Relativistic approach for e^± scattering from argon

Relevant data is available at: http://www.astronomy.ohio-state.edu/~nahar/nahar_radiativeatomicdata/index.htmlDifferential and integrated elastic, integrated total cross sections as well as various polarization parameters-the spin polarization P and the parameters T and U describing the change in the polarization vector during scattering-for the scattering of electrons and positrons from argon in the energy range of 3-300 eV are calculated using the relativistic Dirac equation. The real part of the projectile-target interaction is represented by a sum of model potentials. The phase shifts for large angular momenta ħl are calculated using the Born approximation. The relativistic calculations for the differential and integrated elastic cross sections obtained using the pure real potential show almost no improvement over those obtained nonrelativistically for positron scattering from argon while similar calculations show some effects, except at low energies (≤ 5 eV) where relativistic terms are sensitive to the form of potentials used, on the values of the differential cross sections for electron scattering from argon. The polarization parameter P for electron scattering is found to be in good agreement with various calculated and measured values. A few different models of the absorption potential for the inelastic processes are used to calculate the integrated inelastic and the integrated total cross sections for positron and electron scattering from argon. It is noticed that even though the integrated elastic and the integrated total cross sections for the scattering of positrons and electrons calculated using some complex model potential agree well with the corresponding measured values, the differential cross section curves using the same model potentials can differ considerably from each other as well as from the experimental values.Support of Air Force Office of Scientific Research (Grant No. AFOSR-87-0342) is gratefully acknowledged