Defect distributions in well-annealed polycrystalline Ni sputtered with low energy (3 and 5 keV) Ar(+) have been studied with a positron beam. The characteristics of the annihilation radiation were measured after the ion irradiation and after each step of an isochronal annealing up to 950degrees C. The simulated defect profiles consist of a close to the surface peaked distribution with a long tail into the sample. The isochronal annealing shows that the implanted species have a masking effect on the probe and the identification of open volume defects is just possible after partial annealing of the sample.