Energy and angular distributions in 250 eV electron and positron collisions with argon atom

We present energy and angular differential cross sections for single-ionization in collisions between electrons and positrons with argon atoms at 250 eV. We treat the collision classically using the three body approximation where the target atoms are described within the single active electron approximation using a Garvey model potential and only the outermost electron is involved in the collision dynamics. Our present classical trajectory Monte Carlo model is shown to describe the ionization cross sections reasonably well and agree with existing experimental data. We show that the energy distributions, both for electron and positron impact, have the same shape and structure. In contrast, the angular distributions for electron and positron impact behave completely different which it maybe be attributed to the projectile-target core interaction. We present also the ionization probabilities as a function of impact parameter. We found that for the case of positron impact the distribution is symmetric, while for the case of electron impact the distribution is asymmetric.