Radiation-induced vacancy aggregation modes and radiation changes in optical and scintillation properties of insulator crystals

The mechanism of radiation changes involves both the formation of vacancy clusters (pores) from photoproduced vacancies and the optical manifestations of pores. The growth of pores is controlled by dislocations (serving as sinks for interstitials generated simultaneously with vacancies). Depending on dislocation density, the total surface of growing pores can vary with radiation dose in quite different ways. This permits one to control crystal properties via a chosen regime of irradiation. Optically, radiation-produced pores manifest themselves as follows: 1) in excitonic absorption, which strongly exceeds the absorption of usual color centers of the same concentration and can be used for estimating the concentration of pores and 2) via trapping excitons inside the exciton band, thus enhancing intrinsic luminescence and diminishing the luminescence of the dope impurity. This paper presents a joint review of the above aspects of the vacancy cluster physics which were developed separately in recent publications of the authors.