Qualification of a compact neutron detector based on SiPM

Abstract

A: 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 × 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.

Impact of the Detected Scintillation Light Intensity on Neutron-Gamma Discrimination

“…As of the characterisation reported in [3] and the comparative analysis performed in [18], neutron-gamma discrimination was based on a Pulse Shape Discrimination (PSD) variable corresponding to the energy deposited in the tail of the signal, normalised to the pulse height:…”

“…S ilicon Photomultipliers (SiPMs hereafter) are compact solid state light detectors with single photon sensitivity, photon counting capability, low bias voltage and low power consumption. In the last decade, SiPMs have been used in a variety of fields, such as particle and nuclear physics, medical imaging and homeland security [1]- [3]. It has been shown that SiPMs, coupled to specifically engineered scintillators with sensitivity to both fast and slow neutrons, represent a viable solution for the discrimination of light pulses originated by gamma rays against neutrons [4].…”