A study of critical minima and spin polarization in the e^±–Ba elastic scattering

A complex optical potential (OP) is employed to study the critical minima (CM) and spin polarization in the elastic e⁻–Ba and e⁺–Ba scattering for collision energies in the range E_i = 1–1500 eV and E_i = 1–100 eV respectively in terms of the Dirac partial wave method (OPMD) and the Schrödinger partial wave method (OPMS). The energy dependence of the integral elastic cross sections (IECSs), momentum transfer cross sections (MTCSs), viscosity cross sections (VCSs), inelastic cross sections (INCSs) and total cross sections (TCSs) is also calculated and discussed for both the projectiles in the same energy range. The OPMD optical potential is composed of the static, exchange, polarization and absorption components. On the other hand, the OPMS comprises the static, local exchange, polarization, spin–orbit, and absorption potentials. The number of CM in the DCS distribution of e⁻–Ba scattering has been found to be 11 using the OPMD method, while the OPMS calculation produces 12 CM points. However, the OPMS calculation with the static and spin–orbit potentials only produces 9 CM. The critical energies and the angular positions of these CM are revealed and discussed. There are 22 and 24 maximum spin polarization points found in the e⁻–Ba scattering using OPMD and OPMS respectively. For the case of e⁺–Ba scattering, we have found 2 CM with OPMD calculations of which the angular positions along with the critical energies are discussed. There are 4 maximum polarization points noted with OPMD calculations which fail to attain the condition for sharpness of S(θ) distribution. To the best of our knowledge, the present is the first work to determine the CM in the DCS distribution of e^±–Ba scattering. The Sherman function and the DCSs for some energy points are also calculated for the first time.