Effect of gamma irradiation on undoped and uranium doped calcium fluoride crystals

Color centers in undoped and U3+-doped CaF2 crystals induced by γ-irradiation with different doses were studied by differential absorption and Raman spectra. Multiple color centers and conversion among them were caused in undoped CaF2 with the creation of radiation defects. In U3+:CaF2 crystal, trivalent uranium was demonstrated to act as hole trap in the process of γ-irradiation, which was ionized to tetravalent. This process was accompanied by the formation of F2+ centers, but without additional background absorption due to radiation defects.