Afterglow of heavily irradiated sapphire

A previous paper reported an "anomalous" fading of optical absorption in corundum previously irradiated by reactor neutrons after its exposure to X-rays. It was found that the optical density (OD) followed a linear decay on an OD vs. Log (time) plot. We have since obtained such a dependence for the afterglow intensity with time for heavily irradiated sapphire. It is assumed that in both cases electrons annihilation occurs on hole centers. As a hole partner there may be the hole center described by us previously, which included an interstitial oxygen. The electron partner is a deep electron trap similar to that occurring under irradiation of reduced crystal.