Energy dependence of the defect production at 93 K In electron-irradiated copper

Abstract

The ratio of the cross sections for defect production at 93 K and 8 K irradiation temperature has been measured as function of electron energy between 0.4 MeV and 3.2 MeV. As result this ratio amounts to 0.4 and does not depend on energy within the energy range investigated. From this result and the well-known energy dependence of the fraction of close pair annealing the energy dependence of the average displacement distance of freely migrating interstitials is derived. The obtained increase of this distance with decreasing energy is explained by a simple model which uses two different displacement mechanisms differing in the specific energy losses.