A large neutron/gamma detector based on the EJ-276G plastic scintillator read out with multiple SiPM arrays

This work presents the characterization of a large EJ-276G scintillator (3” diam. x 3” thick.), focusing on its energy resolution, neutron/gamma-ray discrimination performance, proton light output response, and intrinsic neutron efficiency. The study evaluates the performance of the detector when coupled to both a conventional PMT and SiPM arrays, understanding how the performance is improved with two SiPM arrays compared to a single array. The results show that the two-SiPM configuration outperforms the single-SiPM setup, improving energy resolution by 28% and increasing the FoM by 9%. To enable an absolute comparison of the results, the values were normalized as a function of the number of photoelectrons generated for each configuration. The proton light output function of the EJ-276G was determined through proton beam irradiation, and its intrinsic neutron efficiency was calculated using Monte Carlo simulations with the Geant4 v10.7 toolkit. The results show that the intrinsic neutron efficiency of the large EJ-276G detector ranges from 34% to 45% for neutron energies between 1 MeV and 5 MeV. These findings demonstrate the potential of this large EJ-276G detector configuration for neutron/gamma-ray discrimination and its suitability for applications requiring high detection efficiency, as well as compact and low-power readout using SiPM arrays.