Stage I recovery (14-65°K) of electron-irradiated, high-purity copper is shown to be composed of at least five substages: ${\mathrm{I}}_A$, 14-24°K; ${\mathrm{I}}_B$, 24-28.5°K; ${\mathrm{I}}_C$, 28.5-33°K; ${\mathrm{I}}_D$, 33-48°K and ${\mathrm{I}}_E$, 48-65°K. ${\mathrm{I}}_A$, ${\mathrm{I}}_B$, and ${\mathrm{I}}_C$ recovery are discussed in further detail. (Discussion of ${\mathrm{I}}_D$ and ${\mathrm{I}}_E$ recovery is deferred to the following paper.) ${\mathrm{I}}_B$ and ${\mathrm{I}}_C$ are shown to have the characteristics of close-pair recovery. It is inferred that ${\mathrm{I}}_A$ also has these characteristics. The values of the activation energy for recovery are $E_A=0.05\mathrm{}\pm 0.01$ ev, $E_B=0.085\mathrm{}\pm 0.01$ ev, and $E_C=0.095\mathrm{}\pm 0.01$ ev. An attempt to relate the observed close-pair spectrum to specific interstitial-vacancy configurations is described.

• Received 28 January 1959

DOI:https://doi.org/10.1103/PhysRev.114.1452