Neutron Spectrometry with H e -3 proportional counters
description
Transcript of Neutron Spectrometry with H e -3 proportional counters
NEUTRON SPECTROMETRY WITH He-3 PROPORTIONAL
COUNTERSM. Manolopoulou1, M. Fragopoulou1, S. Stoulos1, E.
Vagena1, W. Westmeier2, M. Zamani1
1School of Physics, Aristotle University of Thessaloniki, Hellas
2Philipps-Universität, 35032 Marburg, Germany
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Outline Operational characteristics of the counter Energy Calibration Efficiency Calibration Simulation with Geant4 and comparison
with the experimental results Neutron spectrum unfolding example
2
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0 1000 2000 3000 4000 5000 6000 7000100
1000
10000
100000
Deposited energy [MeV]
Coun
ts
0.68 MeV
0.89 MeV
1.1 MeV
3.3 MeV
5.0 MeV
5.6 MeV
He-3 counter spectra
Full energy peak
3He(n,p)3HQ=764 keV
Recoil peak 3He(n,elastic)
0.75*En
3He(n,d)2HQ=-3.3 MeV
Thermal – epithermal peak
(764 keV)
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Counter characteristics Gas Pressure 6 Atm Gas Mixture 3He 65% Kr 33% CO2
2% Diameter 5 cm Effect. length 15 cm Cathode SS304, 0.9 mm Anode Tungsten, 25 μmCd cover 1.2
mm
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Irradiations at the Institute of Nuclear Physics, Demokritos, Athens
Proton Beam: 2.0 – 5.0 MeV 7Li(p, n)7Be En = 0.23 – 3.3 MeV Deuteron Beam: 1.4–7.8 MeV 2H(d, n)3He En = 3.7 – 10.7 MeV
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1 2 3 4 5 64%
68%132%196%260%324%388%452%516%580%644%708%772%836%900%964%
Neutron Energy [MeV]
Reso
lutio
n [%
]
Shap. Time 8 μs
0 500 1000 1500 2000 2500 30001
1,001
2,001
3,001
4,001
5,001
6,001
7,001
Channel
Dep
osite
d E
nerg
y [M
eV]
1500 V 1600 V 1700 V 1800 V
1870 V
NIM A 562(2006) 371 “Studies on the response of He-3 and He-4 proportional counters to monoenergetic fast neutrons“
Full energy peak
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0 200 400 600 800 1000 1200 1400 1600 18000
1
2
3
4
5
6
Channel
Depo
site
d En
ergy
[M
eV]
1500 V 1600 V 1700 V 1800 V
1870 V
Energy calibration of Recoil peak
6
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Comparison of energy calibration for Full-energy and Recoil peaks
0 500 1000 1500 2000 25000
2
4
6
8
Channel
Dep
osite
d En
ergy
[M
eV]
1870 V1700 V
1500 V
7
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Pulse height loss of recoil events
0 1 2 3 4 5 60.0
0.2
0.4
0.6
0.8
1.01500 V1600 V1700 V1800 V1870 V
3He recoil-nucleus energy [MeV]
Δp [
MeV
]
8
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Pulse height loss of recoil events
NIM A 618 (2010) 284-293. “Non linearity of recoil pulse height events in He-3 tubes”
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c
c
E
E
EEEER
EEEdEEEaEaEaaERp
c
030
035430 )1ln)(5.1(0
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0 0.5 1 1.5 2 2.5 31E+00
1E+01
1E+02
1E+03
Neutron Energy [MeV]
Rela
tive
neu
tron
fluen
ce 565 keV1.2 MeV
2.5 MeV
Irradiations at the PTB calibrated neutron field
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Pulse height distributions obtained with He-3 counter
565 keV 1.2 MeV
2.5 MeV
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Geant4 simulation results
0 500 1000 1500 2000 2500 3000 3500 40001
10
100
1000(n,p)Recoil He-3Recoil C,O,Kr,+
Deposited Energy [MeV]
Coun
ts
12
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Simulation results folded with resolution function
0 500 1000 1500 2000 2500 3000 3500 40001
10
100
1000
Deposited Energy [MeV]
Coun
ts
13
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Experimental and simulated spectra
0 500 1000 1500 2000 2500 3000 3500 40001
10
100
1000
10000ExperimentalSimulated Sp.
Deposited Energy [MeV]
Coun
ts
565 keV
1.2 MeV 2.5
MeV
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1E-08 1E-06 1E-04 1E-02 1E+00 1E+02 1E+041E-06
1E-05
1E-04
1E-03
1E-02
Neutron Energy (MeV)
Neu
tron
Flue
nce
(n.c
m-2
.D-1
)
Calculated neutron fluence during irradiation of the extended natU/Pb-assembly with 1.6 GeV deuterons
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Comparison of experimental and simulated spectra
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0 1 2 3 4 5 6 7 8 91
10
100
1000
10000
100000
Experimental SpectrumSimulation results
Deposited Energy [MeV]
Cou
nts
Neutron yield energy distribution
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0.1 1 100
1
2
3
4
5
6
Neutron Energy [MeV]
Neu
trons
/ D
eute
ron
0.10 1.00 10.000
3
6
9
12
15
18He-3 analysisDCM-DEM code
Neutron Energy [MeV]
Neu
trons
/ D
eute
ron
Conclusions He-3 proportional counter response can be simulated with
Geant4 provided that besides the spectrometry functions, recombination coefficient of 3He recoiling nucleus will be determined experimentally.
Using the calculated response with Geant4, neutron energy distribution of a neutron field in the MeV energy region can be determined for the energy range ~ 0.2 – 7 MeV.
No prior knowledge of neutron energy distribution is required.
Thank you for your attention
18VARNA 2011