Total cross sections for positron scattering on argon and krypton at intermediate and high energies

Preliminary total cross section data for positron scattering on argon and krypton between 250 and 5000 eV are presented. A Ramsauer-type apparatus, previously used for electron-scattering measurements has been modified. To check for the convergence between electron and positron total cross sections, a semiempirical analysis has been applied. The analysis for argon indicates an asymptotic convergence for electron and positron projectiles - the high energy parameters of the both fits are equal within the uncertainty limits. No such a clear conclusion is possible with the present data up to 5000 eV for krypton. (C) 2002 Elsevier Science B.V. All rights reserved.