Crystal growth and spectroscopic performance of large crystalline boules of CsCaI3:Eu scintillator

• Time-lapse video of high temperature melt growth.
• Spectroscopic performance varies with volume.
• Twinning observed in bulk crystals.

The crystal growth of CsCaI3:Eu with improved quality over prior efforts for use in X-ray and gamma-ray detection applications is reported. Boules were grown using the vertical Bridgman technique in quartz ampoules at 15, 22, and 35 mm diameters. CsCaI3:Eu crystals show evidence of a heavily twinned microstructure likely caused by a solid-solid phase transformation of the crystal during the cooling process. Energy resolution (FWHM) in large and small samples taken from crystalline boules varies between 13% and 4.5% for 662 keV gamma rays indicating volumetric non-uniformity. Scintillation decay time is shown to increase with volume. Proportionality of the light yield of CsCaI3:Eu is reported for the first time.