A study on radiation damage in doped BGO crystals

We report on a study of the correlation between radiation damage of bismuth germanate (BGO) scmtillator crystals and trace impunties in the crystal . The light yield and the absorption spectra of doped BGO crystals were measured, both before and after irradiation . While trace concentrations of Cr, Mn, Fe and Pb m BGO were found to lead to substantial radiation damage, traces of Al, Ca, Cu and St were found to have no measurable effect . Traces of Co, Ga, Mg and Ni were found to have an effect intermediate between the above two groups . Three radiation-induced absorption bands were observed in a set of BGO crystal samples . Their energy levels were found to be independent of the trace elements m the BGO. They are at 2.3±0 .1, 3.0±0 .1 and 3.8±0 .1 eV, respectively, above the valence band . A brief discussion of the radiation damage mechanism in BGO is presented.