FPGA-Based Real-Time $n/\gamma$ Discrimination With Liquid Scintillator

A real-time n/y discrimination prototype system based on high-speed waveform sampling and high-performance field-programmable gate array (FPGA) is presented in this paper. In order to accurately record detector signals, a high-speed sampling board with a 14-bit analog-to-digital converter (AD9680) is designed. The BC501A liquid scintillator is employed as the neutron detector, and a discrimination algorithm is implemented in the FPGA of the sampling board. The system is calibrated by
²²
Na,
¹³⁷
Cs, and
⁶⁰
Co y-sources. A PuC neutron source is used to evaluate the discrimination ability. The figure-of-merit of PuC neutron source is determined to be about 1.005 over an energy range of 0-4000 keVee, which is consistent with the test results of the commercial digitizer, and the false alarm rate of
⁶⁰
Co is 0.19%. This system has been successfully applied for the environmental neutron monitoring experiment during the first commissioning of white neutron source tunnel of China spallation neutron source.