A STUDY OF -IONIZATION IN ATOMIC COLLISIONS AT INTERMEDIATE AND HIGH ENERGIES

Abstract

The work reported in this thesis is author's attempt to study the ionisation process, at intermediate and high energies, in which a beam of charged particles (e.g.electrons) is bombarded onto an atomic hydrogen or helium target. In this work, first Born, second Born, Coulomb-projected Born and Glauber approximations have been used as a tool to investigate the triple differential cross section (TDCS) for the ionisation process. In the first chapter of this thesis, we have given a general introduction of the subject and have indicated the notations to be used. Various approximate methods, which have been referred/used in the present work, are briefly reviewed in the second chapter. In third chapter the Coulomb-projected Born (CPB) approach for the ionisation of atomic hydrogen is extended to include polarisation effects. The results (TDCS) are compared with the experi-mental data of Weigold et al(121) and with the distorted-wave results of Smith et al(103) in the energy range 100-250 eV. It is found that the present results show a substantial improvement over the usual CPB results for small scattering angles and are quite close to those of Smith et a1, The fourth chapter deals with the calculations of TDCS for the electron impact ionisation of helium in CPB and polarised CPB approximations. The results have been compared with various recent coplanar and non-coplanar measurements.