Changes in luminescence of Ce : YAG crystals under ionizing radiation treatment

Radiation induced changes in the luminescence spectrum under influence of U V light, gamma-rays, electrons and protons for several concentrations of Ce 3+ ions as well as Mg2+ ions in yttrium-aluminum garnet crystals were inves tigated. To irradiate with gamma and electron as grown crystals were used w hile for proton irradiations the crystals were thermally annealed. For smal l concentrations of cerium ions (approximate to 0.01 at.%) an increase in t he luminescence (about 100%) was observed after gamma irradiation with a do se of 10(5) Gy. This increase was due to the growth in Ce3+ ions concentrat ion after gamma-irradiation (approximate to 50%), due to the Ce4+ --> Ce3recharging reaction. For highly doped Ce:YAG crystals (0.1 at%, 0.2 at.%) a lso an increase, but much smaller (4%), for the Mg codoped crystals (0.1 at .%) was observed. After 1 MeV electron irradiation in the over-threshold ty pe interaction a decrease in luminescence is observed due to the domination of the Ce3+ --> Ce4+ ionization process. In the case of the proton irradia tion, for small fluencies (approximate to 10(13) particles/cm(2)) an increa se in luminescence is observed due to the domination of the recharging proc esses of Ce4+ ions. For larger fluencies (>10(14) particles/cm(2)) a decrea se takes place one to a high level or radiation defects.