Post-collisional interaction effects in the electron and positron impact ionization of neutral atoms

Triple differential cross sections (TDCS) are presented for the electron and positron impact ionization of neutral atoms in coplanar asymmetric geometry. Using both positrons and electrons as projectiles has opened up the possibility of performing complementary studies which could effectively isolate competing interactions which cannot be separately detected in an experiment with a single projectile. In this paper, the role played by post-collisional interaction (pci) between the ejected electron and the scattered projectile is studied. (e(-), 2e(-)) experimental results for atomic hydrogen where the role of pci is well-understood are considered, and it is shown that a classically corrected first Born approach gives better agreement with the shape and absolute size of the experimental data than either using the Gamov N-e-(e)- or the Ward-Macek M-e-(e)- correction factors. Predictions are presented for the TDCS for positron impact ionization of hydrogen. The insights gained from the hydrogen study are applied to the electron and positron impact ionization of argon.