Position-dependent neutron detection efficiency loss in 3He gas proportional counters

Published

August 22, 2020

Author(s)

Patrick N. Peplowski, Zachary W. Yokley, Madison Liebel, Shuo Cheng, Richard C. Elphic, Shannon Hoogerheide, David J. Lawrence, Jeffrey Nico

Abstract

The position-dependent neutron detection response of a 3He gas proportional counter (GPC) was characterized using a collimated (3-mm-wide), monoenergetic 0.05 eV neutron beam. For neutrons incident on the GPC near the ends of the active region, the neutron capture peak broadens and the position shifts to lower pulse-height channels. This "edge effect" is due to lower gas gain within the decreasing electric field near the end of the active volume. For simple peak-region-summing analyses, the consequence is a reduction in the total neutron detection efficiency. For our specific GPC, we observed a 13% reduction in the active area of the sensor. Summing over all events above the triton wall-effect feature significantly reduces this efficiency loss. Whole-sensor illumination measurements simulated with Geant4 required a correction for the edge effect to accurately reproduce the shape and amplitude of the measurements. Once these corrections are applied, the Geant4 models reproduce the whole-sensor count rates to within 10%.

Citation

Nuclear Instruments and Methods in Physics Research A

Volume

982

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.nima.2020.164574

Local Download

Keywords

Neutron detection, 3He gas proportional counter, Neutron efficiency

Citation

Peplowski, P. , Yokley, Z. , Liebel, M. , Cheng, S. , Elphic, R. , Hoogerheide, S. , Lawrence, D. and Nico, J. (2020), Position-dependent neutron detection efficiency loss in 3He gas proportional counters, Nuclear Instruments and Methods in Physics Research A, [online], https://doi.org/10.1016/j.nima.2020.164574, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930073 (Accessed October 9, 2025)