Characterizations of a New Tl-based Elpasolite Scintillator: Tl2LiScCl6

Abstract

A new Tl2LiScCl6 (TLSC) single crystal was grown by using the two-zone vertical Bridgman method. The TLSC belongs to the cubic chloro-elpasolite crystal family. Under X-ray excitation at room temperature, an emission spectrum from 300 to 550 nm was obtained, with the maximum emission being at 385 nm. The scintillation properties, such as the energy resolution, light yield and decay time of the TLSC crystal, were measured at room temperature by using a 137Cs γ-ray source. The energy resolution at the 662 keV photopeak was found to be 8.3% (full width at half maximum). Using the LYSO light yield as a reference, we obtained the light yield of the TLSC crystal as 26000 ± 2600 ph/MeV under excitation by 662 keV γ-rays. The developed crystal shows a single exponential decay time of 1.147 µs under 662 keV γ-ray excitation from a 137Cs source. Due to the high effective Z-number (67) and density of the TLSC crystal, it can be used for efficient detection of X- and γ-rays in various applications. It also has a potential to be used for detection of thermal neutrons via the 6Li(n, α) reaction. Further improvements in the scintillation properties are expected with rare-earth doping in this compound, which is the subject of our future work.