Electron Irradiation of Copper Near 10°K

Abstract

The resistivity change induced by electron irradiation of zone-refined copper maintained at ∼10°K has been measured over the range of bombarding electron energies from 0.70 to 1.37 Mev. The cross section for damage production is shown to be insensitive to the choice of the shape of the displacement probability function for this energy range. An "average" threshold energy for displacement of 22±3 ev is deduced, from which the resistivity of Frenkel pairs, ${\rho }_f=1.45\mathrm{}\pm 0.5$ μohm cm/atomic% is obtained. Isochronal and isothermal annealing studies of irradiations performed at 1.37 Mev are described. The maximum annealing rate, as obtained from an isochronal anneal, occurs at ∼40°K; ∼90% of the irradiation-induced resistivity annealing out in the range 20°K-65°K. The isothermal annealing curves are not amenable to analysis in terms of a single simple rate process, but seem to require a multiplicity of processes.