Positron scattering from argon and krypton

The elastic cross-sections for positron scattering from Ar and Kr have been determined by the polarized-orbital method while the excitation cross-sect ions have been calculated within a distorted-wave framework in an energy ra nge up to 200 eV. The excitation cross-sections are compared with available experimental results for argon. We analyze the relative contributions to the total cross-section of our ela stic and excitation cross-sections and of the cross-sections, calculated by other authors, for positronium formation and for ionization. We compare th ese results with experimental measurements for the total cross-section. Our results are in satisfactory agreement with the experimental measurement s except at low energies, where positronium formation is important. (C) 200 0 Elsevier Science B.V. All rights reserved.