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Title: Pillar-structured neutron detector based multiplicity system

Abstract

This work demonstrates the potential of silicon pillars filled with boron-10 as a sensor technology for a compact and portable neutron multiplicity system. Solid-state, semiconductor based neutron detectors may enable completely new detector form factors, offer an alternate approach to helium-3 based systems, and reduce detector weight and volume requirements. Thirty-two pillar-structured neutron detectors were assembled into a system with an active area of over 20 cm 2 and were used in this work to demonstrate the feasibility of this sensor technology as a potential replacement for helium-3 based gas detectors. Multiplicity measurements were successfully carried out using a californium-252 neutron source, in which the source mass, system efficiency, and die-away time were determined. As a result, this demonstration shows that these solid-state detectors could allow for a more compact and portable system that could be used for special nuclear material identification in the field.

Authors:
 [1];  [1];  [1];  [1];  [2];  [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1418939
Report Number(s):
LLNL-JRNL-734176
Journal ID: ISSN 0168-9002
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Journal Information:
Journal Volume: 877; Journal Issue: C; Journal ID: ISSN 0168-9002
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 98 NUCLEAR DISARMAMENT, SAFEGUARDS AND PHYSICAL PROTECTION; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Murphy, John W., Shao, Qinghui, Voss, Lars F., Kerr, Phil L., Fabris, Lorenzo, Conway, Adam M., and Nikolic, Rebecca J. Pillar-structured neutron detector based multiplicity system. United States: N. p., 2017. Web. doi:10.1016/j.nima.2017.09.060.
Murphy, John W., Shao, Qinghui, Voss, Lars F., Kerr, Phil L., Fabris, Lorenzo, Conway, Adam M., & Nikolic, Rebecca J. Pillar-structured neutron detector based multiplicity system. United States. doi:10.1016/j.nima.2017.09.060.
Murphy, John W., Shao, Qinghui, Voss, Lars F., Kerr, Phil L., Fabris, Lorenzo, Conway, Adam M., and Nikolic, Rebecca J. 2017. "Pillar-structured neutron detector based multiplicity system". United States. doi:10.1016/j.nima.2017.09.060.
@article{osti_1418939,
title = {Pillar-structured neutron detector based multiplicity system},
author = {Murphy, John W. and Shao, Qinghui and Voss, Lars F. and Kerr, Phil L. and Fabris, Lorenzo and Conway, Adam M. and Nikolic, Rebecca J.},
abstractNote = {This work demonstrates the potential of silicon pillars filled with boron-10 as a sensor technology for a compact and portable neutron multiplicity system. Solid-state, semiconductor based neutron detectors may enable completely new detector form factors, offer an alternate approach to helium-3 based systems, and reduce detector weight and volume requirements. Thirty-two pillar-structured neutron detectors were assembled into a system with an active area of over 20 cm2 and were used in this work to demonstrate the feasibility of this sensor technology as a potential replacement for helium-3 based gas detectors. Multiplicity measurements were successfully carried out using a californium-252 neutron source, in which the source mass, system efficiency, and die-away time were determined. As a result, this demonstration shows that these solid-state detectors could allow for a more compact and portable system that could be used for special nuclear material identification in the field.},
doi = {10.1016/j.nima.2017.09.060},
journal = {Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment},
number = C,
volume = 877,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on October 4, 2018
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  • This work reports numerical simulations of a novel three-dimensionally integrated, {sup 10}boron ({sup 10}B) and silicon p+, intrinsic, n+ (PIN) diode micropillar array for thermal neutron detection. The inter-digitated device structure has a high probability of interaction between the Si PIN pillars and the charged particles (alpha and {sup 7}Li) created from the neutron - {sup 10}B reaction. In this work, the effect of both the 3-D geometry (including pillar diameter, separation and height) and energy loss mechanisms are investigated via simulations to predict the neutron detection efficiency and gamma discrimination of this structure. The simulation results are demonstrated tomore » compare well with the measurement results. This indicates that upon scaling the pillar height, a high efficiency thermal neutron detector is possible.« less
  • Current helium-3 tube based thermal neutron detectors have shortcomings in achieving simultaneously high efficiency and low voltage while maintaining adequate fieldability performance. By using a three-dimensional silicon p-i-n diode pillar array filled with boron-10 these constraints can be overcome. The fabricated pillar structured detector reported here is composed of 2 {mu}m diameter silicon pillars with a 4 {mu}m pitch and height of 12 {mu}m. A thermal neutron detection efficiency of 7.3+/-0.6% and a neutron-to-gamma discrimination of 10{sup 5} at 2 V reverse bias were measured for this detector. When scaled to larger aspect ratio, a high efficiency device is possible.
  • Silicon pillar structures filled with a neutron converter material ( 10B) are designed to have high thermal neutron detection efficiency with specific dimensions of 50 μm pillar height, 2 μm pillar diameter and 2 μm spacing between adjacent pillars. In this paper, we have demonstrated such a detector has a high neutron-to-gamma discrimination of 10 6 with a high thermal neutron detection efficiency of 39% when exposed to a high gamma-ray field of 10 9 photons/cm 2s.
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