Annealing effects and radiation damage mechanisms of PbWO4 single crystals

The annealing treatments of a PbWO4 crystal sample have been sequentially c arried out in air from 640 to 1040 degrees C. After annealing at each tempe rature, the optical absorption spectra of the crystal have been recorded pr e and post UV irradiation exposure. The experimental results show that anne aling PbWO4 crystals at a temperature above 740 degrees C in air can effect ively wash out the intrinsic color centers causing a 350 nm optical absorpt ion band and improve the radiation hardness of PbWO4 crystals. In addition, during the radiation procedure, the conversions of the 350 nm intrinsic co lor centers to the 410 nm temporary color centers are evidenced in the expe riments. Based on the earlier results, the annealing effects and the radiat ion damage mechanisms of PbWO4 crystals are discussed. (C) 1999 American In stitute of Physics. [S0021-8979(99)00719-7].