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Title: Coated gallium arsenide neutron detectors : results of characterizationmeasurements.

Abstract

Effective detection of special nuclear materials (SNM) is essential for reducing the threat associated with stolen or improvised nuclear devices. Passive radiation detection technologies are primarily based on gamma-ray detection and subsequent isotope identification or neutron detection (specific to neutron sources and SNM). One major effort supported by the Department of Homeland Security in the area of advanced passive detection is handheld or portable neutron detectors for search and localization tasks in emergency response and interdiction settings. A successful SNM search detector will not only be able to confirm the presence of fissionable materials but also establish the location of the source in as short of time as possible while trying to minimize false alarms due to varying background or naturally occurring radioactive materials (NORM). For instruments based on neutron detectors, this translates to detecting neutrons from spontaneous fission or alpha-n reactions and being able to determine the direction of the source (or localizing the source through subsequent measurements). Polyethylene-coated gallium arsenide detectors were studied because the detection scheme is based on measuring the signal in the gallium arsenide wafers from the electrical charge of the recoil protons produced from the scattering of neutrons from the hydrogen nucleus. The inherentmore » reaction has a directional dependence because the neutron and hydrogen nucleus have equivalent masses. The assessment and measurement of polyethylene-coated gallium arsenide detector properties and characteristics was the first phase of a project being performed for the Department of Homeland Security and the results of these tests are reported in this report. The ultimate goal of the project was to develop a man-portable neutron detection system that has the ability to determine the direction of the source from the detector. The efficiency of GaAs detectors for different sizes of polyethylene layers and different angles between the detector and the neutron source were determined. Preliminary measurements with a neutron generator based on a deuterium-tritium reaction ({approx}14 MeV neutrons) were performed and the results are discussed. This report presents the results of these measurements in terms of efficiency and angular efficiency and compares them to Monte Carlo calculations to validate the calculation scheme in view of further applications. Based on the results of this study, the polyethylene-coated gallium arsenide detectors provide adequate angular resolution based on proton recoil detection from the neutron scattering reaction from hydrogen. However, the intrinsic efficiency for an individual detector is extremely low. Because of this low efficiency, large surface area detectors ( or a large total surface area from many small detectors) would be required to generate adequate statistics to perform directional detection in near-real time. Large surface areas could be created by stacking the detector wafers with only a negligible attenuation of source neutrons. However, the cost of creating such a large array of GaAs is cost-prohibitive at this time.« less

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
898524
Report Number(s):
ANL-06/42
TRN: US0701916
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Technical Report
Country of Publication:
United States
Language:
ENGLISH
Subject:
08 HYDROGEN; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; DETECTION; EFFICIENCY; FISSIONABLE MATERIALS; GALLIUM ARSENIDES; HYDROGEN; NEUTRON DETECTION; NEUTRON DETECTORS; NEUTRON GENERATORS; NEUTRON SOURCES; NEUTRONS; POLYETHYLENES; PROTONS; RADIATION DETECTION; RADIOACTIVE MATERIALS; RESOLUTION; SPONTANEOUS FISSION; STATISTICS; SURFACE AREA

Citation Formats

Klann, R T, Perret, G, and Sanders, J. Coated gallium arsenide neutron detectors : results of characterizationmeasurements.. United States: N. p., 2006. Web. doi:10.2172/898524.
Klann, R T, Perret, G, & Sanders, J. Coated gallium arsenide neutron detectors : results of characterizationmeasurements.. United States. https://doi.org/10.2172/898524
Klann, R T, Perret, G, and Sanders, J. 2006. "Coated gallium arsenide neutron detectors : results of characterizationmeasurements.". United States. https://doi.org/10.2172/898524. https://www.osti.gov/servlets/purl/898524.
@article{osti_898524,
title = {Coated gallium arsenide neutron detectors : results of characterizationmeasurements.},
author = {Klann, R T and Perret, G and Sanders, J},
abstractNote = {Effective detection of special nuclear materials (SNM) is essential for reducing the threat associated with stolen or improvised nuclear devices. Passive radiation detection technologies are primarily based on gamma-ray detection and subsequent isotope identification or neutron detection (specific to neutron sources and SNM). One major effort supported by the Department of Homeland Security in the area of advanced passive detection is handheld or portable neutron detectors for search and localization tasks in emergency response and interdiction settings. A successful SNM search detector will not only be able to confirm the presence of fissionable materials but also establish the location of the source in as short of time as possible while trying to minimize false alarms due to varying background or naturally occurring radioactive materials (NORM). For instruments based on neutron detectors, this translates to detecting neutrons from spontaneous fission or alpha-n reactions and being able to determine the direction of the source (or localizing the source through subsequent measurements). Polyethylene-coated gallium arsenide detectors were studied because the detection scheme is based on measuring the signal in the gallium arsenide wafers from the electrical charge of the recoil protons produced from the scattering of neutrons from the hydrogen nucleus. The inherent reaction has a directional dependence because the neutron and hydrogen nucleus have equivalent masses. The assessment and measurement of polyethylene-coated gallium arsenide detector properties and characteristics was the first phase of a project being performed for the Department of Homeland Security and the results of these tests are reported in this report. The ultimate goal of the project was to develop a man-portable neutron detection system that has the ability to determine the direction of the source from the detector. The efficiency of GaAs detectors for different sizes of polyethylene layers and different angles between the detector and the neutron source were determined. Preliminary measurements with a neutron generator based on a deuterium-tritium reaction ({approx}14 MeV neutrons) were performed and the results are discussed. This report presents the results of these measurements in terms of efficiency and angular efficiency and compares them to Monte Carlo calculations to validate the calculation scheme in view of further applications. Based on the results of this study, the polyethylene-coated gallium arsenide detectors provide adequate angular resolution based on proton recoil detection from the neutron scattering reaction from hydrogen. However, the intrinsic efficiency for an individual detector is extremely low. Because of this low efficiency, large surface area detectors ( or a large total surface area from many small detectors) would be required to generate adequate statistics to perform directional detection in near-real time. Large surface areas could be created by stacking the detector wafers with only a negligible attenuation of source neutrons. However, the cost of creating such a large array of GaAs is cost-prohibitive at this time.},
doi = {10.2172/898524},
url = {https://www.osti.gov/biblio/898524}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2006},
month = {9}
}