Abstract-We describe the design and operation of a highthroughput facility for synthesizing thousands of inorganic crystalline samples per year and evaluating them as potential scintillation detector materials. This facility includes a robotic dispenser, arrays of automated furnaces, a dual-beam X-ray generator for diffractometery and luminescence spectroscopy, a pulsed X-ray generator for time response measurements, computer-controlled sample changers, an optical spectrometer, and a network-accessible database management system that captures all synthesis and measurement data.

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Trivalent bismuth luminescence is reported in three Sillen bismuth oxyhalide phases, SrBiO 2 Cl, BaBiO 2 Cl, and BaBiO 2 Br. These compounds exhibit Bi 6s6p → 6s 2 emission under UV and X-ray radiation. At room temperature, BaBiO 2 Cl shows the most intense light emission, with spectral and decay properties similar to those found in Bi 4 Ge 3 O 12 (BGO). At low temperatures, each phase show an increase in the photoluminescence intensities and a narrowing of the emission peaks. In contrast to the temperature dependence of BGO, X-ray excited luminescence intensities of all three phases remain relatively constant throughout the temperature range 10 -295 K. This result indicates that the Sillen phases undergo less thermal quenching than BGO. The low temperature and room temperature radio-luminescence decay times were determined from pulsed xray measurements. At room temperature, SrBiO 2 Cl exhibits faster decays than BGO, while, BaBiO 2 Cl and BaBiO 2 Br have decay times similar to BGO.

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We report the scintillation properties of the undoped and cerium-doped variations of LiGdCl 4 and NaGdCl 4 .Powder samples of these materials exhibit significant scintillation under X-rays. The samples were synthesized by solid-state methods from a 1:1 molar ratio of lithium or sodium chloride and gadolinium trichloride. Cerium trichloride was used as the dopant. The physical, optical, and scintillation properties of these materials were analyzed by powder X-ray diffraction, photoluminescence, X-ray excited luminescence, and pulsed X-ray luminosity measurements. Increases in light yields are observed as the concentration of cerium increases. The highest light yields occurred at 20% cerium doping for both compounds. At larger concentrations neither compound formed, indicating a breakdown of the lattice with the addition of large amounts of cerium cations.At 20% cerium, LiGdCl 4 and NaGdCl 4 display scintillation light 3.6 times and 2.2 times the light yield of the reference material, YAlO 3 :Ce 3+ , respectively. Both emit in the ranges of 340-350 nm and 365-370 nm and display multiexponential decays with cerium-like decay components at 33 ns (LiGdCl 4 : Ce) and 26 ns (NaGdCl 4 : Ce).