Recent Developments in Fast Neutron Detection and Multiplicity Counting with Liquid Scintillator

Journal Article · Tue Dec 13 04:00:00 EST 2011 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3665320· OSTI ID:22003921

Nakae, L F; Chapline, G F; Glenn, A M; Kerr, P L; Kim, K S; Ouedraogo, S A; Prasad, M K; Sheets, S A; Snyderman, N J; Verbeke, J M; Wurtz, R E ^[1]

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1. Lawrence Livermore National Laboratory, Livermore, California (United States)

For many years, LLNL researchers have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of the techniques have been developed specifically for the relatively low efficiency (a few percent) attainable by detector systems limited to man-portability. Historically, thermal neutron detectors (mainly {sup 3}He) were used, taking advantage of the high thermal neutron interaction cross sections. More recently, we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics that respond over 1000 times faster (ns versus tens of {mu}s) than thermal neutron detectors. Fast neutron detection offers considerable advantages since the inherent ns production timescales of spontaneous fission and neutron-induced fission are preserved and measured instead of being lost by thermalization required for thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of fast portable digital electronics as well as faster and less hazardous scintillator formulations. Faster detector response times and sensitivity to neutron momentum show promise for measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed fission sources like Cm and Pu. We report on measured results with our existing liquid scintillator array and progress on the design of a nuclear material assay system that incorporates fast neutron detection, including the surprising result that fast liquid scintillator detectors become competitive and even surpass the precision of {sup 3}He-based counters measuring correlated pairs in modest (kg) samples of plutonium.

• OSTI ID: 22003921
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1412; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CROSS SECTIONS
EFFICIENCY
FAST NEUTRONS
GAMMA RADIATION
HE-3 COUNTERS
LAWRENCE LIVERMORE NATIONAL LABORATORY
LIQUID SCINTILLATION DETECTORS
MULTIPLICITY
NEUTRON DETECTION
PLUTONIUM
SCINTILLATION COUNTERS
SENSITIVITY
SPALLATION
SPONTANEOUS FISSION
THERMAL NEUTRONS
THERMALIZATION