Testing the performance of a two-dimensional microstrip gas chamber by measuring ranges of secondary particles in the He(n,p) reaction

Tanaka, Hiroki; Nakamura, Tatsuya  ; Yamagishi, Hideshi; Soyama, Kazuhiko  ; Aizawa, Kazuya  ; Tanimori, Toru*; Ochi, Atsuhiko*

We have been developing a two-dimensional microstrip gas chamber for neutron scattering experiments such as reflectometer and small-angle neutron scattering for the intense pulsed neutron source at JSNS. Our detection system comprises a gas vessel that can operate up to 10 atm, four amplifier-shaper-discriminator boards that provide 128 128 individual readouts, an encoding system to determine neutron incident positions, and a data display device. The developed system digitally calculates the incident position of a neutron as the centroid of the "hit-channels" to ensure fast neutron counting and imaging. To examine the performance of the developed detector system, the total range of the secondary particles emitted by the nuclear reaction between neutrons and He nuclei was evaluated by irradiating a detection area of 55 cm under the gas condition of 6.6-atm He(He partial pressure of 0.52 atm) with 1.4-atm CF. We confirmed that the measured hit-channel distribution agreed with the Monte Carlo simulated results. The detector exhibited a spatial resolution of 1.5 mm in each axis direction, as measured using the collimated cold-neutron beam.