Qualification and performance of a neutron detector system with enhanced gamma discrimination, based on Silicon Photomultiplier arrays coupled to an EJ-299-34 scintillator

Silicon Photomultipliers (SiPM) are a new class of photon sensors featuring high detection efficiency, single photon sensitivity and extended dynamic range; they represent a valuable solution for compact, lightweight hand-held instruments, possibly battery operated. This paper reports the studies performed with an array of 16 SiPM coupled to a novel plastic scintillator sensitive to fast neutrons with gamma discrimination, a proof-of-concept towards the development of instruments for border control against the illicit trafficking of radioactive material. The array of SiPM provides 16 individual outputs but, in this application, a single signal proportional to the total amount of light seen by the sensor is required. Two different Front-End EIectronics (FEE) circuits to sum the analogue signals have been considered and compared. The comparison has been based on the impact of the FEE on the neutron-gamma discrimination capability, based on on Pulse Shape Discrimination (PSD) algorithms. The optimal configuration has been shown to provide a Figure of Merit (FoM) of 2.56±0.0I in the energy window of 1 - I.5~mathrm Mmathrm emathrm V, confirming the state-of-the-art performance of this solution.