Application of positron beam Doppler broadening technique to ion beam irradiation in nickel

The formation processes of vacancy-type defects induced by ion irradiation in nickel were investigated with a variable-energy positron beam Doppler broadening technique in order to find the appropriate experimental condition for in situ positron beam experiments. Nickel ion irradiation at 300-343 K induces an S parameter increase, but the dependence of the S parameter on positron energy is very similar to that of cold-rolled nickel, which suggests positron trapping by small vacancy-type defects such as SFTs. The best experimental condition for investigation of cavity nucleation process by in situ positron beam Doppler experiments is suggested to be around 0.1-0.4 dpa at 773 K