INFLUENCE OF DISLOCATIONS ON POSITRON LIFETIME IN IRON

To clarify 'medium' lifetimes of similar to 150 ps in deformed iron, w e calculate the positron lifetimes at the core of dislocations and rel ated defects in iron. The calculations are based on an empirical N-bod y interatomic potential by Finnis and Sinclair for the atomic arrangem ents and the local-density approximation for the positron-electron cor relation. We find the positron lifetime for vacancies associated with edge dislocation to be the medium lifetime, while that for vacancies a ssociated with screw dislocation is almost the same as the single-vaca ncy value. The positron lifetimes for pure dislocations and for jogged dislocations are close to the perfect-lattice value.