RADIATION-DAMAGE IN BAF2 CRYSTALS

The effects of radiation damage and recovery have been studied in BaF2 crystals exposed to Co-60 radiation. The change in optical transmission and scintillation light output have been measured as a function of dose up to 4.7 x 10(6) rad. Although some crystals exhibit a small change in transmission, a greater change in scintillation light output is observed. Several 25 cm long crystals which have been irradiated show large changes in both transmission and light output. Recovery from radiation damage has been studied as a function of time and exposure to UV light. A long lived radiation induced phosphorescence has been observed in all irradiated samples which is distinct from the standard fast and slow scintillation emissions. The emission spectrum of the phosphorescence has been measured and shows a peak at approximately 330 nm, near the region of the slow scintillation component. Results are given on the dependence of the decay time of the phosphorescence with dose.