Scintillation properties of a Cs2LiLa(Br6)90%(Cl6)10%:Ce (CLLBC) crystal

Abstract

In investigations of Ce³⁺-doped Cs₂LiLa(Br6)_90%(Cl6)_10% (CLLBC) elpasolite crystals, the crystals show an excellent neutron and gamma (n/γ) radiation response. The results of our studies on the scintillation properties of CLLBC viz. radioluminescence, energy resolution, light yield, decay times, and nonproportionality are discussed. The CLLBC detector can provide energy resolution as good as 4.1% at 662 keV (FWHM), which is better than that of NaI:Tl. Because the crystal contains ⁶Li, CLLBC can also detect thermal neutrons. In the energy spectra, the full energy thermal neutron peak appears near or above 3 MeV gamma equivalent energy. This high-energy signature for the thermal neutron peak means that very effective pulse height discrimination is possible. Unfortunately, because the core-to-valence luminescence observed in other elpasolites that can be exploited for effective pulse shape discrimination (PSD) is not observed in the CLLBC, other strategies for obtaining the PSD of CLLBC are needed. The n/γ discrimination capability of CLLBC detectors may be optimized by tuning the cerium doping content for maximum effect on n/γ pulse shape differences. The value of adding a chlorine component to the nominal CLLB crystal is discussed. Because the crystal contains chlorine, its sensitivity to fast neutrons is better than that of Cs₂LiLaBr₆(CLLB). Further, an array of three of these CLLBC detectors may be able to perform directional detection in both the neutron and gamma channels simultaneously.