Photoluminescence and scintillation of TlBr crystals at low temperatures

Abstract

The photoluminescence and X-ray-induced radioluminescence properties of TlBr crystals were analyzed. We compared the samples cut from two parts of the crystal that are empirically known to be appropriate and inappropriate for semiconductor detectors. In the X-ray-induced radioluminescence spectra, two bands were observed at 490 and 650 nm for both the samples. We observed an additional band at 560 nm only for the inappropriate part of the crystal. We observed an emission band at 520 nm in the photoluminescence spectra of both the samples and attributed this to some defects near the surface on which photoexcitation occurs. Interestingly, an emission band at 560 nm appeared after thermal cycle from room temperature to 5 K and back to room temperature. Assuming that the thermal cycle introduced some distortions in the sample, the emission band at 560 nm could be related to lattice defects, such as dislocation, that are relevant to distortion.