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In this work the Bridgman crystal growth and scintillation properties of both undoped and Tl-doped Cs 3 Cu 2 I 5 are presented. This material is very attractive for gamma and X-ray detection applications, with a density of 4.53 g/cm3 and effective atomic number of 51.9. Undoped Cs 3 Cu 2 I 5 had a light yield of 41,500 photons/MeV, with an energy resolution of 4.4% at 662 keV. Thallium doping at 0.5 mol % resulted in a much-improved scintillation response, in which light yield increased to 98,200 photons/MeV and energy resolution reduced to 3.3% at 662 keV. The X-ray excited emission is centered at 442 nm for the undoped and 500 nm for the Tl-doped crystals. The undoped emission is broad, typical of excitonic emission, while thallium doping results in an even broader band with features of both the undoped and thallium defect-mediated emissions. • Transparent single crystals of undoped Cs 3 Cu 2 I 5 and Cs 3 Cu 2 I 5 (Tl) were grown via the Bridgman technique. • Phase purity was established via powder XRD analysis. • Undoped Cs 3 Cu 2 I 5 has 41,500 photons/MeV and 4.4% energy resolution at 662 keV. • Tl doping at 0.5 mol% improves light yield to 98,200 photons/MeV and energy resolution to 3.3%. [ABSTRACT FROM AUTHOR]

We investigate the multi-ampoule growth at 25 mm diameter of ternary iodide single crystal scintillator KCaI 3 :Eu using the randomly oriented self-seeded Bridgman method. We compare scintillation performance between cubic inch scale crystals containing small variations of low nominal europium concentrations previously shown to balance light yield with self-absorption in the host crystal. Growth conditions were optimized in the developmental furnace and four 2 in 3 KCaI 3 :Eu crystals were grown simultaneously producing a total of six 25 mm × 25 mm cylinders. Small variations in activator concentration did not result in significant performance differences among the six measured crystals. A range of energy resolutions of 3.5–4.7% at 662 keV was achieved, surpassing that of NaI:Tl crystals commonly used in spectroscopic detection applications. The function and basic design of the multi-ampoule furnace as well as the process of growing single crystals of KCaI 3 is included here. [ABSTRACT FROM AUTHOR]