Development of a bump cathode element for two-dimensional neutron detection

A neutron-detection element using circular cathode bumps was developed for two-dimensional neutron measurement, and an irradiation experiment was performed using a Cf-252 neutron source. The element has triangularly arranged small-sized circular cathode bumps, and the bumps are linked together in the x- and y-directions for the detection of incident neutrons. Preliminary irradiation experiments for the developed element were performed using a neutron-detection system consisting of a pressure vessel, amplifier-shaper-discriminator boards, optical signal transmission devices, position encoders, and a data acquisition device. The element was arranged in the pressure vessel with a fill gas of composition He/(15%)CF₄ at 0.7 MPa. The detector system exhibited a two-dimensional uniformity with a response of 10.1%. The average intrinsic spatial resolution was 1.89 mm full width at half maximum in the sensitive region, calculated by taking into account the track lengths of the secondary particles.