Positron-impact ionization of hydrogen atoms

Abstract

The ionization cross section of hydrogen atoms by positron impact has been calculated by using a distorted-wave polarized-orbital method. We have employed two models depending on the choice of the final-channel wave function, and the two sets of results differ dramatically. We have also found that below 100 eV the total positron-impact ionization cross section including positronium formation is appreciably larger than the corresponding results for electron-impact ionization.La section efficace d'ionisation de l'atome d'hydrogene par impact de positrons a CtC calculCe en utilisant une methode d'orbitale polarisCe avec distorsion d'onde. Nous avons employ6 deux modeles dtpendant du choix de la fonction d'onde du canal final, et les deux series de rCsultats different dramatiquement. Nous avons aussi trouvC qu'au-dessous de 100 eV, la section efficace totale d'ionisation par impact de positrons, incluant la formation de positronium, est apprCciablement plus grande que la valeur correspondante pour I'ionisation par impact d'tlectrons.[Traduit par le journal]Can. J. Phys. 63, 621 (1985)

Positron Impact Ionisation of H and He Atoms: The Continuum Model

“…1. The cross sections calculated by the COM, the DW model 1 (DWl) of Ghosh et al (1985) and the 'best' model of Mukherjee et al (1989) are compared with the experimental data of Spicher et al (1990). All the theoretical calculations predict a qualitative shape that is in fair agreement with experimental measurements.…”

“…For the e+ -H case, there are the distorted-wave polarised orbital (DWPO) calculations of Ghosh et al (1985) and the distorted-wave (DW) calculations of Mukherjee et al (1989). Other calculations include the classical Monte Carlo trajectory-type methods of Ohsaki et al (1985) and Wetmore and Olson (1986).…”

Ionization cross sections in e+-H2scattering

“…As a check of the Coulomb functions in our program, we have reproduced the results of the FBA ionization cross section of e f + H by Ghosh et al (1985) to within 1%.…”

The physics of low-energy positron collisions

“…This leads to the plot shown in Fig. 11 which presents the ratios o,(e+)/a,(e-) and a,(p+)/a,(p-) for the He gas where the latter data were taken from a calculation [54]. It is evident that (7) down to velocities (energies) close ( E -E, -1OeV) to the threshold for the light particles.…”