Investigation of CeBr3−xIx scintillators.

• Mixed scintillator CeBr 3−x I x was investigated. • X-ray diffraction was used to determine the structure both phases that formed. • Five singled crystals were grown via the vertical Bridgman technique. • A light yield of >80,000 ph/MeV was measured for the grown crystal CeBr 2 I. CeBr 3 is an intrinsic scintillator that has promising performance capabilities such as 60,000 ph/MeV and ~4% energy resolution at 662 keV. It has been shown that halide mixing can improve the light yield of single halide scintillators. In this work we attempted to improve on CeBr 3 by creating a mixed halide composition CeBr 3−x I x. Analysis of melt-freeze samples revealed that the light yield of CeI 3 rapidly increases as bromine is substituted. Thirteen mm diameter crystals were grown using the vertical Bridgman technique, with x values between 0.03 and 1. The CeBr 2.5 I 0.5 crystal segregated into two sections, colorless and green, while the CeBr 2 I crystal was entirely green. X-ray diffraction analysis was used to identify the two phases. Decay time increased as iodine concentration increased. All colorless phase crystals reached <4.5% energy resolution at 662 keV and >65,000 ph/MeV, with the CeBr 2.94 I 0.06 crystal achieving 3.9% energy resolution at 662 keV. The green phase crystals both reached light yields of 78,000 ph/MeV, the highest ever recorded for a CeI 3 phase crystal. [ABSTRACT FROM AUTHOR]