Radiation-annealing effects in energetic displacement cascades

Radiation-annealing effects due to energetic displacement cascades have been studied in copper, silver, and gold using electrical-resistivity measurements of thin-film specimens. It was found that close Frenkel pairs are unstable in the region of an energetic cascade. This was shown by doping the specimens with Frenkel pairs using a 150-keV proton irradiation at low temperature and measuring the damage rate during a subsequent heavy-ion irradiation. For ∼ 500-keV self-ion irradiations the volume around the cascade in which close Frenkel pairs are unstable is 5 × 10-16, 2 × 10-16, and 4 × 10-17 cm3 for silver, gold, and copper, respectively. Moreover, it was observed that the volume increased with increased energy density in the cascade. The implications of these results on defect production, defect saturation behavior, and isochronal recovery for damage produced in energetic cascades are discussed.