ - • . Calculated (4) Y
• Measured Y
Measured tor 2 MeV He ;
c
10
Microslit Gap ( nm)
100
Fig. 2 Measured and calculated beam sizes vs.gaps of the microslits. The measured beamsizes of X and Y are indicated by open andclosed circles, respectively. Calculated beamsizes in four cases: (1) Sri and Sres, (2) Srip andLntt (3) Lrip and Sm, and (4) Lrip and Lm. areindicated by rigid and broken lines with variouswidth for the horizontal (X) and the vertical (Y)directions, respectively.
Fig. 3 Secondary electron image of the line-and-space relief pattern on the surface of asilicon wafer, which was scanned by 2 MeVHe microbeam with the beam size of 0.3 X 0.3|im2, with the beam current of 11 pA and withthe scan area of about 12X12 jxm2. Theresolution of the image is 150 X 150 pixels.
- 2 3 0 -
JAERI-Revicw 95-019
energy analyzing system of 5.6 X 10"^ noted
by Sres and 2.8 X 10'4 by Lres, corresponding
to the object slit gaps of 0.2 and 1.0 mm,
respectively. It means that there are four
combinations: (1) Srip and Sm, (2) Srip and Lre?,
(3) L,p and Sres, and (4) Lrip and Lre,
Calculated results of the full width of
the beam at the target are summarized in Fig. 2
with the measured ones. No dependence of the
beam size on the energy resolution of the beam
energy analyzing system for the small terminal
voltage ripple, Srip means that the energy
variation is dominated by the ripple. However
the energy variation of the beam extracted from
the ion source may be larger than the energy
resolution of Sres, which results in the
calculations for (3) and (4).
The measured data deviate from the
calculated one both in the relatively wide and
narrow microslit gap regions. The deviation in
the wide gap is partially due to the deference in
the way of the beam size estimation between the
calculation (the full width) and the measurement
(FWHM). It is presumed that the higher order
intrinsic spherical aberrations and some
parasitic aberrations such as the rotational one
still contribute to the saturation at the 0.3 [im
level.
4. Summary
The JAERI light-ion microbeam
apparatus was constructed for high spatial-
resolution beam analysis using PIXE, RBS or
NRA with sufficient beam current. The
minimum beam spot size of 0.3 u,m with a
beam current of 11 pA was obtained with a
doublet quadrupole lens system. The beam
quality will be improved by optimization of the
operation parameters of the RF type ion source
or by replacement with any other type ion
source with higher brightness and with smaller
energy variation in order to obtain the beam
current of 100 pA with the beam spot size of
0.25 |im. Another method of improvement is
to decrease the coefficient of the parasitic
aberrations by optimization of the microbeam
lens system such as the geometric alignment.
Acknowledgments
The authors acknowledge the assistance
from the staff of the JAERI electrostatic
accelerator group.
References
[1] T.Kamiya, et al, Proc. of 4th. Int. Conf. on
Nuclear Microprobe Technology and
Applications, China (1994), to be published in
Nucl. Instr. and Meth. B.
[2] J.A.Cookson, Principles & Applications of
High-energy Ion Microbeams, edited by F.Watt
and G.W.Grime, (Adam Hiller, Bristol, 1987).
[3] K.Traxel, Nucl. Instr. and Meth. B50,
(1990) 177.
[4] M.Takai, Nucl. Instr. and Meth. B85,
(1994)664.
[5] K.L.Brown, SLAC-91, (1977).
[6] I.Ohdomari, et al, Nucl. Instr. and Meth.
B54, (1991) 71.
[7] I.Ohdomari, et al, Nucl. Instr. and Meth.
B72, (1992) 436.
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JAERI-Review 95-019
9 . 8 Fluence Uniformity Measurement of Two- DimensionallyScanned Radiation Field of 400 kV Ion Implanter
Kiyoshi MIZUHASHI, Suwat BUNNAK*. Kiyonori OHKOSHI,Satoshi TAJIMA and Ryuichi TANAKA
Advanced Radiation Technology Center, JAERI*Office of Atomic Energy for Peace (OAEP) in THAILAND
1.IntroductionAccurate measurement of the fluence
uniformity of two-dimensionally scanner radiationfields is required for various ion irradiationexperiment using a 400 kV ion implanter. Weadopt an electrostatic type beam scanner foruniform irradiation. For study of fluence uniformityin target fields of the ion implanter, thin plastic filmdosimetry is now the best candidate because thethickness of the radiation sensitive layer ofdosimeter should be thinner than the penetrationrange of incident ions.
2.Design of beam scannerA beam scanner was installed on a general
purpose beam line (IA) to provide uniformradiation field for a wide target area. We designedan electrostatic type scanner, which have higherfrequency characteristics than magnetic-typeone. The main design parameters are listed inTable 1.
Tablei. Main design parameters of beam scanner
Length of electrode (X,Y)Gap distance of electrodesScanning voltageScanning frequency
400 mm40 mm
- ± 3 k V10-1,000 Hz
Distance from Scanner to Target(X)00
2,200 mm1,800 mm
The scanning width W was calculated by theequation
W =
Where Li is the electrode length (mm), L2, thedistance between the target and the scanner(mm), d, the gap distance of electrodes (mm), V,the scanning voltage, and Vo, the acceleratingvoltage (kV). This scanner has a capability ascanning area of 160 X120 mm at ± 3 kV.However, the practical maximum of the scanningarea is 20 X 20 mm in consideration of beamtransport for IA line.
3.Measurement methodA simple method to measure the uniformity of
scanned beam irradiation is spectro-photometry.After irradiation of a film dosimeter, the beamfluence distribution is measured by the spectro-photometer in terms of radiation induced opticaldensity.
We adopt the GAF (GAFCHROMIC) dosimeterfor low-energy ions, because it has a very thinradiation sensitive layer of 7 p. m , which is coatedon 100 p.m thick polyester substrate.
3.00
2.50
•<2 2.00 rCD
2 1.50s£1.00
0.50
0.000 1 2 3 4 5 6 7Relative Dose In Terms of Irradiation Time
Fig.1 Relative dose response of GAF dosimeter(analysis wavelength: 500 nm)
/
/
....
i i i .
, , , .
• ' • •
. . . .
- 232 -
JAERI-Rcvicw 95-019
It has been used for 7 , X rays and electronbeam dosimetry as one of commercially availablefilms 1). Irradiation makes the color of GAFdosimeter change from transparence to deepblue. Using the relative dose response as shownin Figure.1, the radiation optical density (O.D.) atan analysis wavelength can be interpreted torelative absorbed dose. The LET effect on thedose response of GAF dosimeter has not beentaken into account in the interpretation.
4. ResultOn the basis of above design, we fabricated
the scanner and checked the fluence uniformityin the scanned radiation field using 400 keVproton beams. GAF sheets were irradiated for 5second with a beam current of 1 nA. Thescanning frequency was 179 Hz and 562 Hz inthe X and Y directions, respectively.
The proton beam has a long penetration range,which almost passes through the sensitive layerof GAF dosimeter. The dose response wasmeasured in terms of O.D. by using a scanningtype micro-spectrophotometer ( Model NML-301) with an analyzing light size of 0.5 X 0.5 mm.Figure.2 shows a relative equi-dose map of thescanned radiation field using 0.02 step contourlines in terms of O.D.. The fluence or doseuniformity in the area of 20 X 20 mm is within ±7%, except for the fringe of the radiation field.
Xaxis(mm)
Fig.2 A relative equi-dose map for 400 keVprotons (Contour lines: 0.02 steps)
5.Response of GAF dosimeter for Ar beamThe dose response of GAF dosimeter was
measured using Ar+1 beams of energies rangingfrom 100 to 400 keV. Figure. 3 shows O.D.values and the penetration range as a function ofthe ion energy. The O.D. value has a threshold atan energy of about 200 keV. The threshold inthe O.D. change suggests that there is a very thinradiation-insensitive layer on the surface of theGAF film, or ion spattering makes the GAFdosimeter radiation-insensitive in the thin surfacelayer.
o.o0.5 1 1.5 2 2.5 3 3.5 4
Ar energy (X100 keV)
Fig.3 O.D. change and penetration range inpolyester as a function of Ar ion energy
6.SummaryA beam scanner was installed on IA line of the
400 kV ion implanter, and the fluence uniformitymeasurement of the scanned radiation field wasstudied using GAF dosimeters. From spectro-photometric analysis of irradiated GAF sheets, theuniformity over a 20 X 20 mm area is estimatedwithin ±7%, except for the fringe part.
REFERENCE1).W.L.Mclaughlin et al., Nucl. Instr. and Meth.
A302(1991)165
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JAERI-Rcvicw 95-019
9 . 9 Acceleration of Cluster Ions by 3 MV Tandem
Y. Saitoh, S. Tajima, I. Takada, K. Mizuhasi, S. Uno, K. Okoshi,Y. Nakajima, and Y. Ishii
Advanced Radiation Technology Center, JAERITAKASAKI
1. IntroductionImplantation of cluster ions, which
consist of many atoms, in materials hasbeen remarked by their strange behaviour,and expected for materials modification.Some experiments have been done by usingcluster beams in the energy range about 100
keV and interesting results have beenreported. Since then, implantation of MeVenergy cluster ions has attracted moreattemtion[l]. MeV cluster ions offer thepossibility of bombarding material surfaceinstantaneously with a large number of atomswithin a very small area. As a result, anextremely large energy is deposited on thematerial. Such kind of processes are of greatinterest not only for materials modificationbut also fundamental materials science[2]. Inthis paper, the experimental results ofaccelerating C2~s, Si2~4, and 02 clusterions to 6 MeV and optimization of ion sourceconditions with carbon clusters are reported.
2. Generating cluster ionsNegative cluster ions are extracted
from a cesium sputter type ion source(nec.-SNICSS). To increase the postaccelerating cluster beam current of carbon,the ion source conditions, such as cesiumsputtering energy, structure andtemperature of the sputtered material (sputter cathode ) have been optimized. As aresult, graphite-form cathode with a
cooling system can provide the most effectivecarbon cluster mass spectrum, and there areno relationship between the mass spectrumand the cesium sputtering energy in therange of 6 to 8 keV. The mass spectrumsin the best condition is shown in Fig. 1. Fe2O3 and the single crystal silicon are used forgenerating O2 and Si cluster ions,respectively, because these materials canprovide the maximum beam current of singleatom ion. The Si cluster mass spectrum isshown in Fig. 2.
3. Accelerating cluster ionsThe 3MV tandem accelerator can
make cluster ions of MeV energy, but mostof cluster ions are dissolved into smaller sizeor atoms by collisions with the chargeexchange gas(N2) in the high voltageterminal. We could obtain positive clusterions passing through the gas part by reducingthe gas pressure by one order comparingwith the normal operation. As a result, 1.5
nA of Cs, 1 nA of Si<, and 3.7 nA of O2cluster beams were obtained. These beam
intensities are enough for fundamentalexperiments of materials science. Eachcluster beam current respecting to the gaspressure in the energy of 6 MeV (we couldnot find multi-charged cluster ions by theFarady cup in this time) is shown in Fig. 3~—5.
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JAERl-Review 95-019
References
[1] Shen Dingyu et al., Nucl. Instr. andMeth. A 348(1994)47-50[2] K. Boussofiane et ai., Nucl. instr. andMeth. B 82(1993) 156-160
C C2 C3 C4 C5 C6 C7 C8
Fig.1 Carbon duster mass spectrumextracted from the ion source
100
o
m
0.01
Fig.2 Silicon cluster mass spectrumextracted from tne ion source
1Q-'
10'7
I10'9
1 I I I 1 I I I t I I I I I 1 I I
0 2 4 6 8 10
pressure (x10'8) Torr
Fig.3 Beam intensity of high energy Carboncluster with respect to stripper gas pressure
0 2 4 6 8 10
pressure (x10'a)Torr
Fig.4 Beam intensity of high energy Sicluster with respect to stripper gas pressure
8.0 10.0 12.0
Pressure (x10'°) Torr
Fig. 5 Beam intensity of 02 withrespect to stripper gas pressure
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JAERl-Review 95-019
9 - i o Energy Calibration of Single-ended Accelerator
Y. Ishii, S. Tajima, I. Takada, K. Mizuhashi, Y. Saitoh,S. Uno, K. Okoshi, T. Kamiya and R. Tanaka
Advanced Radiation Technology Center, JAERI
1.IntroductionThe 3MV single-ended accelerator
was designed to have a voltage stabilitybelow ±lxl0-5(8V/V) and the stabilityhas been already measured by using highaccuracy dividing resister and CRdividing system1). The beam qualitywhich dominates the performance of amicrobeam2) in submicron-level mostlydepends on the energy spread of theaccelerated beam, and the energy spreaddepends not only the voltage stability butalso the energy spread of the injectionbeam from the ion source.
There are two methods fordetermining the beam energy; the one isthe method using the analyzing magnetand the another is the method usingnuclear reaction. In the former, adefining of the absolute energy isdifficult because the bending radius ofthe magnet can not be determinedexactly. The latter allows to calibrate theenergy accurately and also to measurethe energy spread. The nuclear
resonance reaction of 27Al(p,y)28Si 3>i4>emits y-ray at a specific energy,0.992keV, of proton, and the width ofresonance is 50eV. If we use a thintarget in which energy loss for protoncan be negligible, the beam energyspread may be defined with a resolutionof about 50eV. Since the width of theresonance reaction is very small, it isnecessary to know the absolute beamenergy before measuring the energyspread. The voltage meter of the single-ended machine has not been re-calibratedafter exchange the dividing resisters. Theacceleration energy was calibrated usingthe above reaction at about 1MV.
This paper reports the result ofthe beam energy c.\-Oration of the single-ended accelerator.
2. Experiment
The chamber for energymeasurement shown in Fig.l wasconnected to the beam line of the single-ended accelerator. The thickness of thealuminum target is O.lum. The target isinsulated from ground because a bias-voltage up to lOkV is applied to thetarget. The y-yield at an energy of1.77MeV from the target was detectedwith a 3"x 3" Nal scintillation detectorplaced close to the target at an angle 90°against beam axis.
The proton energy was variedfrom 1012keV to 1018keV on the meterindication and the y-yield wasnormalized by scattered protons detectedwith a SSD in the chamber.
3. ResultAn energy shift of 22 keV was
observed between the reaction energy of992 keV and a indicated energy of 1014keV as shown in Fig. 2. Therefore, theindicated voltage measured by dividingresisters is 22 kV higher than theabsolute voltage around 1MV.
Next step, We will apply thevariable bias-voltage to the thin target,0.01 Jim of thickness, to finely controlethe beam energy. The beam energyspread will be obtained with highresolution in this method.
Reference1) Y. Ishii et al., TIARA annual reportVol.3 p227 (1993)
2) T. Kamiya et al., TIARA annualreport Vol.3 p 196 (1993).3) J.W. Mayar and E. Rimini, Ion BeamHandbook for Material Analysis,Academic Press, 1977.
4) S.A. Brindhaban et al., Nucl. Instr.Meth. A 340(1993)436.
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JAERI-Review 95-019
Fig.l The block diagram of the energy measurement system.
800
27Al(p,
Resonance Energy=992keV,
Target: Al(lOOnm) on Ta
1010.0 1012.0 1014.0 1016.0 1018.0 1020.0
Energy (keV)
Fig.2 Relation between the terminal voltage and y yield of 27Al(p,y)28Si.
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JAERI-Review 95-019
9 . 1 1 Preliminary Study of Ultra-Fine Microbeam II
Yasuyuki Ishii, Ryuichi Tanaka and Akira IsoyaAdvanced Radiation Technology Center, JAERI
1. IntroductionHigh-energy ion microbeam of a
beam size of 0.1 (im order will be usefulfor analysis of the inner-structure andcosmic ray induced singe-event effectsof microelectronic devices.
We are planning to produce anion microbeam of 0.1 nm or less, byusing an acceleration lens, consisting ofentrance aperture lenses. This type oflens makes possible high degree ofdemagnification, being associated withthe acceleration process, owing to itsproperty of low spherical aberra-tion[l,2]. This lens makes a very smallvirtual image close to the entranceaperture when the ratio of final toincident energies is large. A ultra-finefocus is formed at the target as a realimage by using another accelerationlens.
To take full advantage of theaccel lens in reducing the beam size, it ishighly desirable to use an injectionenergy as low as possible. As an effort inthis direction, we have developed a wayto extract ion beam of nearly thermalenergy from discharge plasma of aduoplasmatron-like ion source. A lensoptics calculation indicates that using thistype of injection beam of very lowenergy, high degrees of demagnificationcan be attained with the low sphericalaberration enough to get a 0.1 urn focus.In this situation an important require-ment for the initial beam is that the ionenergy spread is small enough.
This article describes results ofmeasurement on the energy spread ofthe beam which were obtained by theabove-mentioned method.
2. Ion Source for Ultra-Fine MicrobeamApparatus
To meet the above requirements,we made an ion source, which is similarto the duoplasmatron in the construction,as shown in Fig.l, but is made of non-magnetic matcrial(SUS304) as the anodeelectrode to eliminate abrupt change ofthe magnetic fieid strength along thebeam path at the exit hole position.Magnetic flux, then, extends nearly inparallel up to an extraction
This anode exit hole constructionallows the ions of plasma state to get outof the hole almost without acceleration,
and to be transmitted to the extractionelectrode. The ions are accelerated fromthe plasma beam in high vacuum(p<5xlOJ'Pa), so that collisions withresidual gas are not expected to occur,conserving the original energy width
3. Production of Low-Energy Ion Beamwith a Small Size
A voltage of 20 to 50V is appliedto the extraction electrode. Ions areaccelerated from a tip of the plasmabeam extruding from the anode exit holeto the extraction electrode, and the ionspassing through a small hole (0.1mm indiameter) on it are further accelerated byan accelerating gap just behind the hole.By this way a considerable amount ofion current(10-50nA) could be obtainedon a collector(with a slit lmm indiameter) a part from about 10cm fromthe injection slit with a fairly lowemittance at very low acceleratingvoltage (much less than 100V).
4. Energy Spreads of Extracted BeamA uniform electric-field type
energy analyzer[3], as shown in Fig.l,was made to measure the energy spreadof the ion beam. In this configuration acollector current of the analyzerrepresents the intensity of the componentwhich corresponds to the voltagebetween the electrodes.
Observed spread of the ionenergy in the H+ beam is shown in Fig.2.Here the reppeller potential is sweptaround the anode potential of the ionsource. The horizontal axis representsthe accelerating voltage relative to theanode.
The energy spreads were evalu-ated to be less than 2eV in FWHM.Actual energy spreads should be a littleless than these values when theinstrumental width is subtracted.
5. SummaryA duoplasmatron-like ion source
with a special exit hole design was testedfor extraction of extremely low energyions. A non-magnetic anode electrodewas used to extract ion beam of plasmastate from the source. H2
+ beam of aconsiderable intensity could be obtainedthrough a hole of 0.1mm in diameter onthe extraction electrode with the energy
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JAERI-Rcview 95-019
much less than lOOeV. The energyspread of the H2* beam was analyzed tobe less than 2eV in FWHM by using auniform electric field-type energyanalyzer. This result meets the require-ments for the initial ion beam to formthe ultra-fine microbeam of a size ofO.lnm.
Reference[1] A. Isoya, Proc. Int. Conf. on
Application of Nuclear Techniques.Crete, Greece, (1990) P.334
[2] A. Isoya. Proc. Int. Conf. onEvaluation in Beam Applications.Takasaki, Japan, (1991) P.397
[3] J. R. Pierce, Theory and Design ofELECTRON BEAMS (D. VANNOSTRAND COMPANY, INC., NEWYORK, 1954)P.2O
— H2 or Ar gas
IntermediateElectrode
AnodeElectrode
(stainless steel) ~
Extractionlw:Sx*:*>>y&-x-:*>i EleCtTOdC
Ion source
Beam MonitoringElectrode
t 777Faraday Cup
Beam ExtracionSystem
Uniform ElectricField-typeEnergy Analyzer
Iron
Fig.l A schematic diagram of the ion source and energy analyzer
8.0
6.0 -
U 4.0
0.00 2.00 4.00
Energy (eV)
Fig.2 Measured energy spread of H, Beam
6.00
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JAERI-Rcview 95-019
9 . 1 2 Development of a High-precision Beam Profile Monitor
H. Kobayashi, T. Kurihara, T. Urano, T. Suwada, R. Tanaka*,S. Okada*, S. Masuno* and Y. Aoki*National Laboratory for High Energy Physics (KEK), Japan AtomicEnergy Research Institute*
AbstractIt is very important to get a real
image of the beam from the injector linac.Therefore, it is desirable to monitor thebeam position and beam profile as well asthe beam current in the linac. Aluminascreen (Desmarquest AF995R, chromium-activated alumina ceramics ), is often usedas a beam profile monitor for diagnosis of alinac beam. Typical thickness of aluminaphosphor screen is about lmm. Especiallyfor the low energy beam part of the linac,scattered electrons in such a thick screenproduce enlarged beam profiles. A thin filmphosphor screen with chromium ionimplanted alumina has been designed andmanufactured to produce a high-precisionbeam profile monitor.
IntroductionThe demand of a low-emittance
electron linac has increased in these years,for applications such as the free-electronlaser, coherent synchrotron radiation, andothers. It is very important to transport andaccelerate the beam emitted from thecathode with negligible emittance growth.There is some attempt to build up anemittance measurement system for a lowemittance beam*). A plastic scintillator
which is 10 |im thin and has a fastscintillation characteristic has been adoptedto measure the beamlets1 image with a hightemporal and spatial resolution. Silver (30Angstrom thin) was deposited on thescintillator surface by vacuum evaporationto avoid charge-up. This experimental setup is for off-line use. An inorganicscintillator with thin thickness is necessaryfor the injector linac. We try to make aoxide layer on aluminum surface. With ionimplantation technique, we could get apolycrystalline ruby in oxide layer onaluminum surface. As the first trial, wehave made preliminary experiments to showthe possibility to make nearly 10 p.m thinoxide layer on aluminum and to make
polycrystalline ruby layer on alumina withchromium ion implantation technique.
ExperimentalThe aluminum anodizing technique
has been established and is widely applied tometal surface technology to coat or color thesurface of aluminum^.j). We applied thistechnique to produce thin film scintillator.
Aluminum plates of purity 5N wereelectrically polished in a 3N NaOH bath atroom temperature with a dc density of 500
Reactions are as follows,Anode
2A1 + 3H2O -> AI2O3 + 6H+ + 6e-Cathode
6H+ + 6e" -> 3H2The average direct anodic current was fixedat 20 mA/cm^. Thickness of alumina layeras a function of oxidation time is shown inFigure 1.
70
60
"g" 50
a 40
30
20
10
0
c.0
/
/
. . . .
I 1 • • • 1 1 .
>
/
/
/
f
10 20 30 40 50 60 70
Time (min.)
Fig. 1. Thickness of alumina layer as afunction of oxidation time.
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JAERl-Review 95-019
Compared with other method (for example,vacuum evaporation technique or sputteringtechnique), one could easily get a nearly 10|im thin oxide layer with reasonable time bythe aluminum anodizing technique.
Alumina plate of thickness 0.125 mmpurchased from ASAHIKASEI Co. wasprepared as a starting material. Purity ofalumina was 99.9wt.% AI2O3. Specimensize was 20 mm.x 20 mm. Specimens wereimplanted at room temperature with 200keV or 800 keV chromium to fluences in therange 1 X 101 2 /cm2 - 1 x 101 6 /cm2.Chromium ion implantation profiles havebeen generated for alumina using thesimulation code TRIM. Figure 2 shows theimplantation profiles for 10 keV to 1 MeVchromium ion in alumina.
B
Q
Electron
Nuclear
CrOnAI2O3.dot
— o-
- - X -
• • +•
- D
•E
• F
Projected
longiludnStrsgginj
LateralStragging
200
150
X§ 100 k•o
50 -
•
/
/
\
>
/ /
1p
. * • ' '
. . .
\
'I/ •
/ /
r'
• • * ' „ -
r- *
//
/1
-. >
- - • "
•
•
•
•
•
5000
- 4000
- 3000DO
- 2000"
- 1000
0 200 400 600 800 1000 1200
Ion Energy (keV)
Fig. 2. Implantation profile of Cr in AI2O3.
Takasaki Ion Beam Implanter and TandemAccelerator were used for this implantationexperiment.
After implantation, specimens weremounted on the specimen holder of the beam
profile monitor test bench in KEK. Thesespecimens were irradiated with 150 keVelectron beam from the linac. The intensityof the linac beam was measured using thecurrent monitor. The peak current of thebeam was 200 mA. The beam was 5 |ispulse width and lHz repetition rate.Emission from the specimen was taken byCCD camera. Beam test was done by theexperimental set up shown in Fig. 3.
Phosphor Screen
CCD Camera
tZD
Viewing Port
Vac. Gage
Vac. Pump
Fig. 3. A schematic view of a beam profilemonitor test bench.
ResultsOptical measurements were done
with specimens as implanted. Comparedwith Desmarquest AF995R, no lightemission from implanted alumina wasobserved yet. Naramoto et al.4) pointed thatin the temperature range of 1200 °C to 1300°C , substitutional damage recovery hastaken place in both the Al and O sublattices,and at these temperatures, one begins to seesignificant Cr incorporation intosubstitutional lattice sites. Recovery processis necessary to get emission from thisspecimen.
References1) Y. Yamazaki, T. Kurihara, H. Kobayashi,I. Sato and A. Asami, Nucl. Instrum. &Methods in Phys. Res. A322 (1992) 1392) M.Miyagi et al., Applied Optics Vol.26,N0.6, (1987)9703) D.G.W.Goad and M. Moskovits, J. Appl.Phys. 49 (5) (1978)29294) Naramoto et al., J.Appl.Phys. 54 (1983)683
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JAERI-Review 95-019
10. Status of TIARA 1994
10.1 Utilization of TIARA Facilities
Ion Beam Research Administration Division •••• 245
10.2 Operation of AVF Cyclotron
Group of Cyclotron Operation, Ion Accelerator Division 247
10.3 Operation of the Electrostatic Accelerators
Group of Electrostatic Accelerators Operation and
Ion Accelerator Division 248
10.4 Radiation Control and Radioactive Waste Management in TIARA
Safety Division and Utilities and Maintenance Division,
Department of Administrative Services 249
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1 0 . 1
JAERI-Rcview 95-019
UTILIZATION OF TIARA FACILITIES
Utilization and Coordination Division,
Advanced Radiation Technology Center, JAERI
1. Introduction
TIARA is a center of the ion acceleratorfacilities for ion beam applications that iscomposed of three buildings and four ionaccelerators, i.e. an AVF cyclotron, a 3MVtandem accelerator, a 3MV single-endedaccelerator, and a 400kV ion implanter. Thecyclotron and the tandem accelerator have beenserved for research applications since FY1990. The single-ended accelerator and theion implanter were also started for research usein January 1994.
2. Utilization System
TIARA is opened for public use: it receivesapplications of the experimental subjects oncea year from users in wide areas as well asJAERI staffs, and the subjects are approvedafter official investigation by TIARA GeneralProgram Committee(GPC). The utilizationday of each accelerator is fairly allotted to the
subjects three times per year by ProgramAdvisory Committee under the GPC that areboth publicly organized.
Charges for the utilization by visitors areremitted in the case that the outer users haveconcluded a contract of the joint research(between JAERI and a university or acompany) or that of projective joint researchbetween JAERI and universities; the results ofresearch have to be published at the TIARAResearch Review Meeting and in the JAERITIARA Annual report in these cases. There isanother system of visitor use with charges butwithout the publication duty.
3. Experimental subject approved
Number of subjects approved in FY 1994for the experiment using cyclotron was 51 andthat using three electrostatic accelerators was42. Subject numbers in each research field areshown in Table 1, and those in each categoryof relations with users are in Table 2.
Table 1. Number of experimental subjectsat various research fields.
Table 2. Number of experimental subjectsat various relations with users.
^"^.^^^ AcceleratorsFields o t S .Research ^""N^^
Materials for space
Materials for fusion
Biotechnology
Functional material
R I & nuclear chem.
Radiation chemistry
Basic technology
Others
total
number of subjects
cyclotron
6
3
9
9
7
6
9
2
51
clctrostaticaccelerators
3
12
2
18
0
0
6
1
42
^""">»»»^Ni AcceleratorsRelations ^****>»v>>>>^with visitors ^ - - . s ^ ^
JAERIonly
Takasaki Establishment
others
Cooperative rcscaich w\h university
The JAERI-univcrsitics collaborativeresearch program
Joint research with private companyor governmental institute
Cooperative &Joint Researches
Visitors use with charges
total
number of subjects
cyclotron
12
7
12
11
8
1
-
51
electrostaticaccelerators
14
9
9
7
3
0
-
42
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JAERI-Rcvicw 95-019
4. Allotted time to users
Table 3 shows officially allotted time ofaccelerator utilization to every research field ateach period (6-1, 6-2, 6-3) in FY 1994. Table4 also shows the allotted time to ever}' groupclassified with the kinds of users. Theutilization time is allotted to the user by unit ofday; one day means a daytime from 9 a.m. to 6p.m. in case of the electrostatic accelerators.In case of the cyclotron one day means a
daytime (9 a.m. to 6 p.m.) or a night (6 p.m.to 9 a.m.) since the cyclotron has beencontinuously operated from Monday to Friday.
As shown in Table 3, the cyclotron wasused at the various research fields, and theelectrostatic accelerators were mainly used atthe research field of functional material. Theratios of allotted time to JAERI staffs wereca.40% in the cyclotron utilization and ca.70% in the whole utilization of electrostaticaccelerators, ss shown in Table 4.
Table 3. Utilization of accelerators in FY 1994 at various research fields.
^ > v AcceleratorsFields f f ^ ^ s -
Research ^ N .
Materials for space
Materials for fusion
Biotechnology
Functional material
R I & nuclear chem.
Radiation chemistry
Basic technology
Others
total
6-1
15.7
2.0
8.2
5.0
10.0
12.7
22.2
3.3
79
cyclotron
6-2
15.5
1.5
7.0
7.0
9.0
9.0
19.5
2.5
71
6-3
12.7
0
5.8
4.7
8.0
7.7
12.5
1.7
53
total
43.8
3.5
21.0
16.7
27.0
29.4
54.2
7.5
203
utilization days
tandem accelerator
6-1
13
10
4
14
8
0
49
6-2
11
8
4
18
7
0
48
6-3
9
10
2
13
10
0
44
total
33
28
10
45
25
0
141
at each period
single-ended accelerator
6-1
0
13
0
23
7
0
43
6-2
0
17
0
27
11
0
55
6-3
0
14
0
20
8
0
42
total
0
44
0
70
26
0
140
6-1
0
4
0
35
2
0
41
ion implantcr
6-2
0
9
0
30
2
0
41
6-3
0
7
0
31
2
0
40
total
0
20
0
96
6
0
122
Table 4. Utilization of the accelerators in FY 1994 at various relations with users.
^ ^ " • ^ ^ ^ AcceleratorsRelations ^"""^^^^^with visitors ^""""^-v^^
JAERIonly
Takasaki Establishment
others
Cooperative research with university
The JAERI-univcrsities collaborativeresearch program
Joint research with company orgovernmental institute
Cooperative &Joint Researches
Visitors use with charges
total
6-1
24.9
7.0
8.6
26.3
9.8
2.5
1.0
80
cyclotron
6-2
21.3
7.5
7.0
13.8
20.0
1.4
3.0
74
6-3
18.2
5.0
4.4
8.7
15.7
1.0
5.0
58
total
64.4
19.5
20.0
48.8
45.6
4.9
9.0
212
utilization days
tandem accelerator
6-1
19
8
7
4
11
0
49
6-2
19
6
3
10
10
3
51
6-3
19
11
2
3
9
4
48
total
57
25
12
17
30
7
148
at each period
singl-cndcd accclcr.
6-1
23
13
1
6
0
0
43
6-2
29
15
2
9
0
0
55
6-3
20
14
2
6
0
0
42
total
72
42
5
21
0
0
140
6-1
28
4
4
5
0
0
41
ion implantcr
6-2
24
6
8
3
0
3
44
6-3
21
7
4
8
0
0
40
total
73
17
16
16
0
3
125
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JAERI-Review 95-019
1 0 . 2 Operation of AVF Cyclotron
Kazuo ARAKAWA, Yoshiteru NAKAMURA, Watalu YOKOTA,Mitsuhiro FUKUDA, Takayuki NARA, Takashi AGEMATSU,Susumu OKUMURA and Ikuo ISHIBORIAdvanced Radiation Technology Center, JAERI
The JAERI AVF cyclotron was smoothlyoperated according to a beam-time allotmentapproved in program advisory committee.The cyclotron is usually operated weekly.The weekly operation is carried outcontinuously from Monday morning tillFriday evening. Regular yearly over-haulwas carried out for 5 weeks in the summer.
The total operation time in FY 1994 was3068 hours, and monthly operation times areshown in Fig. 1. The percentage of time usedfor experiments, beam developments, andtuning were 83.0%, 6.0% and 11.0%,respectively. The beam time for experimentswas 2555 hours in FY 1994 . Twenty-five
ion species including four new ions, H+ (60,
90 MeV), 16O6+ (160 MeV) and 20Ne8+ (350MeV), were provided for experiments. Theaccelerated particles and their beam time arealso shown in Fig. 2. The beam time forheavy ions exceeded 50% of all as shown in
Fig. 2. A single pulsed beams of 12C5+ (220MeV) ion were also provided for experimentsusing a beam chopping system.
The aluminum rotor wings and stator onesof the turbo-molecular pump were destroyedcompletely. The fine broken pieces ofaluminum were scattered in the ducts of thebeam transport lines. More than 100 hours oftime lost was due to this trouble and we hadto cancel or reschedule the beam time forrepair.
In order to meet the requests from manygroups of researchers, the acceleratedparticles, their energies and the beam courseswere changed as shown in Table 1.
Table 1 Frequency of particle, energy andbeam course change in FY.
FY Particle EnergyBeam
Course1992 42 47 641993 43 51 1231994 70 74 145
350
300 —
4 5 6 7 8 9 10 11 12 1 2 3Month
Q Tuning • Visitors use with charge0 Beam development E l Experiment
Fig. 1 Monthly operation times in FY 1994.
o D96.6H 22.0H
Fig. 2 Beam times of accelerated ions in FY1994.
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JAERI-Rcview 95-019
1 0 . 3 Operation of the Electrostatic Accelerators
S. Tajima, I. Takada, K. Mizuhashi, S. Uno, K. Okoshi.Y. Nakajima,Y. Saito, Y. Ishii
Ion Accelerator Operation DivisionAdvanced Radiation Technology Center, JAERI
The three electrostatic accelerators inTIARA, a 3MV tandem accelerator, a3MV single-ended accelerator and a400kV ion implanter, have been operatedsmoothly in FY 1995. They were utilizedfor various experiments using multipleand single ion beams and electron beams.
Total operation times for eachaccelerator in this fiscal year were 1216hours for the tandem, 1519 hours for thesingle-ended and 1163 hours for theimplanter. Monthly operation times forthree machines are illustrated in Fig.l.
•Tandem•Single Ended
| plmplantef'
4 5 6 7 8 9 10 11 12 1 2 3
Month
Fig. 1 Monthly Operation Times forElectrostatic Accelerators in FY 1994.
Each accelerator provided the variousbeams for the experiments, seventeen ionspecies from the tandem, three ionspecies and electrons from the single-ended and twenty two ion species fromthe implanter. The percentages ofacceleration days of ion species areshown in Fig.2 for each accelerator.
Five new ion beams for B, P, Mn, Cnand Sin were newly accelerated by usingthe SNICS ion source for the tandem.(Cn, Sin: molecular ions). Althoughacceleration of the molecular ions weredifficult because they were easily brokenin the stripper canal, we succeeded inacceleration of C2-C8 and Si2-Si4 at6MeV. The details are reported in aseparate paragraph in this chapter.
Thirteen new ion beams for N, Ne,Mg, Al, Cl, Ti, Cr, Fe, V, Nb, La, Wand Bi were also newly accelerated byusing the Freeman ion source for theimplanter. Metal ions such as Cr, Fe andLa were generated from their chloridesusing oven and refractory metal ions suchas Nb and W were produced by filamentsmade of themselves.
The regular maintenance of theaccelerators were carried out in April,August and December. A worn out shaftof the chain pulley of the tandem wasreplaced with new one in August. Inorder to supply the electron beam usingthe single-ended machine, polaritychange of the high-voltage generationcircuit with tank opening were carried outfour times, in April, July, September andMarch.
Tandem
Single-ended
Implanter
Fig. 2 Percentages of Acceleration Daysof Ion Species for ElectrostaticAccelerators in FY 1994.
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JAERI-Review 95-019
1 0 . 4 RADIATION CONTROL & RADIOACTIVE WASTE MANAGEMENT IN TIARA
Safety Division S Uti l i t ies and Maintenance Division,
Department of Adminis t ra t ive Services , TRCRE, JAERI
1. Radiation Control
1.1 Individual monitoring(1) Individual monitoring fo r t h e r a d i a -tion workersTable 1 shows a distribution on effec-
tive dose equivalent of the radiationworkers in fiscal 1994. The effectivedose equivalent of all workers exceptfour were less than 0.2 mSv (minimumdetectable dose equivalent) and theall workers were under 1 mSv.
(2) Individual monitoring for the in-spect visitors etc. to the radiationcontrolled areasTable 2 shows number of persons who
have been entered the controlled areastemporally except the radiation workersresisted officially. Individual moni-toring for these persons were carriedout with TLD and the effective doseequivalent of every entrance person wasless than minimum detectable dose.
Table 1. Distributions on the effective dose equivalent in fiscal 1994.
Items
Distribution range
on effective dose
equivalent
HE: Effective dose
equivalent
(mSv)
Persons
~"~ -~-~^^Per i ods
HE £ 0.2
0.2 < HE £ 1.0
1.0 < HE £ 5.0
5.0 < HE £ 15.0
15.0 < HE £ 25.0
25.0 < HE S 50.0
50.0 < HE
Persons for radiation control (A)
Exposure
above 1 mSv
Persons (B)
(B)/(A) X100 (%)
Mass effective dose equivalent (nan raSv)
Mean dose equivalent (mSv)
Maximum dose equivalent (mSv)
Number of persons
1stquarter
387
0
0
0
0
0
0
387
0
0
0
0
0
2ndquarter
428
1*
0
0
0
0
0
429
0
0
0.4
0.0
0.4
3rdquarter
424
0
0
0
0
0
0
424
0
0
0
0
0
4thquarter
457
3*
0
0
0
0
0
460
0
0
1.1
0.0
0.5
* The same worker was exposed during 2nd 8 4th quarter.
Table 2. Number of temporary entrance persons to radiation controlled areasin fiscal 1994.
-~-— Persons
^"~~-^^^ Periodsentrance persons "-—^
Temporary Workers
Inspect Visitors
Number of persons
1stquarter
235
341
2ndquarter
257
384
3rdquarter
225
455
4thquarter
341
433
total
1058
1613
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JAERI-Review 95-019
1.2 Monitoring of released radioactivi-ties for gas and dustTable 3 shows the maximum radioactive
concentrations and total activities forgas and dust released from TIARA's
stack, during each quarter of fiscal1994. The least amount of 41Ar and1 ' C were detected for some time onoperation of cyclotron, but the radio-active dust released was not detected.
Table 3. Monitoring results of released activities for gas and dust in fiscal 1994.Nuclidc
gross- (3
B5Zn
«'Ar
"C
~~ Peri odsItems ——.
dust(Bq/cm3)
dust(Bq/cm3)
maximumconcentration
maximumconcentration
Total releasedactivity (Bq)
gaseous(Bq/cm3)
maximumconcentration
Total releasedactivity (Bq)
gaseous(Bq/cm3)
maximumconcentration
Total releasedactivity (Bq)
1stquarter
<5.5X 1 0 - "
<3.7x10"1 0
0
<2.0X10"1
1.2x 10s
-
-
2ndquarter
<5.5xl(T"
<4.4xlO"10
0
<2.0xlO'5
0
-
-
3rdquarter
<5.3X10-"
<4.2x 10-10
0
<2.0X10"4
3.4x 108
-
-
4thquarter
<5.3X10"11
<9.8X10"12
0
<1.2X10-1
2.7X108
1.7X10-*
5.3xlO8
total
<5.5xlO""
<4.4xlO"10
0
<2.0X10-"
7.3xlO8
<1.7xlO-
5.3XlO8
1.3 Monitoring for radiation dose rateand surface contaminationRadiation dose rate monitoring was
routinely carried out in/around thecontrolled areas and surface contami-nation monitoring was also carried out.
No unusual value of dose rate or con-tamination was detected. Figure 1displays a distribution of the doserate at the controlled area in thecyclotron building as an example.
" ,r
Fig. 1Dose rate distribution at theradiation controlled area inthe cyclotron building.
Date measured :March 22, 1995
Measuring position :Indicated with xabove 1 m from floor
Unit : M Sv/h(numerics less than 0.2fi Sv/h are not indicated)
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JAERI-Rcvicw 95-019
1.4 Authorized radioisotopesTable 4 (a) shows a list of sealed
radioisotopes authorized at the end offiscal 1994. These isotopes are used inTIARA as checking sources for several
kinds of radiation detectors. Eighteennuclides of unsealed type are also au-thorized mainly for researches of neu-tron shielding and RI production, asshown in Table 4(b).
Table 4. List of radioisotopes authorized at the end of fiscal 1994 in TIARA,(a) Sealed radioisotopes
AuthorizationNo. and Date
No.6415
Jan. 30. 1995
Nuclides andAmounts
24IAm3.7 GBq X I
22Na370 MBq xl3.7 GBq XI
57Co
370 MBq X4• i o » S n
370 MBq X 4
Places Used
Cyclotron BuildingLight Ion Room 1 to 3Heavy Ion Room 1 to 3Cyclotron VaultLight Ion Preparation RoonHeavy Ion Preparation RoomHeavy Ion Measuring Room
Multiple Beam BuildingTarget Room 1Tandem Accelerator Room
Ion Beam Research BuildingHot Sample Testing Room
Electron Accelerator-1 BuildingVertical Beam Experimental Roon
Cyclotron BuildingISOL Roon
Ion Beam Research BuildingHot Physics Laboratory
Place of Strage
Cyclotron Building
Electron Accelerator-1BuildingRI storage box inVert.B.Exper.Room
Cyclotron BuildingRI storage box inISOL Room
(b) Unsealed radioisotopes
AuthorizationNo. and Date
No.4257
Sept.22. 1994
Places Used
Cyclotron BuildingLight Ion Rooms 1 to 3Cyclotron VaultCyclotron Pit RoomSwitching Magnet RoomCooling RoomPower Distribution RoomHot Work RoomHot LaboratorySemi Hot LaboratoryRI Measuring RoomISOL Room
Ion Beam Research BuildingRadiation Measuring ROODHot Physics LaboratoryHot Work RoomHot Chemical Laboratories 1 to 2
Nuclides andAmounts of Annual Use
54Mn05Zn56Co55Fe7Be
75Se95 T o130CellCI3 N
• 5Q
5EFe6lCu
133Xe""Re
1Z7Pri"Pr
50 MBq1 GBq1 GBq
500 MBq1 GBq
200 MBq200 MBq600 MBq
4 GBq4 GBq4 GBq
200 MBq200 MBq300 MBq600 MBq4 GBq3 MBq3 MBq
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JAERi-Review 95-019
2. Radioactive Waste Management
2.1 Solid wastesTable 5 shows the amounts of solid
wastes at various properties and kindsgenerated in each quarter of fiscal1994. Main wastes were combustiblematter such as gloves and incombusti-ble filters for exhaust air. Com-pressible wastes were generated mainlyby the cyclotron maintenance.
2.2 Liquid wasteLiquid waste was almost waste water
('inorganic' in Table 6) generated withchemical experiments and operation ofair conditioning units installed in
each room of the first class radiationcontrolled area. Larger quantity ofthe waste water in summer season (2ndquarter) are mainly due to condenseddrain from air by operating the units.
Low level waste water is treated byevaporation and condensed water is re-used in the controlled area. Only smallammounts of residue are generated bythe evaporation because the radiationlevel is very low and the waste qualityis very pure so that the waste can beevaporated to high concentration rate.
The evaporation residue and sludge aresolidified by cement in a stainless steeldrum. The residue and sludge of ca. 100liter makes one cement solidify of 200liter drum.
Table 5. Radioactive solid wastes generated in fiscal 1994.
^v'~"~~- AmountsItems ^^-^^^
Low level
1)Combustible
2)Incombustible
Compressible
Filters
I incompressible
Ion exchange resin
Cement solidify
High level
1)Incombustible
Amounts of generation in each periods On3)
1stquarter
0.32
0.32
0
0
0
0
0
0
0
0
2ndquarter
0.90
0.80
0.10
0.10
0
0
0
0
0
0
3rdquarter
0.12
0.12
0
0
0
0
0
0
0
0
4thquarter
1.38
0.56
0.82
0.10
0.72
0
0
0.40
0
0
total
2.72
1.80
0.92
0.20
0.72
0
0
0.40
0
0
Numberof
package/drum
12*
0
7
2*
0
0
* : 200 liter drum
Table 6. Radioactive liquid waste generated in fiscal 1994.
^^•^-^ AmountsItems ^ ^ ^ ^
Low level
1)Inorganic
2)0rganic
Organic
Oil
3)Sludge
Medium level
1)Inorganic
2)0rganic
Organic
Oil
3)Sludge
Evaporation residue
Amounts of generation in each periods (m3)
1stquarter
10.29
10.29
0
0
0
0
0
0
0
0
0
0
0
2ndquarter
18.72
18.72
0
0
0
0
0
0
0
0h d
0
0
3rdouarter
9.41
9.41
0
0
0
0
0
0
0
0
0
0
0
4thquarter
8.33
8.33
0
0
0
0
0
0
0
0
0
0
0.20
total
46.75
46.75
0
0
0
0
0
0
0
0
0
0
0.20
Numberof
package/drum
treatment
0
0
0
*
*: treated to cement solidify
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JAERl-Review 95-019
Appendix
Appendix 1. List of Publications 255
Al .1 Publications in Journal 255
Al .2 Publications in Proceedings 258
Appendix 2. Type of Research Collaborations 263
Appendix 3 . Organization and Personnel of TIARA 264
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JAERI-Review 95-019
Appendix 1. LIST OF PUBLICATIONS
Al. l . Publications in Journal
P.R.Okamoto JO 7JO 1. H.Abe, C.Kinosita,and L.E.RehnEffect of concurrent irradiationwith electrons on ion-inducedamorphization in siliconJ. Nucl. Mat. 212-5 (1994) 298.0 5.15 42032
J02. H.Abe and C.KinositaEffect of concurrent irradiationwith ions and electrons in Si andGe and their in-situ observationsIONICS 20(7) (1994) 39.(in Japanese)0 5.15 42032
J03. T.Asakawa and H.KoimumaWhat applications of fullerene?Kagaku (6) (1995) 30.(in Japanese)1 5.13 42028
J04. T.Asakawa, M.Sasaki, M.Yoshimoto,S.Gonda, T.Shiraishi and H.KoimumaElectrical Properties of C6o andits partially decomposed thin filmsfabricated by vacuum evaporationand ion plating methodsMat. Res. Soc. Symp. Proc. 349(1994) 185.I 5.13 42028
J05. T. Hirao and I. NashiyamaApplication of heavy-ion micro-beams - Single-events in LSIs forspace —Radiation Chemistry No.58 (1994)37. (in Japanese)T 1.2 42001
J06.T.Hirao, I.Nashiyama, T.Kamiya andT.NishijimaEffects of micro-beam induceddamage on single-event currentmeasurementsNucl. Instrum. Meth. B (1995)(in press.)T 1.2 42001
H.Kageyama, K.Kawatsura,R.Takahashi, T.Awata, T.Nakae,S.Arai, K.Kambara, M.Oura,T.Papp, Y.Kanai, Y.Awaya,T.Takeshita, Y.Aoki, S.Yamamoto,P.Goppelt-Langer, H.Naramoto,Y.Horino, Y.Mokuno and K.FujiiL X-ray spectra of Fe and Cu by0.75 MeV/u H, He. Si and Ar ionimpactsNucl. Instrum. Meth. B(submitted for publication).S 6.5/6.6 42019
J08. K.Kawatsura, T.Nakae, R.Takahashi,Y.Nakai, S.Arai, S.Yamamoto,T.Takeshita, P. Goppelt-Langer,H.Naramoto, Y.Horino, Y.Mokuno,K.Fujii, T. Mitamura, M.Terasawa,H.Uchida and K.KoterazawaAnalysis of radiation-inducedsegregation in type 304 stainlesssteel by PIXE and RBS channelngNucl. Instrum. Meth. B(submitted for publication).S 6.5/6.6 42019
J09.Y.Kido, T.Nishimura, Y.Furukawa,Y.Nakayama, T.Yasue, T.Koshikawa,P.Goppelt-Langer, S.Yamamoto,H.Naramoto and T.UedaSolid-phase epitaxitial growth ofGe on H-terminated and oxidizedSi(100) surfacesSurface Sciences 327 (1995) 225.S.T 6.7 42020
J10. CKinositaEffects of irradiation on ceramicsand their special featuresMateria Japan 33 (1994) 1351.(in Japanese)I 5.17 42035
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JAERI-Rcview 95-019
J l l . C.Kinosita, H.Abe, S.Maeda andK.FukumotoEffect of concurrent irradiationwith ions and electrons on theformation process of defectscrusters in covalent and ioniccrystalsJ. Nucl. Mat. 219 (1994) 152.0 5.15/5.17 42032/42035
J12. H.Koimuma and T.ArakaneSynthesis and thin-film formationof globular nano-molecule Ce oDennsi-joho Tushin Gakukaishi 77(1994) 1161 (in Japanese).1 5.13 42028
J13. V.V.Krushev, H.Koizumi,T.Ichikawa, H.Yoshida, H.Shibata,S.Tagawa and Y.YoshidaRelation between track structureand LET effect on free radicalformation for ion beam-irradiatedalanine dosimeterRadiat. Phy. Chem., 44 (1994) 521T.S.0 6.4 42018
J14.H.Kudo, T.Fukusho, T.Ishihara,H.Takeshita, Y.Aoki, S.Yamamotoand H.NaramotoCharge states of fast ions inglancing collisions with alignedatoms in Si crystalsPhys. Rev. A50 (1994) 4049.T.S.O 6.4 42018
Shima, T.Ishihara,S.Yamamoto and
J15.H.Kudo, K.H.Takeshita,H.NaramotoHigh-energy shadowing effect andits application to atomic andsolid stste physics.Nucl. Instrum. Meth. B90 (1994)533.T.S.O 6.4 42018
J16. A.MiyashitaTime- and space-resolving softX-ray absorption spectroscopy oflaser produced plasmaOyo Buturi 64 (1995) 592.(in Japanese)0 6.1? off-line
J17. T.Ohyanagi, A.Miyashita, K.MurakamiObservation of the initial stageof the laser ablationIONICS 20(7) (1994) 29.(in Japanese)0 6.17 off-line
J18.T.Nakae, K.Kawatsura, R.Takahashi,S.Arai, T.Mitamura, M.Terasawa,H.Uchida, K.Koterazawa, Y.Horino,Y.Mokuno and K.FujiiCharacterization of single crystalof type 304 stainless using RBS-and PIXI-channelingJ. Nucl. Mater. 223 (1995) 210.S 6.5/6.6 42019
J19.T.Nakae, R.Takahashi, T.Nomura,Y.Nakai, H.Kageyama, N.Shimatani,T.Awata, A.Nishihata, S.Arai,K.Kawatsura, Y.Horino, Y.Mokuno,K.Fujii, Y.Aoki, T.Takeshita,S.Yamamoto, P.Goppelt-Langer,H.Naramoto, T.Mitamura,M.Terasawa, H.Uchida andK.KoterazawaApplication of PIXE- and RBS-channeling to investigations on thecharacterization of single crystalstainless steelInt. J. PIXE 4 (1994) 193.S 6.5/6.6 42019
J20. T.Nakano, K.Okaichi, K.Harada,H.Matsumoto, R.Kimura,K.Yamamoto, S.Akasaka andT.OhnishiMutations of a shuttle vectorplasmid, pZ189, in Escherichiacoli induced by boron neutroncaptured beam(BNCB) containinga -particlesMutation Res., DNA Repair, 336(1995)153.C 2.9 41016 :
J21 . H. NambaRadiation chemistry with heavy ionbeamsRadioisotopes 44 (1995) 69.(in Japanese)C 3.6 41038
- 2 5 6 -
JAERl-Revicw 95-019
J22.H.0hno, Y.Aoki and S.NagaiLow-energy ion-beam depositionapparatus equipped with surfaceanalysis systemJAERI-Research 94-018 (1994)0 6.19 off-line
J23. T.Ohnuki, T.Sato, H.Isobe andT.MurakamiRedistribution of strontium andcesium during alteration ofsmectite to illiteRadiochimica Acta, 66/67 (1994)323.0 6.15 42041
J24. A.Osa, M.Asai, M.Koizumi,T.Sekine, S.Ichikawa, Y.Kojima,H.Yamamoto and K.Kawade/3 + Decay of unstable praseo-dymium isotopes: 1 2 7Pr, | 2 B p rand the new isotope l z 5 p rNucl. Phys. A588 (1995) 185c.C 7.2 41033/41034
J25.S.Seki, M.Ando, T.Yamaki,Y.Nakashiba, K.Asai, K.Ishgure,and S.TagawaMolecular interaction inLangmuir-Blodgett films ofamphiphilic polysilanesJ.Photopolym.Sci.Technol. (1995)8, 89.C 3.2 41036
J26.S.Seki, H.Shibata, Y.Yoshida,K.Ishgure and S.TagawaRadiation effects on hole driftmobility in polysilanesRad.Phys.Chem. (1995) in press.C 3.2 41036
J27.S.Seki, S.Tagawa, K.Ishgure,C.R.Cromack and A.D.TrifunacObservation of silyl radiacalin y -radiolysis of solidpoly (dimethylsilane)Rad.Phys.Chem. (1995) in press.C 3.2 41036
J28. N.Shigeta, H.Matsuoka, A.Osa,M.Koizumi, M.Izumo, K.Kobayashi,K.Hashimoto, T.Sekine andR.M.LambrechtTantalum-183 : Cyclotronproduction of a neutron-richbiomedical tracerAppl.Rad.Isotopes (in press)C 7.2 41033
J29. N.Shigeta, H.Matsuoka, A.Osa,M.Koizumi, M.Izumo, K.Kobayashi,K.Hashimoto, T.Sekine andR.M.LambrechtProduction method of no-carrier-added I 8 8ReJ.Radioanal.Nucl.Chem. (in press)C 7.2 41033
J30.K.Shin, K.Miyahara, E.Tanabeand UwaminoThick-target neutron yield forcharged particlesNucl. Sci. S Eng. 120 (1995) 40.0 8.2 41045
J31. S.Yamaguchi, K.Takahiro, Y.Hujino,H.Naramoto and K.OzawaAn ion channeling study on V2DcrystalsJ. Alloys and Compounds (1995)(in press.)S 6.10 42022
J32. K.Yasuda, Y.Watanuki, C.Kinoshitaand H.AbeMicrostructure evolution inmagnesium aluminate spinelunder displacive and ionizingirradiation [ 1 ]Annual Reports HVEMLAB. KushuUniv. No.19 (1995) 11.1 5.17 42035
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JAERI-Review 95-019
A1.2. Publications in Proceedings
CO I.H.Abe, C.Kinoshita and Y.DendaStability of cascades under ionand electron irradiation in germa-niumMaterials Research Society Sympo-sium Proceedings 373 (1995) p.487.0 5.15 42032
C02. H.Abe, H.Naramoto and C.KinoshitaAmorphization of graphite under ionor electron irradiationMaterials Research Society Sympo-sium Proceedings 373 (1995) p.383.1 5.15 42032
C03. K.Adachi, T.Fujimura, H.Omichi,H.Watanabe, M.Fukawa, M.Takoi,H.Kobayashi and M.TamuraGamma-ray and ion-beam irradia-tion effect on animal red-bloodcellsProc. 37th Symp. Radial Chem.(Sapporo, Sept.26-28, 1994) p.129C 2.10 41051
C04. K.Adaci.i, T.Fujimura, H.Omichi,H.Watanabe, M.Takoi, M.Fukawa,H.Kobayashi and M.TamuraIon irradiation effect on animalred-blood cellsProc. 37 th Ann. Meeting of JapanRadiation Research Soc. (Fukuoka,Oct.27-29, 1994) p.142C 2.10 41051
C05. T.Agematsu, S.Okumura andK.ArakawaUniform irradiation of high-energy,intense ion beams to large area bytwo-dimensional beam scanningProc. 6 th Japan-China BilateralSymp. Radiat. Chem. (Tokyo, Nov.6-11, 1994), JAERI-Conf 95-003 p.467.C 9.2 Acc.Op.
C06.M.Asai, Y.Kojima, A.Osa, M.Koizumi,T.Sekine, M.Shibata, H.Yamamoto andK.KawadeLow-spin level structure of 1Z6Bainvestigated by y - y angular cor-relation measurementProc. Int. Conf. on Exotic Nuclei
and Atomic Masses (ENAM95)(Arle, France, Junel9-23, 1995)(in press)C 7.2 41033
C07.S.Baba, M.Ishihara and M.EtoProton irradiation effects onmechanical strength of carbon/carbon composites1994 Fall Meeting of the AtomicEnergy Soc. of Japan (Sapporo,Sept.28-30, 1994) p.185.C 5.04 41007
C08. M.Fukuda, S.Okumura, K.Arakawaand T.KarasawaExternal beam phase width mea-surements a t JAERI AVF CyclotronProc. 4 th European Particle Ac-celerator Conf. EPAC94 (London,June27-Julyl, 1994) p.548.C 9.2 Acc.Op.
C09. P.Goppelt-Langer, S.Yamamoto,Y.Aoki, H.Takeshita and H.NaramotoLight and heavy element profilingusing heavy ion beams12nd Int. Conf. Ion Beam Analysis(Arizona, May 22-26, 1995)(accepted for publication)T 6.8/6.9 42021
C10. P.Goppelt-Langer, S.Yamamoto,Y.Aoki, H.Takeshita and H.NaramotoStopping powers and straggling of15 N ions for nuclear reactionanalysis at 6.385 MeV12nd Int. Conf. Ion Beam Analysis(Arizona, May 22-26, 1995)(accepted for publication)T 6.9 42021
Cll.Y.Hama, K.Hamanaka, H.Matsumoto,H.Kudoh, T.Sasuga and T.SeguchiInhomogeneous degradation ofpolymers irradiated by X-rays,gamma-rays and ion-beam asstudied by micro-FT-IRProc. 9 th Int. Meeting on Radiat.Processing (IMRAP-9), (Istanbul,Sept.11-16, 1994) to be published.C 3.1 41035
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JAERI-Rcvicw 95-019
C12. Y.Hama, K.Hamanaka, H.Matsumoto,H.Kudoh, T.Sasuga and T.SeguchiRelationship between energy pro-file and chemical structuralchanges in polymers irradiated byion-beamsProc. 6 th Japan-China BilateralSymp. Radiat. Chem.(Tokyo, Nov.6-11, 1994), JAERl-Conf 95-003p.101.C 3.1 41035
C13. S.Hamada, Y.Miwa, D.Yamaki andY.ZhangDevelopment of triple-beam irradi-ation facilityAbstract of the Japan Institute ofMetals, Fall Meeting (Fukuoka, Oct.8-10, 1994)T.S.I 5.5 42008
C14. S.Hamada, Y.Zhang, Y.Miwa andD.YamakiMicrostructure of stainless steelirradiated with dual beamsAbstract of the Japan Institute ofMetals, Spring Meeting (Tokyo, Apr.4-6, 1995)T.S.I 5.5 42008
C15. T.Hirao, H.Itoh, I.Nashiyama,I.Naito and S.MatsudaStudy of single-event effect atJAERI TakasakiProc. BEAMS 1994 (Tokyo, Nov.1994) p.31.C,T 1.1/1.2 41005/42001
C16. H.Ichikawa, H.Nakamura andA.NagataniIoslation of photomorphogenic mu-tants in Arabidopsis which promotetransduction of light-signalPlant Cell Physiol. 36(supplement),(1995) p.113.C 2.6 41017
C17. J.Isoya. H.Kanda and Y.MoritaESR studies of point defects insynthetic diamond crystals.Advances in New Diamond Scienceand Technology (Proc. 4th Int. Conf.on New Diamond Science and Tech-nology, Kobe, July 1994) p.351C 1.8 41020
C18. T.Kamiya, T.Suda and R.TanakaSub-micron microbeam apparatususing a single-ended acceleratorwith high voltage stability.Proc. 4 th Int. Conf. on Nucl.Microprobe Technology andApplications(Shanghai, Oct.10-14. 1994)Nucl. Inst. and Meth B(submitted)S 9.7 42038
C19. T.Kamiya, T.Suda and R.TanakaSub-micron microbeam apparatusfor high resolution materialsanalysis voltage stability.Proc. 12th Int. Conf. on Ion BeamAnalysis (Tempe, USA, May 22-26,1995), Nucl. Inst. and Meth B(submitted)S 9.7 42038
C20. T.Kamiya, T.Suda and R.TanakaHigh energy single ion hit systemcombined with heavy ion micro-beam apparatusProc. 12th Int. Conf. on Ion BeamAnalysis (Tempe, USA, May 22-26,1995), Nucl. Inst. and Meth B(submitted)T 9.6 42037
C21. K.Koizumi, T.Sekine, A.Osa andT.HoriguchiDevelopment of a laser ion sourcefor the TIARA-ISOLProc. 6 th Int. Symp. on AdvancedNuclear Energy Research —Innovative Laser Technologies inNucl. Energy (Mito, March 23-25,1994) JAERI-Conf 95-005 p.3580 7.4 off-line
C22.H.Kudo, A.Tanabe, T.Ishihara,S.Seki, Y.Aoki, S.Yamamoto,P.Goppelt-Langer, H.Takeshitaand H.NaramotoCharge states of fast heavy ionsglancing collisions with alignedatoms in single crystalsProc. 16th Int. Conf. Atomic Col-lisions in Solids (Linz, Austria,1995).S.O 6.4 42018
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C23. K.Kuriyama, T.Kato, K.Tomizawa,Y.Takahashi, A.Aoki, H.Takeshita,S.Yamamoto and H.NaramotoElectrical activation process of Cimplanted semi- insulating GaAsProc. 9 th Int. Conf. on Ion BeamModification of Materials (IBMM'95,Canberra, Feb.4-10, 1995)(in press)T 6.14 42030
C24. A.Miyashita, T.Ohyanagi, O.Yodaand K.MurakamiDiagnosis of laser ablated carbonparticles measured by time-resolv-ed X-ray absorption spectroscopyProc. 6th Int. Symp. on AdvancedNuclear Energy (Mito, March 23-25, 1994) p.873.0 6.18 off-line
C25. A.Miyashita, T.Ohyanagi, O.Yodaand K.MurakamiDynamic observation of laser abla-ted carbon particles using time-resolved X-ray absorption spectro-scopyProc. 7th Int. Symp. on Small Par-ticles and Inorganic Clusters(ISSPIC7, Kobe, 1994).(to be published)0 6.17 off-line
C26. T.Nakamura, T.S.Soewarsono, Y.Uno,N.Nakao, Y.Uwamino, M.Imamura,T.Ishikawa, Sh.Tanaka, H.Nakashima,Su.Tanaka, M.Baba and T.IwasakiDevelopment of p~Li quasi-mono-energetic neutron field between 20and 90 MeV for cross section andshielding experimentsProc. 8 th Int. Conf. on RadiationShielding (Arlington, Texas, Apr.24-28, 1994) p.264.C 8.4 41047
C27. T.Nara, W.Yokota, K.Arakawa, M.Ideand Y.KamimuraPreparation of ceramic rods and iongeneration tests for OCTOPUSProc. INS Workshop on ECR IonSources for Multiply-ChargedHeavy Ions (Tokyo, Dec.1-2, 1994)p.45.0 9.3 Acc.Op.
C28. H.Naramoto, H.Takeshita, Y.Aoki,S.Yamamoto, P.Goppelt-Langer andH.AbeMaterials research using ionbeams at TIARA10th Symp. on Surface ProcessingUsing Ion Beams (Tokyo, Nov.24,1994).I.S 6.10 42022
C29.S.Nasu, S.Oonishi, K.Nishiwaki,R.Fujimori, H.Nanto, R.Yamamoto,H.Takeshita, Y.Aoki, S.Yamamotoand H.NaramotoRadiation damages in synthesizedsilica glasses induced by highenergy Fe ions irradiation3rd Int. Symp. on Swift Heavy Ionsin Matter (SHIM-95) (Caen, France,May 15-19, 1995)T 5.14 42029
C30.H.Ohno, Y.Aoki and S.NagaiGrowth of carbon film by lowenergy ion beam depositionProc. 37 th Symp. on RadiationChem. (Sapporo, Sept.26-28,1994) p.187.0 6.19 off-line
C31.H.Ohno, Y.Aoki and S.NagaiStudies on carbon thin film growthby low energy ion beam depositionProc. 5th Symp. on BeamEngineering of Advanced MaterialSyntheses (Tokyo, Nov.21-22,1994) p.147.0 6.19 off-line
C32. T.Ohyanagi, A.Miyashita, K.Murakamiand O.YodaDynamic behaviors of laser-ablated Si particles.Proc. of the Internat. Symposiumon Advanced Nuclear Research(Mito, Mar.23-25, 1994) p.881.0 6.18 off-line
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C33
C34.
S.Okumura, M.Fukuda, W.Yokota,Y.Nakamura, T.Nara, T.Agematsu,I.Ishiboro and K.ArakawaThe beam diagnostic system forJAERI AVF cyclotronProc. 4 th European ParticleAccelerator Conference (London,Jun.27- Jul . l , 1994) p.1518.C 9.2 Acc.Op.
C38.
S.Sasaki, A.Ushirokawa,and M.TanakaInvestigation of solarsolar power satelliteProc. 19 th Int. Symp.Technology and Science
Y.Morita C39
cells forSPS 2000on Space
(Yokohama,May 15-24, 1994) p.29.C 1.5 41002
C35. N.SekimuraPrimary knock-on atom energy de-pendence of cascade damage for-mation and interactionto be presented in ICFRM-7;to be published inJ. Nucl. Mater.T 5.8 42011
C36. N.Sekimura, Y.Kanzaki, N.Ohtake,J.Saeki, Y.Shirao, S.Ishino,T.Iwata, A.Iwase and R.TanakaHigh energy cascades as studied byhigh energy self- ion irradiationto be presented in ICFRM-7;to be published inJ. Nucl. Mater.T 5.8 42011
C37. T.Sekine, M.Izumo, H.Matsuoka,K.Kobayashi, N.Shigeta, A.Osa,M.Koizumi, S.Motoishi, K.Hashimoto,Y.Hatsukawa, F.Miura, T.Sorita,T.Moriya, H.Kudo, H.Umezawaand H.WatanabeA new radioisotope-productionresearch facility utilizing ionbeams from AVF cyclotronProc. 5th Int. Workshop onTargetry and Target Chemistry(BNL, New York, Sep.19-23, 1993)p.347.C 7.2 41033/41034
C40
N.Shikazono, Y.Yokota, A.Tanaka,H.Watanabe and S.TanoIon-beam induced mutations inArabidopsis thaliana.Proc. 1st Symp. of AdvancedScience Research Center(Tokai-mura, Mar.23-24, 1995)P.91.C 2.2 41011
N.Shimatani,R.Takahashi,S.Yamamoto,H.Naramoto,and K.FujiiRadiation- inducedrecrystallizationa -SiC by MeVimplantationProc. 6 th Int. Conf. SiC andRelated Materials (Kyoto, Sept.18-21, 1995)T,S 6.5/6.6 42019
K.Kawatsura,S.Arai, Y.Aoki,
H.Takeshita,Y.Horino, Y.Mokuno
damage andof amorphous
Ni and Au
S.Tajima, I.Takada,S.Uno, Y.Saito,Y.Nakajima, Y.IshiiT.SasugaStatus offacility ofProc. 7thAccelerator
K.Mizuhashi,K.Okoshi,and
beamion multipleTIARA
Workshop on Tandemand Technology
(Tokyo, June 28-29, 1994)p.13.
0 9.8-9.10/10.3 42039/Acc.0p.
C41. A.TanakaBiological studies by use of ionbeams: the effects of ion beams onthe plant and the penetrationcontrolled irradiation techniqueProc. 3rd Symp. Nucl. Res. Center,Tokyo Univ. (Dec.5-6, 1994)C,T 2.1/2.2 42016/41011
C42. A.Tanaka, Y.Yokota, N.Shikazono,H.Watanabe and S.TanoEffects of ion-beams onArabidopsis thaliana.Proc. 10th Int. Cong. Radat. Res.(Wurzburg, Germany, Aug.27-Sept.1, 1995) (to be published)C 2.2 41011
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C43. A.Tanaka, Y.Yokota, H.Watanabe,N.Shikazono and S.TanoBiological effects of heavy chargedparticles in Arabidopsis thaliana.Proc. 5th Workshop on HeavyCharged Particles in Biology andMedicine (GSI, Darmstadt, Germany,Aug.23-25, 1995)(to be published)C 2.2 41011
C44. Tanimoto, H.Mizubayashi andS.OkudaAnelastic study of Mo and W afterlow-temperature irradiationProc. 1st Int. Conf. Ultra HighBase Metals (Kitakyushu, May 24-27, 1994) p.359.S 5.03 42007
C45. Tanimoto, H.Mizubayashi andS.OkudaInternal friction measurements ofMo and W after low-temperatureirradiationProc. 1st Symp. of AdvancedScience Research Center(Tokai-mura, Mar.23-24, 1995)p.57.S 5.03 42007
C46. S.Uno, S.Tajima, I.Takada,K.Mizuhashi, K.Okoshi, T.Sasuga,Y.Kubota and K.KonoControl system for new electro-static Accelerators of TIARAProc. 7th Workshop on TandemAccelerator and Technology(Tokyo, June 28-29, 1994)p.63.
0 10.03 Acc.Op.
C47. S.Yamamoto, P.Goppelt-Langer,Y.Aoki, H.Takesita, H.NaramotoAnalysis of hydrogen in Nb/Cumultilayers using ion beam methods116th Spring Meeting, the JapanInstitute of Metals (Tokyo, Apr.4-6, 1995) p.366.T 6.12 42025
C48. S.Yamamoto, P.Goppelt-Langer,H.Naramoto, Y.Aoki, H.TakesitaAnalysis of hydrogen in Nb/Cumultilayers using ion beamsProc. Int. Symp. Metal-HydrogenSystem (Fuji-Yoshida, Nov.6-11,1994)T 6.12 42025
C49. Y.Yamamoto, O.Kawasaki, S.Matsudaand Y.MoritaRadiation effects of solar cellsfor space use4 th European Space Power Conf.(Poitiers, France, Sep.4-8, 1995)C.T 1.4 41006/42003
C50. W.Yokota, Y.Wu, Y.Saito, Y.Ishii,T.Nara and K.ArakawaConstruction and test operation ofJAERI 18GHz ECR ion sourceProc. INS Workshop on ECR IonSources for Multiply-ChargedHeavy Ions (Tokyo, Dec.1-2, 1994)p.84.0 9.3/9.4 Acc.Op.
- 2 6 2 -
JAERI-Review 95-019
Appendix 2. Type of Research Collaborations
Sectionof thisReport
1.11.21.31.41.51.61.71.8
2.12.22.32.42.52.62.72.82.92.10
3.13.23.33.43.53.63.7
4.14.24.3
5.15.25.35.45.55.65.75.85.95.105.115.125.13
ResearchProgramNumber
41005420014100441006/4200341002410034101941020
4201641011410134101441015/420174101741050410124101641051
41035410364103741039410404103841043
410014200241025
42004 - 6420064200741007420084200942010420114201241021420244202642028
Type ofResearch
Collaborations*
Joint Res.Joint Res.(JAERI)
Joint Res.Joint Res.(JAERI)
Joint Res.Coop.Res.Univ.
(JAERI)(JAERI)
Coop.Res.Univ.Coop.Res.Univ.Coop.Res.Univ.Joint Res.
Coop.Res.Univ.(JAERI)
Coop.Res.Univ.Coop.Res.Univ.
Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.Joint Res.
Proj.Res.Univ.(JAERI)(JAERI)
(JAERI)(JAERI)
Coop.Res.Univ.
(JAERI)(JAERI)
Coop.Res.Univ.(JAERI)(JAERI)(JAERI)
Coop.Res.Univ.Coop.Res.Univ.Coop.Res.Univ.
(JAERI)(JAERI)(JAERI)
Coop.Res.Univ.
5.145.155.16c 17o. 11
6.16.26.36.46.5-66.76.8-96.106.116.126.136.146.156.16
6.176.186.19
7.1
7.2
7.37.47 R1 • 0
8.18.28.38.48.5
9.19.29.3-59.69.79.8-109.119.12
10.1-4
420294203242034
4201342014420154201842019420204202142022420234202542027420304204141022
/41023-4/42033
(off-line)(off-line)(off-line)
41028/41029
41033/41034
41034(off-line)(off-line)
4104441045410464104741048
4104141042—
420374203842039—
41040
—
Coop.Res.Univ.(JAERI)(JAERI)
PY* O I P o c I In i \zr 1 u j • rvco • ui 11 v •
(JAERI)Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.
(JAERI)(JAERI)(JAERI)(JAERI)
Proj.Res.Univ.Coop.Res.Univ.
(JAERI)Coop.Res.Univ./ (JAERI)/ (JAERI)
(JAERI)(JAERI)(JAERI)
(JAERI)/Coop.Res.Univ.
(JAERI)/Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.P*-/~* 1 R o c 11n 1 \irruj•nub•un x v*
Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.Proj.Res.Univ.
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Joint Res.
(JAERI)
* Joint Res. : Joint research with private company or governmental institutionCoop.Res.Univ. : Cooperative research with a university or universities #Proj.Res.Univ. : The JAERI-Universities Joint Research Project #
# For administration of these programs, we appreciate the cooperation of :Reasearch Center for Nuclear Science and Technology, The University of Tokyo.
- 263-
JAERI-Rcvicw 95-019
Appendix 3. Organization and personnel of TIARA (FY 1994)
1) Organization for the Research and Development of Advanced RadiationTechnology.
Presidentof
JAERI
Advanced ScienceResearch Center
Office ofPlanning
Tokai ResearchEstablishment
Naka FusionResearch
Establishment
Takasaki RadiationChemistry Research
Establishment
Consultative Committeefor the JAERI-Universities
Joint Research ProjectProf. M. Ishihara
Subcommittee forthe Advanced Radiation
Technology ProjectProf. K. Ishigure
TIARA General ProgramCommittee
Prof. S. Namba
Program AdvisoryCommittee
Dr. W. Kawakami
Osaka Laboratory forRadiation Chemistry
Department ofAdministrative Services
Department ofMaterial Development
Department ofRadiation Research for
Environment and Resources
Advanced RadiationTechnology Center
Consultative Committeefor the R & D of Advanced
Radiation TechnologyProf. K. Ishigure
Subcommittees for:
Accelerator FacilitiesDr. H. Kamitsubo
Radiation ResistantMaterials
Prof. A. Ushirokawa
BiotechnologyProf. H. Yamaguchi
Functional MaterialsProf. S. Namba
Positron Factory ProjectProf. M. Doyama
- 2 6 4 -
JAERI-Rcview 95-019
2) Personnel for the Administration, Operation and Control of TIARA*
Advanced Radiation Technology Center
DirectorDeputy Director
Administration DivisionGeneral ManagerStaff Member
Utilization and Coordination Divisioi
General ManagerStaff Member
Ion Accelerator Operation Division
General ManagerStaff Member
— Group of Cyclotron Operation
Staff Member
I. IshigakiR. Tanaka
E. YamasitaT. Suzuki, H. Tonooka
1
H. WatanabeS. Tanaka, K. Nishimura, M. Hosono
T. SasugaH. Tachibana
K. Arakawa, Y. Nakamura, T. NaraT. Agematsu, I. Ishibori
Group of Electrostatic Accelerators OperationStaff Member
Beam Engineering Division
General ManagerStaff Member
Department of Administrative Services
Safety Division
Staff Member(Radiation Monitoring and
Utilities and Maintenance Division
S. Tajima, I. Takada, K. MizuhashiS. Uno, K. Okoshi, Y. Nakajima
(R. Tanaka)W. Yokota, M. Fukuda, T. KamiyaS. Okumura, Y. Saitoh, Y. Ishi, T. Suda
T. Furuta, T. SakaiControl in TIARA)
Staff Member J. Yoshii, K. Fukuda(Radioactive Waste Management and Utility Control in TIARA)
• in FY 1994; For farther information, contact t o :Advanced Radiation Technology Center, Takasaki Radiation Chemistry ResearchEstablishment, Japan Atomic Energy Research Institute,1233 Watanuki-machi, Takasaki, Gunma-ken, 370-12, Japan.Telephone : (81)273-46-9600-3 ; Facsimile : (81)273-46-9690
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