Annihilation of positrons with core electrons of transition metal impurities in copper

Abstract

Positrons annihilate more frequently with core electrons (including 3d electrons) of transition metal impurity atoms (Ni, Co, Fe and Cr) in copper than those of matrix copper. This effect is insensitive to the impurity atoms on the right hand side of copper in the periodic table such as Ge. The trapping model of impurity atoms is discussed.