Neutron detection in a high-gamma field using solution-grown stilbene

Journal Article · 19 October 2015 · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

DOI: https://doi.org/10.1016/j.nima.2015.10.025 · OSTI ID:1487036

Bourne, M. M. ^[1]; Clarke, S. D. ^[1]; Adamowicz, N. ^[1]; Pozzi, S. A. ^[1]; Zaitseva, N. ^[2]; Carman, L. ^[2]

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1. Univ. of Michigan, Ann Arbor, MI (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

We present that a solution-based technique for growing large-volume stilbene scintillators was developed in 2013; crystals up to diameters of 10 cm, or larger, have been grown while preserving excellent pulse shape discrimination (PSD) properties. The goal of this study is to evaluate the PSD capabilities of 5.08 by 5.08-cm stilbene crystals grown by Lawrence Livermore National Laboratory and Inrad Optics when exposed to a 1000 to 1 gamma ray-neutron ratio and operating at a 100-kHz count rate. Results were compared to an equivalent EJ-309 liquid scintillation detector. ²⁵²Cf neutron pulses were recorded in two experiments where ⁶⁰Co and ¹³⁷Cs sources created the high-gamma field. The high count rate created numerous double pulses that were cleaned using fractional and template approaches designed to remove double pulses while preserving neutron counts. PSD was performed at a threshold of 42 keVee (440-keV proton) for stilbene and 60 keVee (610-keV proton) for EJ-309 liquid. The lower threshold in stilbene resulted in a neutron intrinsic efficiency of approximately 14.5%, 10% higher than EJ-309 liquid, for bare ²⁵²Cf and 13% for ²⁵²Cf in the high-gamma field. Despite the lower threshold, the gamma misclassification rate in stilbene was approximately 3×10^$$-$$6, nearly a factor-of-five lower than what we found with the EJ-309 liquid.

• Research Organization: Univ. of Michigan, Ann Arbor, MI (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation
• Grant/Contract Number: NA0002534
• OSTI ID: 1487036
• Alternate ID(s): OSTI ID: 1397529
• Journal Information: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 806, Issue C; ISSN 0168-9002
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English