L-shell ionization by antiprotons.

Abstract

Semiclassical coupled-state model calculations have been performed for L-shell ionization of gold induced by protons and antiprotons in the energy range 0.15--3 MeV. The results of the calculations have been compared with the predictions of a simple approach suggested by Brandt and Basbas for description of antiparticle excitation of atomic inner shells. Apart from the range of very low collision velocities, a reasonable agreement has been found between the two models. In addition to the binding and Coulomb-distortion effects discussed by Brandt and Basbas [Phys. Rev. A 27, 578 (1983); 28, 3142(E) (1983)], for the L shell a further effect due to dynamical couplings between the L-substate ionization amplitudes also contributes to the particle-antiparticle differences. While the latter processes have only a negligible effect on the energy dependence of the cross sections, their inclusion has been shown to be unavoidable when ratios of the subshell ionization cross sections are analyzed for the two kinds of excitation.