Positron annihilation study of defects in copper irradiated with swift Xe26+ ions

Variable energy positron beam and conventional positron lifetime spectroscopy were used to study pure copper exposed to irradiation with 167 MeV Xe26+ heavy ions with different doses of 1012, 1013, 5 × 1013, 1014 ions/cm2. The presence of vacancy-type defects induced by implantation was confirmed in Doppler spectroscopy characteristics. Decreasing of the positron diffusion length from 135 nm for unirradiated sample, to 82 nm for the lowest and to 46 nm for the highest applied dose was noted. It points out increasing defect concentration with the increase of the fluence. Additionally, the existence of one kind of defects in all irradiated samples was noticed. The defected zone covered with the implanted range and the so called “long range effect” was not confirmed.