Near Threshold Electron Impact Ionization of Neon and Argon

Abstract

Electron-impact ionization of atoms is one of the basic process in physics in which few-body effects are illustrated. The most detailed information about electron impact ionization of atoms is available from (e,2e) experiments in which both electrons following an ionizing event are detected in coincidence. The kinematics of the collision is then fully determined and provides the measurement of triple differential cross sections (TDCS). In the past few years much effort has been devoted to the understanding of this process for the simplest atoms, and in particular, extensive studies have been performed on hydrogen and helium targets. At high energies (e.g. with excess energies of 100 eV and above) reasonable success has been achieved in describing the TDCS using a distorted wave Born approximation (DWBA)1. Below 100 eV the broad features of the experiment could be modeled in the DWBA description2,3 through the inclusion of polarization and post-collisional effects (PCI). This model has been able to reproduce the qualitative features of the TDCS down to few eV above threshold for both hydrogen4 and helium3.