Eu2+-doped Ba2CsI5, a new high-performance scintillator

The crystal growth and scintillation properties of Ba2CsI5:Eu2+ are reported. Crystals were produced by the vertical Bridgman technique in a sealed quartz ampoule. Ba2CsI5:Eu2+ presents excellent scintillation properties. An estimated light yield of 97,000±5,000 photons per MeV (ph/MeV) of absorbed gamma-ray energy was measured. An energy resolution (FWHM over peak position) of 3.8±0.3% was observed for the 662 keV full absorption peak. Pulsed X-ray luminescence measurements show a relatively complex time response with four exponential decay components of 48,383, 1500 and 9900 ns with a contribution to the total light output of 1%, 26%, 68% and 25%, respectively. Under X-ray and UV excitation, the emission corresponds to a broadband centered at 2.85 eV. First principles calculations show strong localization of the excited state on the Eu site. Ba2CsI5:Eu2+ has a density of about 5 g/cm3. These first reported scintillation properties make Ba2CsI5:Eu2+ a very high-performance scintillator.