SCATTERING AND TRAPPING OF POSITRONS AT VACANCIES IN SOLIDS

Calculations of the positron trapping efficiency at vacancies and thei r clusters in the transition limit within the optical potential approa ch are presented. The results are compared with the results of the app roach based upon Fermi's golden rule reported in the literature. No si gnificant differences are found either for metals or semiconductors. T he calculations show that the elastic scattering of positrons at vacan cies and their clusters is more important than trapping. The absorptio n coefficients for positrons at vacancies and their clusters in alumin ium and silicon are evaluated.