A Study on the Impact of Pulse Shaping Parameters on Zero-Crossing Method Performance for Neutron/Gamma Discrimination

This work examines the relationship between the pulse shaping time parameters, namely the integral and differential constants, and the ability of the zero-crossing (ZC) method to perform the neutron/gamma pulse shape discrimination (PSD). To mitigate the impact of various noise sources, such as the preamplifier, we developed a simulation model with adjustable shaping time parameters and applied it to evaluate the effects of shaping time parameters on neutron/gamma discrimination capability. Experimental radiation pulses were collected using a system comprised of an EJ-301 scintillator detector coupled with a Hamamatsu R9420 photomultiplier (PMT) and a DRS4 digitizer, along with 252Cf,60Co, and 137Cs radioactive sources. In total, we have surveyed multiple quality factors of the ZC method, namely the figure of merit (FoM), discriminant quality function [F(u)], and misidentification ratio, as a function of integral and differential time constants ranging from 1 to 160 ns. The results indicate that the ZC method provides optimal quality for the EJ-301 scintillator detector when the differential and integral constants are set within the ranges of 80 to 100 ns and 40 to 80 ns, respectively. Additionally, the relationships between various PSD quality factors and the pulse shaping parameters vary. Consequently, it is necessary to simultaneously examine multiple PSD quality factors concerning pulse shaping parameters to determine their optimal values.