Flat-response neutron detector using spatial distribution of thermal neutrons in a moderator

Abstract

We propose a novel neutron detector that realized flat-response using information of a spatial distribution of thermal neutrons in a moderator. The proposed detector consists of a 3He position sensitive proportional counter (PSPC) and a cylindrical moderator surrounding the 3He PSPC. The cylindrical detector is irradiated by neutrons along the cylinder axis. The spatial response of the 3He PSPC is used to correct the detector response into flat-response. We adopt a weighting method to achieve flat-response, in which detected neutrons weighted depending on their detected positions are accumulated as the detector response. Through Monte Carlo simulation studies, we confirm that the flat-response neutron detector can be realized by correcting the response of the proposed detector using the weights determined by a multiple least square method (MLSM). Additionally, fundamental property of the 3He PSPC is experimentally investigated to check applicability to the proposed flat-response neutron detector. We conclude that we should take account of the end effect when determining the weights and correcting the detector response.