18 research outputs found
Convergent close-coupling method for positron scattering from noble gases
We present the convergent close-coupling formulation for positron scattering from noble gases (Ne, Ar, Kr and Xe) within the single-center approximation. Target functions are described in a model of six p-electrons above an inert Hartree–Fock core with only one-electron excitations from the outer p6 shell allowed. Target states have been obtained using a Sturmian (Laguerre) basis in order to model coupling to ionization and positronium (Ps) formation channels. Such an approach is unable to yield explicit Ps-formation cross sections, but is valid below this threshold and above the ionization threshold. The present calculations are found to show good agreement with recent measurements
Management of Domestic Violence by Primary Care Physicians in Hong Kong: Association With Barriers, Attitudes, Training, and Practice Background
Capture cross section with ionization for collisions of a helium atom with protons. Calculation by the continuum-distorted-wave method
Positron scattering from noble gases
We have extended the nonrelativistic convergent close-coupling (CCC) method to the calculation of positron scattering from noble gases within the single-centre approximation. Good agreement is found with the available measurements of total cross sections and elastic differential cross sections for Ne, Ar, Kr and Xe
Low-energy positron interactions with xenon
Low-energy interactions of positrons with xenon have been studied both experimentally and theoretically. The experimental measurements were carried out using a trap-based positron beam with an energy resolution of ~80 meV, while the theoretical calculations were carried out using the convergent close-coupling method and the relativistic optical potential approach. Absolute values of the grand total, positronium formation and grand total minus positronium formation cross sections are presented over the energy range of 1–60 eV. Elastic differential cross sections (DCS), for selected energies, are also presented both below and above the positronium formation threshold. Fine energy-step measurements of the positronium formation cross section over the energy range of 4.4–8.4 eV, and measurements of the elastic DCS at the energies of 5.33 and 6.64 eV, have been carried out to investigate the ionization threshold regions corresponding to the 2P3/2 and 2P1/2 states of the Xe+ ion. The present results are compared with both experimental and theoretical values from the literature where available