On-line measurement of gamma radiation-induced absorption in A3+-codoped PbWO4: Mo crystals

The radiation hardness of the set of seven samples of Mo-doped PbWO4 crystals (from 0 up to 10,000 ppm) and further codoped by Y, La, Nb, is investigated. With increasing Mo concentration above 1000 ppm radiation hardness increases. Codoping by Y, La can still decrease radiation-induced absorption about several tens percent at least, while influence of Nb is not clear. Induced absorption increases with the dose rate, for dose rates higher than 0.35 Gy/min it achieves saturation level. As it is planned to use PbWO4 scintillating crystals at lower temperature in ALICE experiment in CERN, some measurements were performed at temperature -15 deg. C too. Induced absorption coefficient at low temperature is 2-4 times higher with respect to room temperature and kinetic of recovery processes gets slower