Low Temperature Scintillation in ZnSe Crystals

The search for new materials which could be used as scintillating bolometers is a subject of great interest in view of next-generation experiments dedicated to the study of neutrinoless double beta decay (DBD). Preliminary measurements performed on ZnSe bolometric and scintillation characteristics gave very promising results for what concerns the amplitude of the scintillation signal and the capacity to discriminate between a and particles. The current work studies the possibility to develop a scintillating ZnSe crystal adapted for the use as hybrid (thermal and scintillation) detector operating at very low temperatures (< 20 Mk), able to discriminate between a and induced events. The results of optical transmission, X-ray excited steady-state luminescence and thermo-luminescence measurements performed on ZnSe crystals produced in different conditions are presented. Based on these measurements, the scintillation properties of undoped ZnSe crystals are carefully described. The correlation between these measurements and bolometric/scintillation tests is used in order to fix the production conditions of ZnSe crystals which best guarantee scintillation efficiency at very low temperatures for possible use in a DBD experiment.