Performance Calculation of Pulse Shape Discrimination Based on Photoelectron Quantity

Abstract Pulse Shape Discrimination (PSD) is a widely used technique in many experimental analysis. In this study, we specifically aimed to assess the effectiveness of PSD in accurately measuring decay time. We measured the decay times of a 0.1 wt% Gd-loaded liquid scintillator (Gd-LS) with 5 vol% Ultimagold-F added when irradiated with neutrons and gamma rays, which were emitted from a Cf-252 radiation source, using a two-exponential decay model. We distinguished between gamma-like events and neutron-like events using the time-of-flight difference. Based on the measured decay times, we developed a simulation to model the waveforms. In the simulation, we adjusted the number of photoelectrons (NPE) and generated waveforms for NPE ranging from 10 to 1000 photoelectrons. We investigated the pulse shape discrimination (PSD) performance as a function of NPE photoelectrons (PE) and determined that at least 49 PE is required for a neutron-like events rejection efficiency of 90%, while keeping gamma-like events 97.8%.