A study on the radiation hardness of lead tungstate crystals

This report presents recent progress of a study on the radiation damage in lead tungstate (PbWO/sub 4/) crystals. The dose rate dependence of radiation damage in PbWO/sub 4/ has been observed, confirming our early prediction based upon a kinetic model of color centers. An optimization of the oxygen compensation through post-growth thermal annealing, carried out in Shanghai Institute of Ceramics, has led to PbWO/sub 4/ crystals with significantly improved radiation hardness. A comparison between front versus uniform irradiations revealed that the later caused a factor of 2 to 6 times more severe damage. A measurement of a preliminary batch of lanthanum doped PbWO/sub 4/ crystals indicates that the La doping seems not a determine factor for PbWO/sub 4/ radiation hardness improvement. Finally, a TEM/EDS analysis confirmed our previous conjecture that the radiation damage in PbWO/sub 4/ crystals is caused by oxygen vacancies.