Expansion of Copper upon Low-Temperature Deuteron Irradiation

The increase in linear dimensions of a 99.999% copper foil upon deuteron irradiation was measured directly as a function of integrated flux. Two bombardments were made on the same specimen with integrated fluxes of 3.14×${10}^{16}$d/${\mathrm{cm}}^2$ and 7.68×${10}^{16}$d/${\mathrm{cm}}^2$, respectively. It was found in both runs that the specific change in length per incident deuteron per square centimeter was 3.8×${10}^{-21\mathrm{}}$. This value applies to an average deuteron energy of 8.5 Mev. Measurements of the thermal recovery of the irradiation-induced change in length were also made. If the stages of thermal recovery between the bombardment temperature and room temperature are designated as Stage I (70°K), Stage II (70-180°K), and Stage III (180-300°K), then the amount of recovery per stage is 64%, 6%, and 26%, respectively. The residual effect remaining at 300°K is 4% of the maximum effect. It is suggested that the defects introduced by the deuteron irradiation are Frenkel pairs and that thermal recovery proceeds by means of recombination of vacancies and interstitials between the bombardment temperature of 17° and 300°K.