The energy dependence of proton, deuteron, and Helium-Ion radiation damage in silver, platinum, and gold

The energy dependence of light-ion radiation damage has been studied with Ag, Pt, and Au as target materials. The projectiles were 4-13 MeV p and d and 12-20 MeV 3He and 4He. As a measure of the damage introduced, we used changes in electrical resistivity. All measured damage-rate curves show strong saturation effects. The energy dependence is roughly E-11nE as expected from a Rutherford-recoil spectrum, but deviations from this behaviour due both to deviations of the recoil spectrum from a pure Rutherford and to electronic energy losses of the recoil atoms are seen. Although a detailed quantitative fit to existing theories is not possible, several independent pieces of evidence indicate a substantially higher effective threshold displacement energy in gold than in platinum.