Scintillating and particle discrimination properties of selected crystals for low-temperature bolometers: from LiF to BGO

Selected crystals have been investigated at 20 mK for their properties of scintillation produced under irradiation. A scintillation signal is found in preliminary studies of YAP:Ce, GSO:Ce, CaF2:Eu and Al2O3:Ti crystals thanks to high sensitivity light detectors. The full mixed “light-and-heat” bolometric technique has been applied to further characterize materials already employed in rare event researches: CaWO4, BGO, undoped Al2O3 (sapphire). All these crystals show powerful discrimination properties for α/γ or nuclear recoil/γ detection, with a special mention to undoped Al2O3, hitherto untested, which revealed an unexpected strong light emission. A weaker light signal has been found on LiF and TeO2 bolometers too, sufficient to separate alpha from gamma events in these crystals.