Proton damage in (Y,Lu,Gd)₃(Al,Ga)₅O₁₂:Ce mixed garnet scintillators

Scintillators are vital components for nuclear instrumentation and its applications, including plasma diagnostics and imaging. As yields in controlled fusion experiments increase, the radiation tolerance of scintillator candidates for use in instrumentation is of particular importance. High radiation exposure can damage scintillating materials and alter the optical properties. The effects of radiation damage in Ce-doped mixed garnet ceramics over the compositional range (Y,Gd,Lu)₃(Al,Ga)₅O₁₂ are investigated using optical techniques. The samples were exposed to 200 keV protons to an accumulated fluence of 10¹⁶ protons per square centimeter, then characterized using diffuse reflectance spectroscopy (DRS). DRS with visible light can assess the radiation tolerance of opaque poly-crystalline samples, which can be easily sintered from powders and thus offer distinct advantages in characterization compared to single crystals. Qualitative trends in induced absorption are presented as a function of composition, and the ideal cerium dopant concentration for Y₂LuAl₅O₁₂ is determined to be 0.60-0.75 mol. %.