Qualification of a compact neutron detector based on SiPM

Silicon Photomultipliers (SiPM) are photon sensors featuring high detection efficiency, single photon sensitivity and extended dynamic range; they represent a valuable solution for compact and lightweight hand-held instruments ideal for border control against the illicit trafficking of radioactive material or environmental measurements. This paper reports the results obtained with a standalone compact and modular system (I-spector) customized to detect fast neutrons with gamma discrimination capability. The system consists of 4 SiPM ($6\times 6$ mm${}^2$ each) coupled to a fast neutron sensitive scintillating material (EJ-276). It includes an HV bias generator, an on-board digitizer and a microcontroller to perform real-time pulse shape analysis, ethernet and LORA connectivity. The measurements performed to define the specifications and to steer the design will be discussed, together with the results achieved by the prototype in response to a ${}^{252}$Cf source. The system has been shown to be linear up to 6 MeV achieving a neutron-gamma discrimination with a Figure of Merit (FoM) of 2.52 ± 0.09 in the energy window of 1–1.5 MeV together with a FoM larger than 1.27 down to 200–300 keV