Progress on Transmutation Experiments
induced by D2 gas permeation
T.Itoh1,2, J. Kasagi1, Y.Iwamura1, S.Tsuruga3
1Condensed Matter Nuclear Reaction Division, Research Center for Electron
Photon Science, Tohoku University, Sendai 982-0826, Japan 2CLEAN PLANET Inc., Tokyo 105-0022, Japan 3 Research & Innovation Center, Mitsubishi Heavy Industries, Ltd., Yokohama 236-8515, Japan
12th International Workshop on Anomalies in Hydrogen Loaded Metals
1
Cs → Pr Transmutation MHI Experiments
Pr141
59
133
55Cs
J. J. App. Phys. 41(2002)4642 2
Replicated experiment of Toyota lab
D2 permeation
No
Cs, o
nly
Mu
ltila
ye
r
No
Cs, N
o M
ultila
ye
r
Cs implanted
Multilayer
Hioki et al. JJAP 52 (2013) 107301 3
There is a criticism that the mass of the nucleus was not
identified, since the employed mass spectrometry, such as ICP-
MS, cannot exclude possibilities of chemical compound objects.
Direct assignment of the nucleus (141Pr) by using nuclear
physics approach is highly demanded.
Successive various measurements showed existencs of 141Pr
XPS, ICP-MS, Tof-SIMS, In-situ XRF at SPring8
Object
Therefore, we employed the Rutherford Backscattering
Spectroscopy (RBS) to identify 141Pr for direct nuclear mass
assignment. 4
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
650 850 1050 1250 1450
7007+7008
X
dY ∝ ρTNb(ds/dW)(x) dx
= ρTNb(ds/dW)(E) (dE/dx)-1dE
dY1/dE
dY2/dE
dY1/dY2 ~ (ρ1/ρ2) (Z1/Z2)2
Distributed near surface
Scattered by Nucleus; Mass determined by kinematics
Advantage for large A and Z
Pd density:6.8×1022 atoms/cm3
(ZPd/ZW)2 = (46/74)2 = 0.386
W is more sensitive than Pd by 2.6 times
W density:~5.4×1020 atoms/cm3
Example: Compare W on surface / Pd
Rutherford Backward Scattering(RBS)
x
Pd base Surface Elements
40Ar, 128MeV
5
Expected RBS Spectrum by irradiation 128-MeV 40Ar
102
103
104
10
1
105
106
0 10 20 30 40 50 60 Energy (MeV)
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(1) Pt impurity in thick Pd :100 ppm
(2)133Cs:uniformly distributed in 0 - 20 nm depth; 200ng/cm2
(3)141Pr: uniformly distributed in 0 - 10 nm depth; 60 ng/cm2 30 ng/cm2 15 ng/cm2
60 ng/cm2
30 ng/cm2
15 ng/cm2
6
Cs transmutation sample by D2 gas Permeation
D2
Sample for RBS was provided by MHI
900℃ 10H Annealing
under Vacuum Condition
Washing a Pd Sample
with Acetone
Washing the Sample with
Aqua Regia
Fabrication Pd-CaO
Multilayer using Ion Beam
Spattering
Cs Deposition
D2 Gas permeation
7
ECR ion source + 930 AVF Cyclotron
Large Scattering chamber
Cyclotron Radioisotpe Center, Tohoku University
8
Geometric Arrangement of Beam, Target and detector
40Ar7+ 128MeV
Target
Detector(Si) Beam: 40Ar7+ 128MeV ~ 1 particle nA Si detector: 300 m in thickness 300 mm2x3, 450 mm2x2
= 165° total = 0.083 sr
Several-hour measurement for a sample to identify Pr of 10 ng/cm2
9
Sensitivity of Pr identification
RBS spectrum Pr-implanted Pd/CaO foil
Implanted:23.4 ng/cm2
Measured:18.9±4.8 ng/cm2
Reproduced well !!
Pt BG: ~ 95 ppm of Pd
By measuring several hours,10 ng/cm2-Pr can be detected with
the confidence level of 99% (or statitical significance of 2.6σ).
Pr
*test peace was provided by Toyota Central Research and Development Laboratories 10
Sample Target
Am
ZnSe
Au
Au(10nm)/Si
Au
Pt
Pd
test peace
Pr Implantation 1014
Pr:23.4ng/cm2
Ref Sample
(Only Multilayer)
test peace
Cs Implantation
FG sample(SK137)
FG sample(SK132)
Ref Sample
(Cs Dope,
No D2 Permeation)
FG sample(SK130)
Cs:134ng/cm2
Pr:74ng/cm2
Cs: 94.6 ng/cm2
Pr: 51 ng/cm2
Cs: 57.7 ng/cm2
Pr: 50.8 ng/cm2
11
RBS spectrum:with D2 gas permeation Summed spectrum of foreground samples
0 10 20 30 40 50 60 Energy (MeV)
102
103
104
10
1
105
106
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Thick Pd
141Pr natW
A=192
W→Pt ??
~1/5000
100 ppm Pt
133Cs
BG: mainly Pt impurity in thick Pd ~100 ppm→BG determine a detection limit. 133Cs:distributed 0 - 80 nm in depth natW: distributed 0 - 80 nm in depth contamination of W(182,183,184,186) of multilayer
(1) A tiny peak at A=141 (141Pr)
141Pr exists on the surface. not observed for without D2 consistent with MHI
report
(2) Pt region: peak structure Pt impurity in Pd in surface layer? W → Pt ? 12
RBS spectrum:with D2 gas permeation Summed spectrum of foreground samples
0 10 20 30 40 50 60 Energy (MeV)
102
103
104
10
1
105
106
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Thick Pd
141Pr natW
A=192
W→Pt ??
~1/5000
100 ppm Pt
133Cs
BG: mainly Pt impurity in thick Pd ~100 ppm→BG determine a detection limit. 133Cs:distributed 0 - 80 nm in depth natW: distributed 0 - 80 nm in depth contamination of W(182,183,184,186) of multilayer
(1) A tiny peak at A=141 (141Pr)
141Pr exists on the surface. not observed for without D2 consistent with MHI
report
(2) Pt region: peak structure Pt impurity in Pd in surface layer? W → Pt ?
(1)
13
RBS spectrum with D2 gas permeation: Cs, Pr
detection
10-1
102
103
104
10
1
0 10 20 30 40 50 60
Energy (MeV)
Pd
Cs
Pr
Pt
Sample name:SK132
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0
10
20
30
40
30 32 34 36 38 40 42 44 46 48 50
Energy [MeV]
Pt(BG)
Sample Name:SK130
Exp.
Pt (BG)
fit
30 32 34 36 38 40 42 44 46 48 50
Cou
nt [
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t/2
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Energy [MeV]
0
10
20
30
40
Sample Name:SK132 Exp.
Pt (BG)
fit
Count
[count/100kev]
14
Pr amount comparison of ICP-MS and RBS
Sample Name Analytical method Cs(ng/cm2) Pr(ng/cm2)
SK130 ICP-MS 57.7 50.8
RBS 94.1±10.9 < 6
SK132 ICP-MS 94.6 51
RBS 37.8±5.9 < 5.1±2.6
SK137 ICP-MS 134 74
RBS 19.7±7.8 < 11
Pr test Sample Pr Implanted 23.4
RBS 19±5
Comparing between the results of ICP-Ms and RBS,
quantitative agreement is not good.
Y(RBS)/Y(ICP) = 0.15 ~ 1.63 for 133Cs
< 0.15 for 141Pr
→ Measurement points of ICP-MS and RBS are different?
→ may be due to the local distribution of 141Pr
15
Non-uniform distribution of Pr (XRF @ SPring-
8)
0
200
400
600
800
1000
1200
3.5 4 4.5 5 5.5
Energy(keV)
Counts
Point 4-4 (Much Pr detection)
Point 3-4(Pr detection)
Point 6-4(No Pr)
Cs
Pr4X1014/cm2
1X1014/cm2
0
200
400
600
800
1000
1200
3.5 4 4.5 5 5.5
Energy(keV)
Counts
Point 4-4 (Much Pr detection)
Point 3-4(Pr detection)
Point 6-4(No Pr)
Point 4-4 (Much Pr detection)
Point 3-4(Pr detection)
Point 6-4(No Pr)
Cs
Pr4X1014/cm2
1X1014/cm2
100 micron beam;SP-24, 13-4
6
5
4
3
2
1
654321
6
5
4
3
2
1
654321X
Y
100μ m
100μ m
Much Pr detection
Pr detection
No Pr
13-4
XRF study shows: Existing probability of Pr strongly depends on location
Average value of Pr in 13-4 4.4×1013 atoms/cm2
Y. Iwamura et al., Condensed Matter Nuclear Science, World Scientific, New Jersey, p.178, 2006. 16
RBS spectrum:with D2 gas permeation Summed spectrum of foreground samples
0 10 20 30 40 50 60 Energy (MeV)
102
103
104
10
1
105
106
Co
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t/1
00
ke
v]
Thick Pd
141Pr natW
A=192
W→Pt ??
~1/5000
100 ppm Pt
133Cs
BG: mainly Pt impurity in thick Pd ~100 ppm→BG determine a detection limit. 133Cs:distributed 0 - 80 nm in depth natW: distributed 0 - 80 nm in depth contamination of W(182,183,184,186) of multilayer
(1) A tiny peak at A=141 (141Pr)
141Pr exists on the surface. not observed for without D2 consistent with MHI
report
(2) Pt region: peak structure Pt impurity in Pd in surface layer? W → Pt ?
(2)
17
W & Pt in Pd-CaO Multilayer
Pd Substrate
Target (Pd,CaO)
Ar Ion (1kV15〜20mA)
W Filament ●Pd(multilayer&Substrate)
contain Pt about 100ppm ●Pd-CaO multiLayer contain
W from ion source
CaO(2nm)
CaO(2nm)
CaO(2nm)
CaO(2nm)
CaO(2nm)
Pd(40nm)
Pd(20nm)
Pd(20nm)
Pd(20nm)
Pd(20nm)
Pd
100μm
Ion beam Sputtering Apparatus
18
RBS spectrum:with D2 gas permeation Summed spectrum of foreground samples
0 10 20 30 40 50 60 Energy (MeV)
102
103
104
10
1
105
106
Co
un
t [co
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t/1
00
ke
v]
Thick Pd
141Pr natW
A=192
W→Pt ??
~1/5000
100 ppm Pt
133Cs
BG: mainly Pt impurity in thick Pd ~100 ppm→BG determine a detection limit. 133Cs:distributed 0 - 80 nm in depth natW: distributed 0 - 80 nm in depth contamination of W(182,183,184,186) of multilayer
(1) A tiny peak at A=141 (141Pr)
141Pr exists on the surface. not observed for without D2 consistent with MHI
report
(2) Pt region: peak structure Pt impurity in Pd in surface layer? W → Pt ? 19
RBS spectrum Pd multi-Layer without Cs dope & D2 permeation
Samle name: M115
0
200
400
600
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46 48 50 52 54 56 58 60
Energy [MeV]
Pd-CaOMultilayer
contamination from filament of ion source
20
0
20
40
60
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46 48 50 52 54 56 58 60
Energy [MeV]
Samle name: S55B
RBS spectrum Cs Doped multilayer without D2 permeation
Pd-CaO Multilayer Cs
Pt(impurity of Pd)
W
21
40
60
80
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46 48 50 52 54 56 58 60
Energy [MeV]
0
20
Pd-CaO Multilayer Cs
D2 Permeation
RBS spectrum
Cs Doped multilayer after D2 permeation
Samle name: SK130
Mass 〜192
W
Pt
22
200
300
400
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46 48 50 52 54 56 58 60
Energy [MeV]
0
100
Pd-CaOMultilayer Cs
D2 Permeation
RBS spectrum
Cs Doped multilayer after D2 permeation
Samle name: SK132
Mass 〜192
W
23
What is a peak A=192 Os? Ir?, Pt?
Samle name: SK130
40
Co
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co
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100ke
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46 48 50 52 54 56 58 60 Energy [MeV]
0
20 ?
W
50 51 52 53 54 55 56 57 58 59
40
0
20
10
30
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Pt (Natural)
Ir(Natural)
Os(Natural)
20
0
10
50 52 54 56 58
Ir(Natural)
W(Natural)+4d:Transmutation
Count [
count/
100kev]
Energy [MeV] Energy [MeV]
Sample W(ng/cm2) A~192 (ng/cm2)
SK130 346±14 91.7±7.4
Sk132 697±13 90.8±5.0
Sk137 911±20 104±7
Ir natural :191Ir (37%) 193Ir(63%) 24
Conclusion
1.We performed Rutherford Backscattering Spectroscopy
(RBS) to identify 141Pr for direct nuclear mass assignment.
2. For FG samples, we could identify the 141Pr events as well
as 133Cs, although the statistics is not enough. A comparison of
the results between ICP-Ms and RBS shows that a quantitative
agreement is not good.
Y(RBS)/Y(ICP) = 0.15 ~ 1.63 for 133Cs
< 0.15 for 141Pr
→ Measurement points of ICP-MS and RBS are
different?
→ may be due to the local distribution of 141Pr
3. A broad peak indicating the existence of a nuclide with mass
number around 192 was observed. There is a possibility that
the impurity W in Pd/CaO multi-layer complex was transmuted
into the elements of mass around 192. 25
Acknowledge
RBS measurement was partially supported by IMPACT
Program of Council for Science, Technology and Innovation in
2015. Program name is “Reduction and Resource Recycle of
High Level Radioactive Wastes with Nuclear Transmutation”.
The authors would like to thank
Mr. Ryo Tajima, Dr.Yuki Honda, and Prof. Hidetoshi Kikunaga
for their corporations on RBS analysis, Research Center for
Electron Photon Science, Tohoku University and
Mr. Hideki Yoshino and Mr. Masanao Hattori for their supports.
26
27
W+4d 183W(19%) + 4d → 191Pt (τ1/2 = 2.8 d)
28