Photostimulated trap filling in Lu2SiO5:Ce3+

Upon exposing Lu2SiO5:Ce3+ scintillators to daylight, the material shows undesired intense afterglow lasting for several hours at room temperature. This effect is studied by means of illuminating Lu2SiO5:Ce3+ with visible and ultraviolet light. Conditions for trap filling and the relation with photoconductivity phenomena and Ce3+ luminescence quenching will be discussed. Autoionization of so-called Ce2 centres following the excitation to the lowest 5d level seems to play an important role in the mechanism.