Effect of Co-doping On the Radiation Hardness of ${{\rm Gd}_3}{{\rm Ga}_3}{{\rm Al}_2}{{\rm O}_{12}}$ : Ce Scintillators

Single crystals of Gd₃Ga₃Al₂O₁₂:Ce with Ca, B and Ba codopants were successfully grown using the Czochralski technique. The samples of each composition were irradiated to 10 kGy and 100 kGy gamma dose to determine the radiation induced absorption. The Ca co-doped crystal was found to have maximum induced absorption, while B and Ba co-doped were found to be more radiation hard. The reduction in transmission could be partially restored at room temperature without any annealing treatment of the crystals. The additional absorption was also measured after annealing the crystals in reducing environment and compared with the radiation induced absorption. Thermoluminescence measurements were carried out to explain the defect structure and recovery of the transmission reduction at room temperature.