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7Li enriched Cs2LiYCl6:Ce3+ (CLYC) is a promising inorganic scintillator for real-time γ-ray and fast neutron spectrometry. The neutron/γ-ray discrimination is usually accomplished exploiting the different quenching effects of high Linear Energy Transfer (LET) particles on different scintillation mechanisms, usually by means of the time analysis of the pulse shape. In principle, the emission wavelength information could be used to address the same task. However, a systematic study of the correlations between the CLYC decay time, its radio-luminescence spectrum and the LET of the impinging particle has not yet been performed. We therefore investigated the CLYC scintillation process under neutron and γ-ray irradiation, correlating the time response to the scintillation wavelength spectrum using a 1–inch right cylinder>99% 7Li enriched CLYC. We found that the relative intensity of the Core to Valence Luminescence (CVL) is almost constant with photons in the energy range 20–660 keV, i.e. 0.5–5 keV/μm LET, and is only partially quenched by neutrons. Instead, the direct electron-hole capture scintillation mechanism is completely cut under neutron irradiation. The luminescence in between the deep-Ultraviolet and the Near Ultraviolet region (250–350 nm) might be attributed to both the CVL and the host luminescence, also in thick highly Ce3+-doped crystals.

A 1-inch stilbene and EJ-276 (plastic) organic scintillators were characterized in view of their use in a portable survey meter for fast neutron detection and dose rate measurements in radiation protection. They were coupled with a large area Silicon Photomultiplier (SiPM) array and characterized in terms of neutron/ γ –ray (n/ γ ) discrimination capability, count rate linearity, count rate saturation effects, temperature stability and neutron detection efficiency. A Pile-Up Rejection (PUR) algorithm was developed and tested to increase their count rate linearity with increasing dose rate. Results show that the stilbene exhibits better performance compared to the plastic in terms of: Pulse Shape Discrimination (PSD) with a Figure Of Merit (FOM) of 1.5 vs. 1.1, energy resolution (15% vs 20% at 662 keV) and fast neutron efficiency (12% vs. 9% with an AmBe source). For both scintillators, the dose rate response is linear up to 1 mSv/h with a 137Cs γ -ray source. With a neutron source , the response is linear, and the FOM is almost constant for dose rates up to 1.5 mSv/h. The PUR reduces the false neutron events by one order of magnitude when the detectors are irradiated with a γ -ray source up to 10 mSv/h, and it correctly works when irradiated with an AmBe source at 1.5 mSv/h together with a 137Cs source up to 60 μ Sv/h. The proposed PUR algorithm is promising but needs to be tested with a higher intensity mixed n/ γ field. The temperature stability of both detectors was also studied in the temperature range from −10 °C to ＋40 °C. The light yield increases by around 25% for both detectors when reducing the temperature. The variation of the neutron count rate is around 10% in the same temperature range. This work provides a complete overview of the performance of these detectors and a coherent comparison between the two types of scintillators with the same experimental setup.