Nonproportional Response and Energy Resolution of Pure SrI₂ and SrI₂:5%Eu Scintillators

Nonproportional response of the scintillation yield of un-doped SrI2and SrI2:5o/oEu was studied using highly monochromatic synchrotron irradiation ranging from 10.5 to 100 keV. Measurements were performed at 80 K and 295 K for SrI , and at 80 K, 295 K, 450 K, and 600 K for SrI2:5o/oEu. By making a dense data sampling around the iodine K-edge and using the recently developed K-dip spectroscopy method, the K-shell photoelectron response curves were reconstructed down to 500 eV. Proportionalities of X-ray response and K-shell photoelectron response of both crystals reveal temperature dependence. Energy resolution of the X-ray photopeak was analyzed as a function of temperature and deposited energy. Energy resolution improves with better proportionality.