Observation of neutron-induced signals with two-dimensional micro-pixel gas chamber

To, Kentaro  ; Yamagishi, Hideshi; Sakasai, Kaoru  ; Nakamura, Tatsuya  ; Soyama, Kazuhiko  

A gas-based neutron detection system with individual readout capability and consisting of a micro-pixel detector array was constructed, and preliminary experiments using a Cf-252 neutron source and JRR-3 fission reactor were conducted. The detector array exhibited a fast temporal response and the full width at half maximum (FWHM) of the response time was 160 ns. The gas gain was about 50 at a supplied anode-cathode voltage of 560 V and a gas pressure of 5 atm. Signal pulse peaks of neutrons could be identified and their output voltages at an anode and a cathode are 2.4 and 5.3 mV, respectively, while the output voltage of all anodes is 105 mV. The micro-pixel gas chamber system easily discriminated neutron signals from background noises, and there was no degradation of the gas gain due to a charge up effect.