Track etch based LET spectrometry
in beams of neutrons with energies
from 0.2 to 200 MeV
Brabcová Kateřina
Spurný František
Jadrníčková Iva
Department of Radiation Dosimetry, Nuclear
Physics Institute, Academy of Sciences of
the Czech Republic, Prague,
[email protected]
content
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briefly about neutron dosimetry
track etched detectors (TED)
conditions of our experiments
results
conclusion
about neutron dosimetry
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indirectly ionizing radiation, energy
transferred through the kinetic energy of
secondary charged particles
large spectrum of the secondary particles
created in detector or around
LET spectra should be known
experimental methods of LET
spectrometry
• tissue-equivalent proportional counters,
bubble detectors, nuclear emulsions,
• in case of long exposure, limitation in
weight and dimension, presence of intense
low LET radiation :
track etched
based LET
spectrometers
TED generally
• mostly polyallyldiglycolcarbonate C12H18O
• evaluation by etching
• measuring of track parameters
etch rate of damaged material
etch ratio
• calibration
VT
V
VB etch rate of unaffected material
LET  f (V )
our TED
• polyallyldiglycolcarbonate C12H18O
Page, 0.5 mm (Page Moulgings Ltd, England)
Tastrak, 0.5 mm (Track Analysis Systems Ltd, Bristol)
• evaluation by etching
5 M NaOH at 70oC for 18 hours
• measuring of track parameters
automatic optical image analyzer LUCIA G
• calibration
calibration of TED
• heavy charged particle beams
– 84Kr
LET from 7.5 to 600 keV/μm
12C
• performed in cooperation with
HIMAC (NIRS Chiba, Japan) in the frame of ICCHIBAN
programs – ICCHIBAN 2, 4, 6, and 8
NASA Space Radiation Laboratory (Brookhaven National
Laboratory) in the frame of ICCHIBAN BNL
Nuclotron of the Laboratory of High Energies, JINR,
Dubna
experiment EC-JRC
• done at the Van de Graaff facility at the
EC-JRC, Geel
• quasi mono-energetic neutron beams
produced by protons and deuterons
• 7 different energies of neutron beams
from 200 keV to 20 MeV
• reference values – neutron fluences and
neutron spectra, ambient dose equivalent
H*(10)
experiment iThemba
• done in iThemba laboratory, Cape Town
• quasi mono-energetic neutron beams
produced by deuterons and Li targets
• 2 energies of neutron beams – 100 and
200 MeV
• reference values – neutron fluences and
neutron spectra, ambient dose equivalent
H*(10)
experiment EC-JRC
Page - LET distribution of H
0.30
0.25
?
LET*H
0.20
0.2 MeV
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
Page - LET distribution of H
0.30
recoil protons up to
100 keV.μm-1
0.25
LET*H
0.20
0.2 MeV
0.5 MeV
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
Page - LET distribution of H
0.30
0.25
LET*H
0.20
0.2 MeV
0.5 MeV
1 MeV
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
Page - LET distribution of H
0.30
0.25
LET*H
0.20
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
Page - LET distribution of H
0.30
(n,x)X
0.25
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
7 MeV
LET*H
0.20
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
Page - LET distribution of H
0.30
0.25
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
7 MeV
16 MeV
LET*H
0.20
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
Page - LET distribution of H
0.30
0.25
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
7 MeV
16 MeV
20 MeV
LET*H
0.20
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
0.5 mm Tastrak - LET distribution of H
0.25
LET*H
0.20
0.15
0.2 MeV
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
0.5 mm Tastrak - LET distribution of H
0.25
LET*H
0.20
recoil protons up to
100 keV.μm-1
0.15
0.2 MeV
0.5 MeV
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
0.5 mm Tastrak - LET distribution of H
0.25
LET*H
0.20
0.15
0.2 MeV
0.5 MeV
1 MeV
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
0.5 mm Tastrak - LET distribution of H
0.25
LET*H
0.20
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
0.5 mm Tastrak - LET distribution of H
0.25
(n,x)X
LET*H
0.20
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
7 MeV
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
0.5 mm Tastrak - LET distribution of H
0.25
LET*H
0.20
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
7 MeV
16 MeV
0.15
0.10
0.05
0.00
10
100
1000
-1
LET [keV.μm ]
experiment EC-JRC
0.5 mm Tastrak - LET distribution of H
0.25
LET*H
0.20
0.2 MeV
0.5 MeV
1 MeV
3.5 MeV
7 MeV
16 MeV
20 MeV
0.15
0.10
0.05
0.00
10
100
LET [keV.μm -1]
1000
experiment iThemba
100 MeV
0.2
Page
0.5 mm Tastrak
0.18
0.16
LET*H
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
10
100
1000
-1
LET [keV.μm ]
experiment iThemba
100 MeV and 200 MeV
0,2
Page 100 meV
Tastrak 100 MeV
Page 200 MeV
Tastrak 200 MeV
0,18
0,16
LET*H
0,14
0,12
0,1
0,08
0,06
0,04
0,02
0
10
100
LET [keV.μm -1]
1000
dosimetric characteristic
HLET = ∫ (dN / dLET) . LET . Q(LET) . dLET
dose equivalent due to registered particles
dN/dLET – number of tracks N in a LET interval dLET
Q(LET) – ICRP 60 quality factor
H*(10)
ambient dose equivalent (reference value)
response of detectors
ratio HLET/H*(10)
10
Page
T0,5
1
0.1
0.1
1
10
neutron energy in MeV
100
1000
conclusion
• TED provides new information about neutron
energy transfer to the matter
• dose equivalent of secondary particles is lower
than ambient dose equivalent H*(10)
• intention of futher studies
experiment with another neutron energies
deal with unexpected values of 200 keV and 7 MeV
Acknowledgements
• Part of study has been realised in the frame of
ESA DOBIES project. We are obliged to Filip
Vanhavere (SCK MOL, Belgium) for the
coordination of the project, and to ESA Prodex
Office for financial assistance.
• Many of results presented in this contribution
were obtained by using the results of ICCHIBAN
research project using heavy Ions at HIMACNIRS, NSRL–BNL, nuclotron JINR Dubna. We
are much obliged to the staff of all laboratories
and, particularly, to organizers of the run, Y.
Uchihori, N. Yasuda, J. Miller, E.R. Benton, A.G.
Molokanov, and V.P. Bamblevski† for their help.
• Studies were also partially supported through
the grant No. 202/04/0795 of the GA CR and the
IRP AV0Z10480505.
Thank you!