Microstrip gas chamber with individual read-out using two-level discriminators for neutron detection

摘要

The microstrip gas chamber (MSGC) with an individual read-out and using two-level discriminators for each strip is proposed for neutron detection with a high spatial resolution. The system identifies secondary particles—protons and tritons-created in the nuclear reaction ~3He + n → p + T based on the difference in their track lengths, and determines the incident position of neutrons using suprathreshold signals from tritons. The new system selects the appropriate suprathreshold signals for proper identification from two-level discriminators according to the emission angles of the secondary particles. The calculated spatial resolution of the detector system using the two-level discriminators (Hi-InSPaD) was 0.5mm in full width at half maximum when the MSGC was operated in a gas condition of a mixture of 20% argon with helium-3 at 0.5 MPa, when the strip pitches were 0.4 mm in both x and y axes. The calculated spatial response of the detector to the point-incident neutrons was superior to a standard InSPaD system that uses one level of threshold discrimination, in terms of the peak counts (about twofold higher) and the peak shape and width.