Using a purely electrostatic positron beam, the total cross section of positrons scattering from H_{2}O has been measured for the first time with a high angular discrimination (≃1°) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of...

The process of electron-positron pair creation by a high-energy electron in a medium is analyzed. The spectral distribution over energies of created particles is calculated for the direct and cascade mechanisms of the process. The Coulomb corrections are included. The new formulation of the equivalent photons method is developed which takes into account the influence of multiple scattering. It ...

The elastic low-energy positron scattering on Be, Mg, Ca, Sr, Ba and Ra atoms has been investigated at energies below 100 eV. The ab initio calculated polarization potentials applied in these calculations were obtained by solving the coupled Dirac-Hartree-Fock equations. Comparison between present results and those of previous model calculations shows serious discrepancies. Particularly, we do ...

Abstract We present R-matrix calculations of electron and positron low energy scattering from the highly polarizable pyrazine molecule. compare integral differential elastic cross sections with experimental results assess quality models used for describing collisions either projectile. Static-exchange-plus-polarization give a good description (including that shape resonances), whereas both smal...