Impact of Lu/Gd ratio and activator concentration on structure and scintillation properties of LGSO:Ce crystals

We have studied the dependence of structural and scintillation characteristics of Lu2xGd2−2xSiO5:Ce (LGSO:Ce) crystals on cation composition. LGSO:Ce crystals at x=0–1 have been obtained by the Czochralski method. We report here a strong correlation between ionic radii of trivalent cations and their distribution between non-equivalent sites in lattice. By choosing the optimal Lu/Gd ratio and Ce concentration we were able to obtain the light output by∼70%, as compared to LSO:Ce crystals, and energy resolution ∼7 at% 662 KeV (137Cs); the afterglow level was decreased by 1–3 orders of magnitude as compared to LSO:Ce. We also discuss the possible mechanisms of control on scintillation characteristics of mixed orthosilicates.