Comparison of the pulse shape discrimination performance of plastic scintillators coupled to a SiPM

We report on the pulse shape discrimination (PSD) performance of plastic scintillators manufactured by Eljen Corporation and Amcrys. In this study we investigate the fast neutron and gamma performance of the plastic scintillators when coupled to the SensL J-series silicon photomultiplier (SiPM) and read out with fast waveform digitisers with an ADC resolution of 14-bits and a sample rate of 500 MS/s. The investigation observes a significant PSD performance increase for the SensL J-series SiPM in comparison to the previous C-series, and also for the latest variants of plastic scintillator from both suppliers. Analysis was performed using a Synchronous Charge Integration Pulse Shape Discrimination (PSD) algorithm which was applied to data acquired from a mixed fast neutron/gamma radiation field from an AmBe neutron source. The collected pulses were processed offline with the energy and PSD parameters calculated. The quality of the PSD performance was characterised by a common figure of merit (FoM). The best n- separation was found by the newer Eljen EJ-276 scintillator with a FoM value of 3.03 ± 0.03 at an energy of 1.5 MeV gamma equivalent. The Amcrys UPS-113NG material achieved a FoM value of 2.60 ± 0.04.