科研之友
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摘要
At the High-Throughput Discovery of Scintillator Materials Facility at Lawrence Berkeley National Laboratory, scintillators are synthesized by solid-state reaction or melt mixing, forming crystalline powders. These powders are formed in various granularity and the crystal grain size affects the apparent luminosity of the scintillator. To accurately predict a "full-size" scintillator's crystal luminosity, the crystal luminosity as a function of crystal granularity size has to be known. In this study, we examine Bi4Ge3O12 (BGO), Lu2SiO5:Ce3+ (LSO), YAlO3:Ce3+ (YAP:Ce), and CsBa2I5:Eu2+ (CBI) luminosities as a function of crystalline grain size. The highest luminosities were measured for 600- to 1000-mu m crystal grain sizes for BGO and LSO, for 310- to 600-mu m crystal grain sizes for CBI, and for crystal grains larger than 165 gm for YAP:Ce. Crystal grains that were larger than 1 mm had a lower packing fraction, and smaller grains were affected by internal scattering. We measured a 34% decrease in luminosity for BGO when decreasing from the 600- to 1000-mu m crystal grain size range down to the 20- to 36-mu m range. The corresponding luminosity decrease for LSO was 44% for the same grain size decrease. YAP:Cc exhibited a luminosity decrease of 47% when the grain size decreased from the 165- to 310-mu m crystal grains to the 20- to 36-mu m range, and CBI exhibited a luminosity decrease of 98% when the grain size decreased from the 310- to 600-mu m crystal grain range to the 36- to 50-mu m range. We were able to very accurately estimate full-size crystal luminosities from crystalline grains that are larger than 90 mu m.
