Influence of variable tungsten valency on optical transmittance and radiation hardness of lead tungstate (PWO) scintillation crystals

摘要

A new approach to interpret the radiation hardness of PbWO_4 (PWO) scintillators is developed by revealing importance of the inclusions of tungsten oxides WO_(3-x) with variable valency. It is demonstrated that the influence of the ionizing radiation on PWO is, in many aspects, similar to the effect of the high-temperature annealing in oxygenless ambient. In both cases, a valency change of the tungsten oxides is initiated and results in induced absorption and, consequently, in crystal coloration. In the PWO crystals doped with L_2O_3 (L = Y,La,Gd), the radiation hardness and the optical properties are mainly affected by inclusions of W_(1-y)L_yO_(3-x) (0