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Investigation and optimisation of mobile Nal(Tl) and He-3-based neutron detectors for finding point sources

Nilsson, Jonas LU ; Finck, Robert LU and Rääf, Christopher LU (2015) In Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment 786. p.127-134
Abstract
Neutron radiation produces high-energy gamma radiation through (n,gamma) reactions in matter. This can be used to detect neutron sources indirectly using gamma spectrometers. The sensitivity of a gamma spectrometer to neutrons can be amplified by surrounding it with polyvinyl chloride (PVC). The hydrogen in the PVC acts as a moderator and the chlorine emits prompt gammas when a neutron is captured. A 4.7-l He-3-based mobile neutron detector was compared to a 4-1 NOM-detector covered with PVC using this principle. Methods were also developed to optimise the measurement parameters of the systems. The detector systems were compared with regard to their ability to find (AmBe)-Am-241, (CI)-C-252 and Pu-238-C-13 neutron sources. Results from... (More)
Neutron radiation produces high-energy gamma radiation through (n,gamma) reactions in matter. This can be used to detect neutron sources indirectly using gamma spectrometers. The sensitivity of a gamma spectrometer to neutrons can be amplified by surrounding it with polyvinyl chloride (PVC). The hydrogen in the PVC acts as a moderator and the chlorine emits prompt gammas when a neutron is captured. A 4.7-l He-3-based mobile neutron detector was compared to a 4-1 NOM-detector covered with PVC using this principle. Methods were also developed to optimise the measurement parameters of the systems. The detector systems were compared with regard to their ability to find (AmBe)-Am-241, (CI)-C-252 and Pu-238-C-13 neutron sources. Results from stationary measurements were used to calculate optimal integration times as well as minimum detectable neutron emission rates. It was found that the 3He-based detector was more sensitive to Cf-252 sources whereas the Nal(TI) detector was more sensitive to (AmBe)-Am-241 and Pu-238-C-13 sources. The results also indicated that the sensitivity of the detectors to sources at known distances could theoretically be improved by 60% by changing from fixed integration times to list mode in mobile surveys. (C) 2015 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Gamma radiation, Neutron radiation, Mobile, Nal(TI), He-3
in
Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment
volume
786
pages
127 - 134
publisher
Elsevier
external identifiers
  • wos:000353068600019
  • scopus:84926358190
ISSN
0167-5087
DOI
10.1016/j.nima.2015.03.013
language
English
LU publication?
yes
id
b3c18afb-2a23-497a-92f1-63f59abc981c (old id 5385950)
date added to LUP
2015-05-18 13:41:06
date last changed
2017-01-01 05:49:20
@article{b3c18afb-2a23-497a-92f1-63f59abc981c,
  abstract     = {Neutron radiation produces high-energy gamma radiation through (n,gamma) reactions in matter. This can be used to detect neutron sources indirectly using gamma spectrometers. The sensitivity of a gamma spectrometer to neutrons can be amplified by surrounding it with polyvinyl chloride (PVC). The hydrogen in the PVC acts as a moderator and the chlorine emits prompt gammas when a neutron is captured. A 4.7-l He-3-based mobile neutron detector was compared to a 4-1 NOM-detector covered with PVC using this principle. Methods were also developed to optimise the measurement parameters of the systems. The detector systems were compared with regard to their ability to find (AmBe)-Am-241, (CI)-C-252 and Pu-238-C-13 neutron sources. Results from stationary measurements were used to calculate optimal integration times as well as minimum detectable neutron emission rates. It was found that the 3He-based detector was more sensitive to Cf-252 sources whereas the Nal(TI) detector was more sensitive to (AmBe)-Am-241 and Pu-238-C-13 sources. The results also indicated that the sensitivity of the detectors to sources at known distances could theoretically be improved by 60% by changing from fixed integration times to list mode in mobile surveys. (C) 2015 Elsevier B.V. All rights reserved.},
  author       = {Nilsson, Jonas and Finck, Robert and Rääf, Christopher},
  issn         = {0167-5087},
  keyword      = {Gamma radiation,Neutron radiation,Mobile,Nal(TI),He-3},
  language     = {eng},
  pages        = {127--134},
  publisher    = {Elsevier},
  series       = {Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment},
  title        = {Investigation and optimisation of mobile Nal(Tl) and He-3-based neutron detectors for finding point sources},
  url          = {http://dx.doi.org/10.1016/j.nima.2015.03.013},
  volume       = {786},
  year         = {2015},
}