Measurement of rays from LiF tile as an inner wall of a neutron-decay detector

Koga, Jun*; Kimura, Atsushi   ; Okudaira, Takuya*; 12 of others*

A neutron lifetime measurement conducted at the Japan Proton Accelerator Research Complex (J-PARC) is counting the number of electrons from neutron decays with a time projection chamber (TPC). The rays produced in the TPC cause irreducible background events. To achieve the precise measurement, the inner walls of the TPC consist of Li-enriched lithium-fluoride (LiF) tiles to suppress the amount of rays. In order to estimate the amount of rays from the LiF tile, prompt ray measurements were performed using germanium detectors. We reconstructed the measured -ray energy spectrum using a Monte Carlo simulation. We concluded that the amount of rays produced from the LiF tile is not more twice the originally assumed value.