FPGA implementation of 500-MHz high-count-rate high-time-resolution real-time digital neutron-gamma discrimination for fast liquid detectors

Fast neutron flux measurements with high count rates and high time resolution have important applications in equipment such as tokamaks. In this study, real-time neutron and gamma discrimination was implemented on a self-developed 500-Msps, 12-bit digitizer, and the neutron and gamma spectra were calculated directly on an FPGA. A fast neutron flux measurement system with BC-501A and EJ-309 liquid scintillator detectors was developed and a fast neutron measurement experiment was successfully performed on the HL-2 M tokamak at the Southwestern Institute of Physics, China. The experimental results demonstrated that the system obtained the neutron and gamma spectra with a time accuracy of 1 ms. At count rates of up to 1 Mcps, the figure of merit was greater than 1.05 for energies between 50 keV and 2.8 MeV