EFFECT OF ANNEALING ON ABSORPTION AND ROENTGENOLUMINESCENCE OF PbWO_4 CRYSTALS

摘要

The effect of annealing in vacuum, argon, and air on the absorption and roentgenoluminescence spectra of PbWO_4 crystals was studied. Annealing in an oxygen-deficient atmosphere was found to bleach initially yellow crystals, suppressing the absorption in the region from 375 to 500 nm;to reduce the intensity of the roentgenoluminescence band; and to shift it to shorter wavelengths. These effects are most pronounced at annealing temperatures from 750 to 800℃.Subsequent annealing in air restores the original properties of PbWO_4.The formation and dissociation of color and green-emission centers were correlated with the oxygen exchange between the environment and crystal during annealing in different atmospheres.