Positron impact elastic scattering by calcium atom using first order distorted wave born approximation with a complex potential

Abstract

Precise positron scattering cross section data are essential for the development of a wide range of technological fields such as astrophysics, plasma sciences, material sciences and bio-medicine. Thus, lack of complete agreement among the available theoretical data, unavailability of experimental data and the first-order distorted wave born approximation with a complex potential at impact energy range 10-200 eV not having been utilized in such a study; are the reasons that informed this investigation. After formulating the complex potential, with positronium formation channel proficiently incorporated, the radial equation was solved numerically. The extracted phase shifts were used to compute the transition matrix. The Roothaan-Hartree-Fock ground state wavefunctions of calcium were utilized in evaluation of the distorting potential and the transition matrix. The transition matrix was then used to determine the differential cross sections while the optical theorem was used to compute total cross sections. With only static potential, the present distorted wave Born approximation and optical potential models yield results that are in close agreement while the effect of positronium formation channel on the cross sections is insignificant at impact energies beyond 150 eV.