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In this study we investigate the role of traps on radio- and photo-luminescence properties of terbium doped silica. The investigation is motivated by the promising characteristics of rare-earth doped silica obtained by the sol-gel technique as scintillating material. We focus on those phenomena that can be responsible for problematic properties such as the increase of radio-luminescence sensitivity following repeated irradiations. A set of terbium doped silica with different terbium concentrations (0.03 mo1%, 0.1 mo1% and 10 mo1%) prepared by the sol-gel technique and densified at 1050 °C in oxidizing atmosphere has been considered. The effect of a post-densification rapid thermal treatment on the RL and PL properties has also been investigated. This treatment improved the scintillation characteristics of the samples reducing their RL instability under prolonged irradiation.

Point defects and impurities play a major role in optical properties of scintillators, as they can be at the origin of afterglow emission, which are detrimental for the applications. Spectrally-resolved thermally stimulated luminescence (TSL) is used here to study defects possibly affecting scintillation properties of LaCl3:Ce and LaBr3:Ce samples grown by Saint-Gobain Crystals & Detectors. In the case of LaCl 3:Ce, after X-ray irradiation two major glow peaks with complex structures are detected at 23 K and 63 K (when measured at a heating rate of 0.1 K/s). A more composite structure of the TSL pattern of LaBr3:Ce is observed. Possible explanations and implications of these findings are discussed.

Radio-luminescence, time resolved photo-luminescence and Raman spectroscopy measurements were performed on Ce-doped sol-gel silica glasses. Quenching of the 5d-4f Ce3+ emission transition was observed by increasing Ce 3+ concentration above 0.04 mol%, evidenced by a decrease of the emission intensity accompanied by the appearance of a fast component in the photoluminescence time decay. Raman measurements revealed the formation of CeO2 clusters, which can be considered a cause of the observed luminescence quenching.