SOME ASPECTS OF COULOMB BREAK-UP PROBLEM : ATOMIC IONIZATION

Abstract

The work reported in this thesis aims at investigating some aspects of (e,2e) and (e,3e) reactions for the ionization of simpLe atomic targets by electron impact. Since the first (e,2e) experiments by Ehrhardt et at and Amaldi et al in 1969, a lot of effort has been devoted both to the theoretical and experimental determination of (e,2e) cross sections. The measurements have been carried out over a wide range of incident energies ranging from near threshold to several hundred keV. The experiments have been performed usually in two different kinematical arrangements. Weigold and coworkers have used symmetric geometry in which both the outgoing electrons are detected with about the same energy and at same angles with respect to the incident direction. At high energies such a geometry is very useful in obtaining momentum distribution of the initially bound target electrons. Ehrhardt and coworkers have pioneered coplanar asymmetric geometry in which one of the electrons (scattered) is detected at relatively small scattering angle with energy close to the incident one, and the cross section is measured as a function of the scattering angle of the other (slow, ejected) electron. This type of geometry provides a particularly sensitive test for any model describing the dynamics of the collision process. The quantity of interest in all these is the triple differential cross section (TDCS) which provides the most detailed information about an (e,2e) reaction. A good understanding of this process has been gained at intermediate and high impact energies. Therefore current experimental and theoretical efforts are concentrated at low energies and close to ionization threshold region.