ELECTRONIC EXCITATION OF H-2 BY POSITRON-IMPACT - AN APPLICATION OF THE SCHWINGER MULTICHANNEL METHOD

In this paper we report integral and differential cross sections for p ositron-impact excitation of the X 1SIGMA(g)+ --> B 1SIGMA(u)+ transit ion in H-2 for collision energies of 13.5, 15, 17.5, 20, 25 and 30 eV. These cross sections were derived from fixed-nuclei scattering amplit udes in such a way that low angular-momentum components are obtained u sing the Schwinger multichannel method and the large ones are treated by the first Born approximation. To our knowledge, up to date no exper imental data are available for comparison. Our results differ from pre vious theoretical results of Mukherjee and co-workers. We discuss poss ible reasons for this disagreement.