Systematic Investigation of Defect-Mediated Photoluminescence Through Radiation-Induced Displacement Damage

Abstract

Phosphors have been used for radiation detection before, but only for non-ionizing radiation. In fact, many phosphors are designed to be radiation-resistant so they can be used long-term and in harsh environments unaffected. Furthermore, many of the phosphors used in radiation environments are subjected to ionizing radiation. Our goal, however, is to find a material that changes permanently by non-ionizing radiation and that can be used as a record for radiation exposure. Ideally the material will be sensitive to a wide range of fluences as well as selective to different types and doses of radiation exposure. To determine if radiation can damage phosphors, we systematically exposed several materials to x-rays, alpha particles, protons, and neutrons. We expect radiation to cause displacement dam- age and change the structure of the material. Since phosphor luminescence intensity and lifetime are mainly governed by the arrangement of luminescent centers in the host lattice and the local crystal environment of each luminescence center, the optical properties can be used to detect these structural changes. The results of these experiments provide insight into the possible mechanisms of damage and instruct how to adjust our approach to developing a material with the desired interactions with radiation.