Investigation of the Radiation Sensitivity of the Modified SrCl_{2}–Tl^{+} Crystals

Abstract

If the SrCl₂–Tl⁺ crystals get irradiated with ionizing radiation at a temperature of 80–150 K, the low-temperature color centers appear in them, having surplus electric charge relative to the lattice as a result of capturing electrons and holes by the impurity–vacancy dipoles. If the crystal is irradiated at temperatures above 150 K, when the anionic vacancies can migrate, the high-temperature color centers emerge, which are electrically neutral relative to the lattice. Hence, the coloration of crystal is more effective at high temperatures. However, if the crystal irradiated at high temperatures is cooled down to 80 K, then discolored and re-irradiated with ionizing radiation, both types of color centers are effectively generated in it. Namely, SrCl₂–Tl⁺ crystals have "radiation memory" and, as a result of such modifications, the effectiveness of crystal coloration at low temperatures increases several times. The parameters of radiation sensitivity of the SrCl₂–Tl⁺ crystals were calculated in a one-dimensional model.  The limit concentrations of  the  color  centers as  a function of  the  concentration  of  the Tl⁺-impurity in the crystal were defined. The calculation results are in good agreement with the experimental data, which confirms the validity of using such a one-dimensional model for predicting the radiation properties of real crystals and searching for ways to increase the effectiveness of crystal coloration.