Ion-induced damage in alkali halide crystals

Abstract

An investigation has been made of radiation damage in alkali halide crystals induced by heavy bombardment of 1 MeV helium ions. The channeling technique has been employed and three processes have been monitored simultaneously to explain the apparent reduction of damage at high doses, and to attempt to relate dechanneling processes to the types of defects that are created. A discussion of the basic channeling parameters is given, followed by a description of the common defects known to exist in alkali halides. An outline of the Pooley mechanism for the creation of F-centres, and the subsequent fate of these and their complementary interstitial defects, is presented. The experimental apparatus designed for the study of the emission of particles and photons, resulting from the bombardment is described together with the computerized data collection equipment. The importance of adequate monitoring techniques for the detection and recording systems is stressed.