Stored-Energy Release Below 80°K in Deuteron-Irradiated Copper

Measurements were made of the release of stored energy during the annealing from 15 to 80°K of copper irradiated with 11-MeV deuterons. A differential thermometry technique using two closely matched specimens, one of which was irradiated, was employed. Loss corrections and heat capacities were determined for the range of temperature of annealing. Two irradiations, with different total damage dose, and subsequent anneals were made. Good definition of the peak substructure in stage I was obtained. The magnitude of the energy released is consistent with the interstitial-vacancy annihilation mechanism of radiation damage annealing. The energy-to-resistivity ratio found is in disagreement with the ratios obtained previously for neutron and electron damage. Assignments are obtained for the volume change, resistivity, and number of Frenkel pairs introduced in a damaged copper specimen for a given assumed value of the energy of a Frenkel pair. The results are compared with theory.