A simple double screening model was used to calculate the interaction potential between an energetic channelled + and an impurity (O) in an otherwise perfect monocrystal (Ta). The 2-fold screening of the nuclear charge of the impurity was due firstly to the atomic electrons and secondly to the conduction electrons of the host crystal (Ta). By using this potential, the dechannelling cross-section of muons, due to O impurities along various planes in the Ta lattice, was evaluated. Three charge states of the O impurity were considered and the corresponding dechannelling cross-sections were predicted.

A.M.Siddiqui, V.Harikumar, A.P.Pathak: Physica Status Solidi B, 1994, 185[1], 77-85