Effects of structure microdefects on scintillation and photostimulated properties of CdWO4 crystals

摘要

Abstract: CdWO$-4$/(CWO) scintillator single crystals find broad applications as detectors of ionizing radiation in tomographic and introscopic devices. Scintillation characteristics of the crystals are strongly dependent upon growth conditions. In this paper the nature of the defects is studied, related to deviations from stoichiometry and presence of admixtures, for the crystals grow by the Chochralski method. Negative effects of admixtures (Fe, Cu, Bi, Ga ions) on the light yield and afterglow in CWO crystals were established. Photosensitivity of CWO crystals under UV-radiation was noted in the region of the fundamental absorption edge, causing the induced absorption ($alpha up to 1.5 cm$+$MIN@1$/) and a decrease of the light yield (to 30%). The studies have shown that the induced absorption depends upon both admixtures and non- stoichiometry. Basing on the results, preparation conditions were optimized for large-sized (55 $MUL 250 mm) CWO crystals, allowing to obtain scintillation characteristics meeting the requirements for their use in radiation detectors for tomography and introscopy.!4