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The distribution of neutrons and gamma-rays in mixed fields is a main interest in pulse shape discrimination (PSD) studies, and becomes more significant when it involves techniques such as machine learning which requires true data. One of the surest methods to label neutrons and gamma-rays is neutron Time-of-Flight. This can be applied to the identification of special nuclear materials and by extension to nuclear non-proliferation. Moreover, the integration of silicon photomultiplier (SiPM) technology can make the neutron Time-of-Flight system more compact. Two EJ-276 plastic scintillators, which are capable of PSD, were coupled to SiPMs. The actual portion of neutrons from a 252Cf source intruding the gamma-rays in PSD ratio distribution, labeled by neutron Time-of-Flight, was calculated and then compared with gamma-rejection ratio (GRR) for each threshold in SiPM-based pulse shape discrimination. [ABSTRACT FROM AUTHOR]

This study conducted an initial experimental investigation to compare the performance of the charge comparison (CC) and constant fraction time-over-threshold (CF-TOT) methods under various operating conditions. In this study, the influence of overvoltage exhibited tendencies according to the method used, though generally, a high overvoltage did not guarantee superior performance in pulse shape discrimination (PSD). Moreover, the results of the CC method consistently demonstrated PSD performance irrespective of operating conditions, including apparatus configuration, operating voltage, and temperature. Conversely, the CF-TOT method showed significant improvement, particularly in the low electron equivalent region, by employing external equipment or controlling the experimental conditions to mitigate noise factors. We believe that this research will not only contribute to enhancing particle classification performance under low-temperature conditions by proposing the utilization of the CF-TOT method but will also facilitate the optimization of SiPM-based systems for PSD. [ABSTRACT FROM AUTHOR]