GROWTH OF BAF2 CRYSTALS BY THE HEAT EXCHANGER METHOD (HEM) WITH ENHANCED FAST COMPONENT FOR SCINTILLATOR APPLICATIONS

THE FAST COMPONENT IN BAF2 IS DUE TO EMISSION AT 220 NM WAVELENGTH; IT WAS DISCOCERED IN 1983. EVEN THOUGH THE SLOW COMPONENT HAS BEEN KNOWN FOR A LONG TIME, THE FAST COMPONENT WAS NOT OBSERVED UNTIL RECENTLY AS IT IS QUENCHED BECAUSE OF SELF-ABSORPTION BY IMPURITIES. THE PRESENT PROPOSAL IS TO ADAPT THE HEAT EXCHANGER METHOD (HEM) FOR THE GROWTH OF BAF2 CRYSTALS. IT IS INTENDED TO GROW 5 CM DIAMETER, 4 CM HIGH CRYSTALS DURING THE PROPOSED SIX-MONTH PERIOD. CRYSTAL GROWTH EXPERIMENTS WILL BE TAILORED TO EVALUATE THE EFFECT OF IMPURITIES (SUCH AS OXIDE PHASE, HYDROXYL IONS AND SECONDARY PHASES), CRYSTAL QUALITY, SIZE AND CRYSTAL GROWTH PARAMETERS ON THE SCINTILLATION PROPERTIES OF BAF2. IN ALL EXPERIMENTS NO SCAVENGERS SUCH AS PBF2 WILL BE USED. THE CRYSTALS GROWN WILL BE CHARACTERIZED AT BROOKHAVEN NATIONAL LABORATORY FOR SCINTILLATION PROPERTIES. AT THE END OF THE PROPOSED SIX-MONTH PROGRAM, TECHNOLOGY WILL BE IN PLACE TO GROW BAF2 CRYSTALS IN WHICH THE FAST COMPONENT IS OPTIMIZED SO THAT THE CRYSTALS CAN BE USED IN FAST TIMING SCINTILLATION APPLICATIONS.