Annealing effects and radiation damage mechanisms of PbWO4 single crystals

The annealing treatments of a PbWO4 crystal sample have been sequentially carried out in air from 640 to 1040 degrees C. After annealing at each temperature, the optical absorption spectra of the crystal have been recorded pre and post UV irradiation exposure. The experimental results show that annealing PbWO4 crystals at a temperature above 740 degrees C in air can effectively wash out the intrinsic color centers causing a 350 nm optical absorption band and improve the radiation hardness of PbWO4 crystals. In addition, during the radiation procedure, the conversions of the 350 nm intrinsic color centers to the 410 nm temporary color centers are evidenced in the experiments. Based on the earlier results, the annealing effects and the radiation damage mechanisms of PbWO4 crystals are discussed. (C) 1999 American Institute of Physics. [S0021-8979(99)00719-7].