Positron trapping at defects in evaporated films

The trapping of positrons at defects in evaporated copper and lead films has been investigated. Measurements of the positron lifetime spectra in high purity films over a wide range of deposition rates and a limited range of substrate temperatures can be interpreted in terms of positron trapping at both grain boundaries and dislocations in the copper films and at grain boundaries only in the lead films. Isochronal annealing studies indicate that recovery and recrystallization of these films is qualitatively similar to that of the bulk metal after deformation.