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

A gas-based neutron detection system with individual readout method and comprising a micro-pixel detector head was constructed, and preliminary experiments were conducted under neutrons irradiation. The detection system also consisted of a micro-pixel detector head, a gas chamber that had feedthrough lines of 541 channels, amplifier-shaper-discriminator boards, position encoders with field programmable gate arrays, and a device capable of fast data acquisition. The micro-pixel detector head exhibited a fast response time, and the full width at half maximum of the response time was 160 ns. Its gas gain was about 50 at an anode-cathode voltage of 560 V and a gas pressure of 0.5 MPa (0.45 MPa for He and 0.05 MPa for CF4). Signal pulse peaks of neutrons could be identified and their output voltages at an anode and a cathode were 2.4 and 5.3 mV, respectively; on the other hand, the output voltage of all the anodes was 105 mV. The neutron detection system could easily distinguish neutron signals from the background noise, and the gas gain of the micro-pixel detector head did not changed.