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

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.