We have calculated differential cross sections as a function of the projectile scattering angle for positron-helium and positron-krypton collisions using the classical-trajectory Monte Carlo technique. These intermediate- velocity collisions have been simulated by various independent-electron and n-electron models, using both screened Coulomb and quantum model potentials to approximate the effects of electron-electron interactions. These several models all indicate that scattering of positrons to large angles in ionizing collisions persists to high impact velocities. In a previous work [Phys. Rev. A 38, 1866 (1988)] we proposed that the recent experiments that have measured the total cross section for positronium formation could be affected by the loss of positron flux due to incomplete confinement after large-angle scattering. Here, utilizing these newly calculated differential-scattering cross sections, adjustments are computed that account for the difference between the experimental and theoretical behaviors of the positronium formation cross section. Further, it is demonstrated that large angle scattering in the elastic channel is important for one of the experiments. We have also computed total cross sections for ionization and charge transfer for collisions of protons with krypton. Good agreement is obtained in these cases with experimental measurements. © 1989 The American Physical Society.
D. R. Schultz et al., "Large-angle Scattering In Positron-helium And Positron-krypton Collisions," Physical Review A, vol. 40, no. 9, pp. 4947 - 4958, American Physical Society, Jan 1989.
The definitive version is available at https://doi.org/10.1103/PhysRevA.40.4947
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01 Jan 1989