Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
Track Core Size of Track Core Size of Proton and Heavy Ions Proton and Heavy Ions
inin PADC Detectors PADC Detectors
Tomoya YamauchiTomoya YamauchiKobe University, JapanKobe University, Japan
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Tomoya YAMAUCHI, Yutaka MORI, Keiji ODA,Tomoya YAMAUCHI, Yutaka MORI, Keiji ODA, Kobe University, Graduate School of Maritime
Sciences, 5-1-1 Fukaeminami-machi, Kobe, Japan.
Nakahiro YASUDA,Nakahiro YASUDA, National Institute of Radiological Science,
4-9-5 Anagawa, Inage-ku, Chiba, Japan.
RRéémi BARILLON,mi BARILLON,Institut Pluridisciplinaire Hubert Curien, 2
3 rue du Loess, Strasbourg, France.アンスティチュート・プリュリィディシプリネール・ユベール・キュイア
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
OrganizationOrganization
Outline of the present studyOutline of the present study
• Motivation & Purpose• Tracks in PADC
•UV-method: UV-visible absorption spectra, Track overlapping model (core size)(core size)•AFM-Method: Surface observation by Atomic Force Microscope after short-time etching (core size)(core size)•IR-method: Fourier transform-IR absorption spectra, G value (chemical modification)(chemical modification)
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
• Summary
Motivation & PurposeMotivation & Purpose
•For the development of new SSNTDs:
with higher sensitivity: 5 keV/µm >>> 0.5 keV/µm,
with controllable detection thresholds.
• To elucidate the track structure and track formation process in PADC and other polymers
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
MaterialsMaterials
• PADC: poly(allyl diglycol carbonate) BRYOTRAK (Fukuvi Chemical Industry) / CR-39
• PC: Bisphenol A polycarbonate
Macrofol KG (Good fellow)
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
In some physical models, track core is treated as the region where the primary or direct ionization is dominant,surrounded by the track halo or penumbra,that is produced by the secondary electrons or delta-rays.
In this work,……
What is track core?What is track core?
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
Track core size by three different ways:
1) UV-method1) UV-method: optically modified region due to the creation of some types of damage
2) AFM-method2) AFM-method: region where the local etching rate is significantly enhanced
3) IR-method3) IR-method: region where carbonate ester bonds and ether bonds are lost
What is track core?What is track core?
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
UV-Visible absorption spectra of UV-Visible absorption spectra of PADCPADC
Fig. 1 UV-Visible spectra of a PADC sheet and the
monomer.
Fig. 2 UV-Visible-Near IR spectra of a PADC sheet.
0
0.2
0.4
0.6
0.8
1
500 1000 1500 2000 2500 3000
Abs
orba
nce
Wavelength (nm)
C=O1st overtone
-OH, H2O
2751 nm: 3635 cm-1 : H2O anti-symmetric 2820 nm: 3550 cm-1 : OH, H2O symmetric 2880 nm: 3470 cm-1 : C=O the first overtone
0
1
2
3
4
5
200 250 300 350 400 450
unirrad.monomer
Opt
ical
Den
sity
Wavelength (nm)
C=O carbonyl
*
n *
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
UV-methodUV-method
Irradiations were carried out using a tandem Van de Graaff accelerator at Graduate School of Maritime Sciences, Kobe Univers
ity.
Table 1. Irradiation condition.Ion
speciesIncident energy
H+ 3.4 MeV KUMS
He2+ 5.1 MeV KUMS
C4+ 8.5 MeV KUMS
O4+ 7.0 MeV KUMS
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
UV-methodUV-method
UV-Visible spectra of PADC UV-Visible spectra of PADC sheets exposed to energetic sheets exposed to energetic
protons in vacuumprotons in vacuum
Fig. 3 UV-Visible spectra of PADC sheets exposed to 3.4 MeV
proton beams.
Fig. 4 UV-Visible spectra of PADC sheets exposed to 3.4 MeV proton beams at higher fluence
s.
The first peak is at 240 nm and the second one is at 280 nm.
0
0.5
1
1.5
2
2.5
3
200 250 300 350 400 450
1e125e121e132e132.5e134e138e13
Op
tica
l den
sity
Wavelength (nm)
ab
c
d
e
f
g
a
b
c
d
e
gf
fluence; ions/cm2
1st
2nd
0
1
2
3
4
5
200 250 300 350 400 450
8e131e144e146e147e14
Opt
ical
den
sity
Wavelength (nm)
gh
ijk
hg
i
k
j
Fluence; ions/cm21st
2nd
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
UV-methodUV-method
Dependence of the peak height and peak Dependence of the peak height and peak height ratio on proton fluence: 280nm/2height ratio on proton fluence: 280nm/2
40nm40nm
Fig. 5 Changes in the absorbance at the first and the second
peaks with proton fluence.
Fig. 6 Changes in the peak height ratio with proton fluence.
The height of 1st peak decreased around 2.5x1013 ions/cm2 .
The proportionality was lost at 1.0x1013 ions/cm2 .
0
0.5
1
1.5
2
2.5
3
3.5
4
1012
1013
1014
1015
Abs
orba
nce
at p
eaks
Fluence (ions/cm2)
O.D. = const x Fluence
1st peak (240nm)
2nd peak (280nm)0
0.5
1
1.5
1012
1013
1014
1015
Pea
k he
ight
rat
io (
280n
m) / (2
40nm
)
Fluence (ions/cm2)
3.4 MeV proton
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
UV-methodUV-method
Track overlapping and UV Track overlapping and UV absorption spectraabsorption spectra
0
1
2
3
4
200 250 300 350
Ab
sorb
an
ce
Wavelength (nm)
0
1
2
3
4
200 250 300 350
Ab
sorb
an
ce
Wavelength (nm)
Fig. 7 Without track overlapping, the optical density should be simply doubled when the fluence is doubled. Tracks are assumed to be simpl
e cylinders.
0
1
2
3
4
200 250 300 350
Ab
sorb
an
ce
Wavelength (nm)
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
UV-methodUV-method
Track piling (random number):Track piling (random number):track radius = 3.5 nmtrack radius = 3.5 nm
Fig. 8 Evolution of track piling with fluence (simulation).
1x 1011 ions/cm2
20 n
m/d
iv.
5 x 1011 ions/cm220
nm
/div
.1 x 1012 ions/cm2
20 n
m/d
iv.
5 x 1012 ions/cm2
20 n
m/d
iv.
1 x 1013 ions/cm2
20 n
m/d
iv.
100 nm
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
UV-methodUV-method
Pileup of Pileup of tracks (model)tracks (model)
Fig. 9 Evolution of track overlapping at various track radi
i.
Drops of
rain
Les feuilles morte
s0
0.2
0.4
0.6
0.8
1
108
109
1010
1011
1012
1013
1014
1015
1016
r = 0.2 nmr = 0.5 nmr = 1 nmr = 2 nmr = 3 nmr = 4 nmr = 5 nm
Occ
up
ied
fra
ctio
n: A
(n)
Fluence (ions/cm2)
( radius of latent track )
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
UV-methodUV-method
Critical fluence where the overlapping Critical fluence where the overlapping becomes significantbecomes significant
Fig. 11 Relation between the critical fluence and track radi
us.
0.1
1
10
1011
1012
1013
1014
Lat
ent
trac
k r
adiu
s (n
m)
Critical fluence (ions/cm2)
C He HO
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
0
0.2
0.4
0.6
0.8
1
1010
1011
1012
1013
1014
1015
1016
Occ
upie
d fr
acti
on
Fluence (ions/cm2)
Simple summation(proprotional to fluence)
Occupied area: A(n)
Single: A1(n)
Double: A2(n)
Triple: A3(n)
10 fold: A10
(n)
50 fold: A50
(n)
Track radius: rt = 1 nm
Fig. 10 Evolution of track overlapping with fluence.
UV-methodUV-method
Track core radius versus Track core radius versus stopping powerstopping power
Fig. 12 Relation between the track core radii and stopping p
ower from the UV method .
0
0.5
1
1.5
2
2.5
3
3.5
0 200 400 600 800 1000 1200 1400 1600
Lat
ent
trac
k ra
dius
(nm
)
Stopping power (keV/µm)
: rt = 0.048(dE/dx)0.55
by Apel et al. (1999)
: rt = 0.159(dE/dx)0.39
H
He
C
O
NIM B 208 (2003)149-154.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
UV-methodUV-method
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
HIMAC for heavier ionsHIMAC for heavier ionsHeavy Ion Medical Accelerator in ChibaHeavy Ion Medical Accelerator in Chiba
Table 2.
Ion species
Incident energy
O 8.6 MeV HIMAC
Ne 18.8 MeV HIMAC
Si 27.0 MeV HIMAC
Ar 35.0 MeV HIMAC
Fe 80.0 MeV HIMAC
Port Plaza ChibaHIMAC 共同利用研究成果発表会
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
UV-methodUV-method
Fig. 13 Relation between the track core radii and stopping power from the
UV method (HIMAC).
Track core radius versus Track core radius versus stopping powerstopping power
NIM B 236 (2005)318-322.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
UV-methodUV-method
0
1
2
3
4
5
6
7
0 1000 2000 3000 4000 5000
Tra
ck r
adiu
s (n
m)
Stopping power (keV/µm)
ONe
Si Ar
Fe
: rt=0.214(dE/dx)
0.38
Track core radius by UV-methodTrack core radius by UV-method
Fig. 14 Relation between the track core radii and stopping p
ower from the UV method.
0
1
2
3
4
5
6
0 1000 2000 3000 4000 5000
Track core radius in PADCby UV-method
Stopping power (keV/µm)
Track
core
radiu
s (n
m)
H
He
C
O
O
NeArSi
Fe
rt 0.159dE
dxkeV /m
0.39
nm ,
rt 0.214dE
dxkeV /m
0.38
nm ,
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
UV-methodUV-method
Track core radius ofTrack core radius offission fragments by fission fragments by
AFMAFM
Fig. 16 Evolution of minute etch pit of fission
fragments in the subsurface layer. The intersection on the coordinate indicates the core radius of fission fragments of about 6 nm.
0
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60 70
FF
y = 6.02 + 1.0717x R= 0.99494
Pit
rad
ius
(nm
)
Etching time (sec)
RM 37 (2003)119-125.
Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
Fig. 15 Typical AFM images of etched PADC. The samples were
etched in 6 M KOH solution at 70 ºC for 2 min (a) and 50 s (b).
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
AFM-methodAFM-method
HIMAC and HIMAC and VIVITRONVIVITRON
(Strasbour(Strasbour
g)g)
Ion
species
Incident energy
O 8.6 MeV HIMAC
Ne18.8 MeV
HIMAC
Si27.0 MeV
HIMAC
Ar35.0 MeV
HIMAC
Fe80.0 MeV
HIMAC
I200.0 MeV
VIVITRON
Xe240.0 MeV
HIMAC
Au250.0 MeV
VIVITRON
Table 3.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
AFM-methodAFM-method
Track core radius by AFM-methodTrack core radius by AFM-method
Fig. 17 Etch pits of Fe ion.Etching time: 60 s.
Fig. 18 Evolution of minute etch pit of heavy ions.
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70
ONeSiArFeIXeAu
Pit
rad
ius
[nm
]
Etching Time [sec]
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
AFM-methodAFM-method
Track core radius versus Track core radius versus stopping powerstopping power
Fig. 19 Relation between the track core radii and stopping power from the AFM and UV metho
ds.
0
5
10
15
20
0 5000 1 104 1.5 104 2 104
UV-methodONeSiAr
FeIXeAu
Tra
ck c
ore
rad
ius
(nm
)
Stopping power (keV/µm)
r = 0.214(dE/dx)0.38 Track core radii from the AFM method are greater than those from the UV methods for relatively he
avier ions.
Rev FMS.KU 2 (2006)179-184.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
AFM-methodAFM-method
FT-IR spectra of PADCFT-IR spectra of PADC
Fig. 20 FT-IR spectra of PADC films with various
thickness.
Fig. 21 Changes in absorbance for some bands
of PADC with film thickness.
0
0.5
1
1.5
2
2.5
3
80012001600200024002800320036004000
100 1553
Ab
sorb
nac
e
Wavenumber (cm-1
)
100 (m) 15 (m)
5 (m) 3 (m)
saturated
C-O-CC=O
0
0.5
1
1.5
2
2.5
3
0 10 20 30 40 50 60 70
Ab
sorb
ance
Thickness (m)
790 (cm-1
)
880 (cm-1
)
2955 (cm-1
)
Beer-Lambert
law
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear
Tracks in Solid
IR-methodIR-method
Loss of carbonyl along tracks in Loss of carbonyl along tracks in PADCPADC
Fig. 22 Spectral change of PADC in IR region by Fe ion irrad
iation.
Fig. 23 Decrease of carbonate ester bonds with heavy ion flu
ence.
0.6
0.7
0.8
0.9
1.0
1.1
0 1 1012 2 1012 3 1012 4 1012 5 1012
C
Ne
Ar
Fe
Rel
ativ
e ab
sorb
ance
: A/A
0
Fluence (ions/cm2)
Carbonyl bond: 1770 cm-1
C=O
0.0
0.5
1.0
1.5
2.0
100012001400160018002000
UnirradiatedIrradiated
Abs
orba
nce
Wavenumber (cm -1)
Fe 147 MeV 1.5x1011
ions/cm2
carbonateester
C-O-C
CH2
CH2
carbonate ester
C=O
ether
C-O-C
N F N0
1 F,
A F A0
N F
N0
,
L N0 .
rt2,
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
IR-methodIR-method
Fig. 24 Relation between the track core radii and stopping power from the IR-method (GANIL
&HIMAC).
0
1
2
3
4
5
6
7
8
0 1000 2000 3000 4000 5000 6000 7000
UV
IR
Tra
ck c
ore
rad
ius
(nm
)
Averaged LET (keV/m)
Cether
Fe: present work
O Ne
Si Ar
Fe
carbonate ester
ether
0
1
2
3
4
5
6
0 1000 2000 3000 4000 5000 6000
Eff
ecti
ve t
rack
cor
e ra
diu
s (n
m)
Stopping power (keV/µm)
UV-method
Fe
Ar
Ne
C
Fig. 25 Relation between the track core radii and stopping power from the IR-method (HIMA
C).
Track core radius Track core radius by IR-methodby IR-method
JJAP 47 (2008)3606-3609.
RM 40 (2005)224-228.RM 43 (2008)S106-S110.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
IR-methodIR-method
Track core radius by UV, AFM and Track core radius by UV, AFM and IR methodsIR methods
Fig. 26 Relation between the track core radii and stopping power from the three methods.
0
5
10
15
20
0 5000 1 104 1.5 104 2 104
Track core radius in PADC
Stopping power (keV/µm)
Track
core
radiu
s (n
m)
UV-methodKobe Univ.
UV-methodHIMAC
IR-method
AFM-method
AFM-method
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
discussiondiscussion
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
Track core radius by UV, AFM and IR methods
Fig. 27 Relation between the track core radii and stopping power from the three methods.
0.1
1
10
100 1000 104
Track core radius in PADC
Track
core
rad
ius
(nm
)
Stopping power (keV/µm)
UV-methodKobe Univ.
UV-methodHIMAC
IR-method
AFM-method
AFM-method
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
discussiondiscussion
Track core radius and G value (1/3)
Experimentally obtained relation:
N F N0
1 F .
Where F is fluence. At a fluence of 1 ion/cm2,
N 1 N0 N0,
N0 N0 N 1 .This indicates the number of decreased bond per unit length of one track, i.e.
damage density, L:
L N0 .
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
discussiondiscussion
Track core radius and G value (2/3)
G value is attained by dividing L by the average stopping power in films, .
G N0
S .
If the track core radius is proportional to the square root of stopping power,
rt aS 0.5,
rt2 a2S ,
G value was independent of the stopping power, as:
G N0
S
a2S
S a2 .
S
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
discussiondiscussion
Track core radius and G value (3/3)
Fig. 28 Relation between the track core radii and stopping p
ower.
0
2
4
6
8
10
12
14
0 5000 1 104 1.5 104 2 104
EFG
G v
alu
e (
/10
0 e
V)
Stopping power (keV/µm)
Fig. 29 Relation between G value and stopping power.
0
2
4
6
8
10
0 5000 1 104 1.5 104 2 104
BCD
Track
core
rad
ius
(nm
)
Stopping power (keV/µm)
rt aS 0.5
rt aS 0.5
rt aS 0.62
rt aS 0.62
rt aS 0.38
rt aS 0.38
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
discussiondiscussion
Tracks in PADC
Fig. 30 Relation between the track core radii and stopping p
ower in PADC.
0.0
2.0
4.0
6.0
8.0
10.0
0 2000 4000 6000 8000 10000 12000 14000
y = 0.034672 * x^(0.57099) R= 0.9938
y = 0.11691 * x^(0.3833) R= 0.98088
Tra
ck c
ore
rad
ius
(nm
)
Stopping power (keV/µm)
He
C
Ne
Ar
Fe
Xe
rt 0.214dE
dxkeV /m
0.38
nm ,
rt 0.159dE
dxkeV /m
0.39
nm .
by UV method
rt aS 0.57
rt aS 0.38
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
discussiondiscussion
Tracks in PADC
Fig. 30 Relation between the track core radii and stopping p
ower in PADC.
0
2
4
6
8
10
12
0 2000 4000 6000 8000 10000 12000 14000
G v
alu
e (b
ond de
st/1
00 e
V)
Stopping power (keV/m)
He
C
Ne
Ar Fe Xe
Fig. 31 Relation between the G value for loss of C=O and stop
ping power in PADC (1).
0.0
2.0
4.0
6.0
8.0
10.0
0 2000 4000 6000 8000 10000 12000 14000
y = 0.034672 * x^(0.57099) R= 0.9938
y = 0.11691 * x^(0.3833) R= 0.98088
Tra
ck c
ore
rad
ius
(nm
)
Stopping power (keV/µm)
He
C
Ne
Ar
Fe
Xe
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
discussiondiscussion
Tracks in PADC
Fig. 32 Relation between the G value for loss of C=O and stop
ping power in PADC (2).
2
4
6
8
10
12
0 2000 4000 6000 8000 10000 12000 14000
G v
alue
(bo
ndd
est/1
00eV
)
Stoping power (keV/µm)
He
C
Ne
Ar Fe Xe
rCO 0.0347dE
dxkeV /m
0.57
nm .
rCO 0.117dE
dxkeV /m
0.38
nm .
0.0
2.0
4.0
6.0
8.0
10.0
0 2000 4000 6000 8000 10000 12000 14000
y = 0.034672 * x^(0.57099) R= 0.9938
y = 0.11691 * x^(0.3833) R= 0.98088
Tra
ck c
ore
rad
ius
(nm
)
Stopping power (keV/µm)
He
C
Ne
Ar
Fe
Xe
Fig. 30 Relation between the track core radii and stopping p
ower in PADC.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
G value = 17 (/100eV) for gamma-ray !!
discussiondiscussion
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
Summary 1/2Summary 1/2
Higher G values at lower stopping power in PADC not
in PC
Summary 2/2Summary 2/2
Good selections of the molecule structure between two carbonate ester bonds
can provide us sufficient polymers for SSNTDs.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
Thank you for your attention!
Grazie!
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
Bologna, 200824th Int. Conf. Nuclear Tracks in S
olid
G valueG value: ICRU report 60, 1998: ICRU report 60, 1998 Fundamental Quantities and Units for Ionizing Radiation
• The radiation chemical yield, G(x), of an entity, x, is the quotient of n(x) by , where n(x) is the mean amount of substance of that entity produced, destroyed, or changed in a system by the energy imparted, , to the matter of that system, thus,
Unit: mol J-1
G x n x
.
The related quantity, called G value, has been defined as the number of entities produced, destroyed or changed by an energy imparted of 100 eV. The unit in which the G value is expressed is (100 eV)-1. A G value of 1 (100 eV)-1 corresponds to a radiation chemical yield of 0.104 µmol J-1.
ICRU: International Commission on Radiation Units ICRU: International Commission on Radiation Units and Measurementsand Measurements
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
Occupied area by tracks: A(n)Occupied area by tracks: A(n)at fluence of n (ions/cmat fluence of n (ions/cm22), track area o), track area o
f sf s
Fig. 10 Fraction of the occupied area by tracks.
Probability
A(n-1) fall into the occupied area
1-A(n-1)fall into the non-occupied area
A(n) A(n 1) s 1 A n ,A n 1 1 s n
.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
N-folds area by tracks: AN-folds area by tracks: ANN(n)(n)
A n 1 1 s n,
A n 1 exp sn A1 n A2 n A3 n AN n
A1 n sn exp sn ,
A2 n sn 2
2
exp sn ,
A3 n sn 3
6
exp sn ,
AN n sn N
N!
exp sn ,
Fig. 11 Evolution of track overlapping
with fluence.Poisson
distribution
0
0.2
0.4
0.6
0.8
1
1010
1011
1012
1013
1014
1015
1016
Occ
upie
d fr
acti
on
Fluence (ions/cm2)
Simple summation(proprotional to fluence)
Occupied area: A(n)
Single: A1(n)
Double: A2(n)
Triple: A3(n)
10 fold: A10
(n)
50 fold: A50
(n)
Track radius: rt = 1 nm
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
Determination of the critical fluences Determination of the critical fluences for He and Cfor He and C
Fig. 13 Changes in the absorbance at the first and the second peaks with helium ion fluenc
e.
Fig. 14 Changes in the absorbance at the first and the second peaks with carbon ion fluenc
e.
0
0.5
1
1.5
2
2.5
1011
1012
1013
1014
Abs
orba
nce
at p
eaks
Fluence (ions/cm2)
1st peak (240nm)
2nd peak (240nm)
O.D. = constant x fluence
He
0
0.5
1
1.5
2
2.5
3
1011
1012
1013
1014
Abs
orba
nce
at p
eaks
Fluence (ion/cm2)
C
O.D. = constant x Fluence
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
Determination of the critical fluencesDetermination of the critical fluences
Fig. 15 Changes in the absorbance at the first and the second peaks with oxygen ion fluenc
e.
Fig. 16 Changes in the peak height ratio with ion fluence.
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1011
1012
1013
1014
Pea
k he
ight
rat
io (2
80nm
) / (240
nm)
Fluence (ions/cm2)
O
C
He
H
0
0.2
0.4
0.6
0.8
1
1011
1012
1013
1014
O
Abs
orba
nce
at p
eaks
Fluence (ions/cm2)
O.D. = constant x fluence
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
AFM-method AFM-method without etchingwithout etching
Tracks of 80 MeVAu ion in PMMA
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
AFM-methodAFM-methodOLYMPUS NanoVision 2000
0
200
400
600
800
1000
1200
0 500 1000 1500 2000
FFAlpha
Pit
rad
ius
(nm
)
Etching time (sec)
Vb = 2.5 µm/h
optical microscope
Fig. 21 Etch pit radii for fission fragments and alpha-particles as a function of the etch
ing time.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
RM 37 (2003)119-125.
0
2
4
6
8
10
0 5000 1 104 1.5 104 2 104 2.5 104
Lat
ent
trac
k r
adiu
s (n
m)
Stopping power (keV/µm)
rt = 0.048(dE/dx)0.55
by Apel (1999)
: rt = 0.159(dE/dx)0.39
F.F. by AFM
HHe
C
O
Fig. 23 Assessed latent track radial size in PADC plastics for light ions and fission fragment indicating as a function
of stopping power.
Track core Track core radius by IR-radius by IR-
methodmethod
Fig. 31 Relation between the track core radii and stopping power from the IR-method (GANIL
&HIMAC).
0
1
2
3
4
5
6
7
8
0 1000 2000 3000 4000 5000 6000 7000
UV
IR
Tra
ck c
ore
rad
ius
(nm
)
Averaged LET (keV/m)
Cether
Fe: present work
O Ne
Si Ar
Fe
carbonate ester
ether
GANIL: Grand Accelerateur National d’Ions Lourds
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
Track core radius in PC
0.1
1
10
100
0 5000 10000 15000 20000
Tra
ck c
ore
rad
ius
(nm
)
Stopping power (keV/m)
NiAu UF
O
AuXeAlkyne Amorphization
present work
AmorphizationAlkyne
rCO 0.0378dE
dxkeV /m
0.55
nm .
Fig. 33 Relation between the track core radii and stopping power in PC from various method
s.Rev FMS.KU 4 (2006)61-70.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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Tracks in PC
0
1
2
3
4
5
6
7
0 2000 4000 6000 8000 10000 12000
y = 0.040687 * x^(0.53848) R= 0.99783
Eff
ecti
ve t
rack
cor
e ra
diu
s (n
m)
Stopping power (keV/m)
He
C
Ne
Ar
FeFe
fitting curve
0
1
2
3
4
5
0 2000 4000 6000 8000 10000 12000
G v
alu
e (C
=O
dest/1
00eV
)
Stopping power (keV/m)
He
NeCAr Fe
Fe
Fig. 34 Relation between the track core radii and stopping p
ower in PC.
Fig. 35 Relation between the G value for loss of C=O and stop
ping power in PC.
Almost independent of stopping power
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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Tracks in PADC
Fig. 41 Radial dose distribution of energy deposited around
the path of heavy ions in PC. Fig. 42 Radial dose distribution of energy deposited around the path of heavy ions in PAD
C.
104
105
106
107
108
109
0.1 1 10
Loc
al d
ose
(Gy)
Distance from the ion's path (nm)
CNe
ArFe
Xe
PC
104
105
106
107
108
109
0.1 1 10
Loc
al d
ose
(Gy)
Distance from the ion's path (nm)
CNe
Ar Fe
proton 1 MeV
Effective track core radius of C ion
PADC
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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Gamma-irradiated PADC
Fig. 41 Decrease of the relati
ve absorbance with gamma-dose. Fig. 42 G value for loss of carbonate ester bonds in gamma and heavy ion irradiated PADC.
24th International Conference on Nuclear Tracks in Solids 1 - 5 September 2008, Bologna
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olid
0.6
0.7
0.8
0.9
1
1.1
0 200 400 600 800 1000 1200
C=OC-O-C
Rel
ativ
e ab
sorb
ance
: A/A
0
Absorsed dose (kGy)
0
5
10
15
20
0 2000 4000 6000 8000 10000 12000 14000
G v
alue
(bo
ndd
est/1
00 e
V)
Stopping pawer (keV/m)
C Ne
FeXe
Ar
He
Gamma-ray
• A review was given for the present status of our study on track core radii for proton and heavy ions in PADC.
• Evaluated core radii were dependent on the methods: UV, AFM, and IR-methods.
rUV rIR rAFM
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Summary 1/3Summary 1/3