Large-Diameter Bulk Crystal Growth and Scintillation Characterization of Thallium-Based Ternary Halide Crystals for Detection and Imaging

Scintillators are important for a wide range of applications in detection and imaging. In this paper, the growth and performance results of advanced large-diameter thallium-based ternary halide crystals are presented. Intrinsic crystals of TlMgCl3, TlCaCl3, and other small-diameter TlCaBr3, and TlCa(Cl,Br)3, as well as europium-doped TlCa2Br5, TlCa(Cl,Br)3, and TlSr2I5 are melt-grown by the Bridgman method. These compounds have a high effective atomic number (Zeff) and physical densities due to thallium. The best crystal quality and energy resolution (FWHM) at 662 keV are observed for TlMgCl3, TlCaCl3, and TlSr2I5:Eu at 3.8%, 4.6%, and 3.5%, respectively. The primary decay constants for these compounds are in the range of 0.45 to 0.63 μs. These ternary Tl-halide compounds have proportional or linear response (±0.05%) to γ-rays above 40 keV.