Proton, neutron and γ Pulse Shape Discrimination by CLYC Scintillator

[Background]: Cs2LiYCl6:Ce3+(CLYC) is a promising inorganic scintillator with excellent neutron/gamma pulse shape discrimination capability.  [Purpose]: This study aims to investigate the response characteristics of Cs₂LiYCl₆:Ce³⁺ (CLYC) crystals to 21 MeV protons and their pulse shape discrimination (PSD) capability for protons, neutrons, and gamma rays.  [Methods]: Digital waveforms generated by proton irradiation from a tandem accelerator, alongside neutrons from an Am-Be source and gamma rays from ¹³⁷Cs and ⁶⁰Co sources, were acquired. Using the charge comparison method with optimized integration time windows, effective discrimination was achieved between proton and neutron events (Figure of Merit, FOM = 1.86), between proton and gamma events (FOM = 1.0), and in a mixed field of protons, neutrons, and gamma rays (FOM = 2.0 for neutron/gamma, 1.54 for proton/neutron, and 1.45 for proton/gamma).  [Results]: The results indicate that the scintillation pulse shape induced by protons in CLYC crystals comprises four decay components: core-to-valence luminescence (CVL, ~3.8 ns), Ce³⁺-related emission, Vk center-related emission, and self-trapped exciton (STE) emission.  [Conclusions]: This work confirms the capability of CLYC crystals for simultaneous detection and discrimination of protons, neutrons, and gamma rays, supporting their potential application in complex radiation environments such as space radiation detection.