Optimization of the Charge Comparison Method for Multiradiation Field Using Various Measurement Systems

Abstract

This article presents a procedure for optimizing the charge comparison method (CCM) used for pulse shape discrimination (PSD). Without prior knowledge of the signals or the readout system, our procedure automatically optimizes the integration periods maximizing the discrimination ability of the radiation detector. This procedure is innovative in its adaptability and automation without being complicated to implement on a standard computer. Another advantage of this approach is the possibility to use it even if the operation of the readout system and the recording process of the signal is not fully known. Therefore, it enables all detection systems generating signals whose temporal evolution depends on the origin to optimize the integration periods of the CCM. Our procedure is based on verifying that two criteria are met in terms of the number of components and the correlation of Gaussian fits made on the distribution of the tail-to-total integral resulting from the CCM. We tested the procedure for different application cases. First, the optimization of the integration periods of the CCM was performed for the discrimination between fast neutrons and gamma rays with a plastic scintillator and a silicon photomultiplier (SiPM) in the energy range [250 keVee; 4.5 MeVee]. The integration periods, from the laboratory’s experience with photomultiplier tubes (PMTs) and plastic scintillators, gave a Figure of Merit (FoM) of 0.58 corresponding to a rejection ratio (RR) of 8.6%. The procedure improved the FoM up to 0.88 corresponding to a RR of 1.9%. We also applied the procedure to the discrimination between beta and gamma rays with a PMT and a phoswich organic detector and to the discrimination between signals collected from neutrons or partial discharges within a fission chamber.