Variations of the Dislocation Damping Coefficient during Gamma Irradiation of NaCl Single Crystals

Abstract

Deformed sodium chloride crystals were irradiated by γ rays from spent fuel elements while their ultrasonic properties (resonant frequency and decrement) were being measured. It was found that the damping coefficient associated with the viscous drag on a moving dislocation varied with time during irradiation, and was also a function of the state of deformation of the crystal. The variations in the damping coefficient were interpreted in terms of the model developed by Robinson and Birnbaum for dislocation damping in alkali halides.