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Title: Intense Photoneutron Sources For Nuclear Material Detection

Abstract

Intense neutron sources are essential for cargo inspection for a broad range of threats from explosives, to contraband, to nuclear materials and especially SNM (Special Nuclear Materials). To be effective over a wide range of cargo materials, in particular for hydrogenous cargo such as food, and to offer practical inspection times, the neutron source must be very strong, typically >10{sup 10} neutrons per second. Unfortunately there are currently no reasonably compact and economical neutron generators with the required intensities. The insufficiency and inadequacy of intense neutron sources are especially conspicuous in the {<=}2.5 MeV range (low voltage (d,D) generator). This energy range is needed if the strong signature of prompt fission neutrons ({approx_equal}3 per fission) is to be detected and discerned from the numerous source neutrons. The photonuclear reactions of x-rays from commercial linacs in appropriate converters can provide ample intensities of neutrons. These converters have a very low ({gamma},n) energy threshold: 1.67 MeV for beryllium and 2.23 MeV for deuterium. The intense x-ray beams provided by commercial x-ray systems, more than compensate for the relatively low ({gamma},n) cross-sections which are in the milli-barn range. The choice of converter material, the geometrical shape, dimensions and location relative to the x-raymore » source, determine the efficiency of the neutron conversion. For electron accelerators with less than 10 MeV, the preferred converters, Be and D{sub 2}O, are also very good neutron moderators. Thus, while increasing the converters' thickness leads to an increase in the overall neutron yield, this causes the softening of the neutron spectrum, which reduces the neutron penetration especially in hydrogenous cargos. Photoneutron sources can be optimized to meet specific needs such as maximum fission signals in various cargo materials of interest. Efficient photoneutron sources with different energy spectra were investigated. Conversion efficiency of more than 10-4 neutron per 9 MeV electron yielding neutron intensities of more than 10{sup 11} n/s for commercial 100 {mu}Amp electron accelerators has been modeled and designed. The simulation was validated in laboratory experiments using small Be and D{sub 2}O converters.« less

Authors:
; ;  [1]
  1. Rapiscan Laboratories, Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States)
Publication Date:
OSTI Identifier:
21513449
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 1336; Journal Issue: 1; Conference: CAARI 2010: 21. International Conference on the Application of Accelerators in Research and Industry, Fort Worth, TX (United States), 8-13 Aug 2010; Other Information: DOI: 10.1063/1.3586192; (c) 2011 American Institute of Physics; Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 43 PARTICLE ACCELERATORS; BEAMS; BERYLLIUM; CARGO; CROSS SECTIONS; DEUTERIUM; ELECTRONS; ENERGY SPECTRA; EXPLOSIVES; FISSION; FISSION NEUTRONS; HEAVY WATER; LINEAR ACCELERATORS; MEV RANGE 01-10; NEUTRON GENERATORS; NEUTRON SPECTRA; PHOTONUCLEAR REACTIONS; SIMULATION; X RADIATION; X-RAY SOURCES; ACCELERATORS; ALKALINE EARTH METALS; BARYONS; DEUTERIUM COMPOUNDS; ELECTROMAGNETIC RADIATION; ELEMENTARY PARTICLES; ELEMENTS; ENERGY RANGE; FERMIONS; HADRONS; HYDROGEN COMPOUNDS; HYDROGEN ISOTOPES; IONIZING RADIATIONS; ISOTOPES; LEPTONS; LIGHT NUCLEI; METALS; MEV RANGE; NEUTRON SOURCES; NEUTRONS; NUCLEAR REACTIONS; NUCLEI; NUCLEONS; ODD-ODD NUCLEI; OXYGEN COMPOUNDS; PARTICLE SOURCES; RADIATION SOURCES; RADIATIONS; SPECTRA; STABLE ISOTOPES; WATER

Citation Formats

Gozani, Tsahi, Shaw, Timothy, and King, Michael. Intense Photoneutron Sources For Nuclear Material Detection. United States: N. p., 2011. Web. doi:10.1063/1.3586192.
Gozani, Tsahi, Shaw, Timothy, & King, Michael. Intense Photoneutron Sources For Nuclear Material Detection. United States. https://doi.org/10.1063/1.3586192
Gozani, Tsahi, Shaw, Timothy, and King, Michael. Wed . "Intense Photoneutron Sources For Nuclear Material Detection". United States. https://doi.org/10.1063/1.3586192.
@article{osti_21513449,
title = {Intense Photoneutron Sources For Nuclear Material Detection},
author = {Gozani, Tsahi and Shaw, Timothy and King, Michael},
abstractNote = {Intense neutron sources are essential for cargo inspection for a broad range of threats from explosives, to contraband, to nuclear materials and especially SNM (Special Nuclear Materials). To be effective over a wide range of cargo materials, in particular for hydrogenous cargo such as food, and to offer practical inspection times, the neutron source must be very strong, typically >10{sup 10} neutrons per second. Unfortunately there are currently no reasonably compact and economical neutron generators with the required intensities. The insufficiency and inadequacy of intense neutron sources are especially conspicuous in the {<=}2.5 MeV range (low voltage (d,D) generator). This energy range is needed if the strong signature of prompt fission neutrons ({approx_equal}3 per fission) is to be detected and discerned from the numerous source neutrons. The photonuclear reactions of x-rays from commercial linacs in appropriate converters can provide ample intensities of neutrons. These converters have a very low ({gamma},n) energy threshold: 1.67 MeV for beryllium and 2.23 MeV for deuterium. The intense x-ray beams provided by commercial x-ray systems, more than compensate for the relatively low ({gamma},n) cross-sections which are in the milli-barn range. The choice of converter material, the geometrical shape, dimensions and location relative to the x-ray source, determine the efficiency of the neutron conversion. For electron accelerators with less than 10 MeV, the preferred converters, Be and D{sub 2}O, are also very good neutron moderators. Thus, while increasing the converters' thickness leads to an increase in the overall neutron yield, this causes the softening of the neutron spectrum, which reduces the neutron penetration especially in hydrogenous cargos. Photoneutron sources can be optimized to meet specific needs such as maximum fission signals in various cargo materials of interest. Efficient photoneutron sources with different energy spectra were investigated. Conversion efficiency of more than 10-4 neutron per 9 MeV electron yielding neutron intensities of more than 10{sup 11} n/s for commercial 100 {mu}Amp electron accelerators has been modeled and designed. The simulation was validated in laboratory experiments using small Be and D{sub 2}O converters.},
doi = {10.1063/1.3586192},
url = {https://www.osti.gov/biblio/21513449}, journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 1336,
place = {United States},
year = {2011},
month = {6}
}