Approaching the Theoretical Light Yield Limit in CsI (Tl) Scintillator Single Crystals by a Low-Temperature Solution Method

A nonvacuum solution-based growth process featuring an inverse temperature crystallization was demonstrated to grow high light yield halide scintillator single crystals. The as-grown Tl-doped cesium iodide, CsI­(Tl), single crystals exhibit high transparency and characteristic Tl-doped photoluminescence and X-ray excited luminescence spectra with a decay time of about 535 ns at 550 nm emission peak. The CsI­(Tl) scintillator with a low Tl doping concentration of 146.7 ppm grown by the solvent-based growth method exhibits a high light yield of 119 000 ± 6000 photons/MeV, which is about 1.3 times higher than those grown by the conventional melting method with a higher Tl concentration. This simple and convenient process may present a promising low-cost method for the mass production development of halide scintillator single crystals.