Excitation of the hydrogen atom from its ground and metastable states by positron and proton impact at intermediate energies

Abstract

Differential and integral cross sections for five transitions (1s-ns (n=2, 3, 4) and 2s-ns (n=3, 4)) of the hydrogen atom by positron and proton impact are calculated, in the framework of the distorted-wave approximation. A comparative study is made by taking distorted waves (Coulomb waves) either in the initial channel or in the final channel or in both the channels. The energy range studied for positrons is from 100 to 500 eV and for protons from 100 to 500 keV. The computed results are compared with the plane-wave results and other available theoretical results.