Rapid cooling of divalent cation doped alkali halide crystals

The importance of rapid cooling from high temperatures to retain a random dispersion of [M++V−] divalent cation impurity–vacancy pairs is demonstrated. For fully efficient quenches very thin crystals with relatively small broad face areas should be used. For crystals such as LiF TLD100 containing about 170 ppm Mg++ it is also necessary to quench into a liquid such as acetone. In many clustering studies in the past using large crystals, substantial clustering must have taken place during the quench.