Gamma-rays induced color centers in Pb2+ doped CaF2 crystals

Pure and PbF2 doped CaF2 crystals were obtained in our crystal research laboratory. The influence of PbF2 concentration on the color centers induced by γ-and x-rays irradiation were studied. Two broad absorption bands with maxima peaked at 410 and 730 nm appear in the optical absorption spectra; the spectra are quite similar in band structure for all samples and for the both radiation. Different bands showed different responses to the irradiation and to the long-term recovery. The most stable color centers are (Fi0) and the dimer P-P (Pb+(1)-Pb2+). These absorption bands remain stable even for trace amount of Pb2+ ions, so CaF2:PbF2 is not a good material for applications in which the new optical absorption bands are undesirable.