PHOTOSTIMULATED LUMINESCENCE AND THERMOLUMINESCENCE OF LSO SCINTILLATORS

Photostimulated luminescence (PSL) and thermoluminescence (TL) from fi ve Lu2(1-x)Ce2x(SiO4)O (LSO) crystals with different light outputs is reported. Optical irradiation into the Ce3+ absorption bands causes th e appearance of a broad absorption band near 280 nm which is ascribed to Ce4+. In addition, a tail is observed extending beyond 700 nm. Opti cal irradiation into this tail (PSL) or heating of the crystal (TL) re sults in Ce3+ emission. It is shown that both PSL and TL are due to th e same traps. In addition, an anti-correlation is found between the li ght output under gamma-ray irradiation and the trap concentration in t he crystal. The nature of the recombination centers responsible for th e low light output in some crystals is not clear. Annealing experiment s suggest that the traps and the recombination centers may be related to oxygen vacancies.