Coincidence Studies of Electron and Photon Impact Ionization

The great advantage of coincidence measurements is that by suitable choice of the kinematical and geometrical arrangement one may probe delicate physical effects which would be swamped in less differential experiments. The measurement of the triple dif­ ferential and higher-order cross sections presents enormous technical difficulties, but refined experiments of this type provide an insight into the subtleties of the scattering process and offer a welcome, if severe, test of the available theoretical models. The last few years have been an exciting time to work in the field and much has been learned. Profound insights have been gleaned into the basic Coulomb few body problem in atomic physics: the experimental study of the fundamental (e,2e) processes on hydrogen and helium targets continues to add to our knowledge and indeed to challenge the best of our theoretical models; significant advances have been made in the understanding of the "double excitation problem," that is the study of ionization processes with two active target electrons: important measurements of (e,3e), (,),,2e), excitation-ionization and excitation autoionization have been reported and strides have been made in their theoretical description; the longstanding discrepancies between theory and experiment for relativistic (e,2e) processes were resolved, spin dependent effects predicted and ob­ served and the first successful coincidence experiments on surfaces and thin films were announced. Theory and experiment have advanced in close consort. The papers pre­ sented here cover the whole gambit of research in the field. Much has been achieved but much remains to be done.

Contenu

Recent Absolute (e,2e) Measurements on Atomic Hydrogen and Helium at Low and Intermediate Energies; H. Ehrhardt, J. Röder. Second Born Calculations of (e,2e) Cross Sections at Low Energy Using a Pseudo-State Set; F. Rouet, et al. Excitation-Ionization and Excitation-Autoionization of Helium; P.J. Marchalant, et al. An Analytical Approach to Resonant and Direct Fragmentation of Many-Body Coulomb Systems; J. Berakdar. Ionization Dynamics and Exchange Effects in Pure Three-Body Coulomb Scattering; J. Berakdar, J.S. Briggs. Analysis of Integrated Cross Sections and Spin Asymmetries for the Electron-Impact Ionization of One and Two-Electron Atomic Systems; J. Berakdar, et al. Double Ionizaton Mechanisms from Triple Coincidence Experiments; A. Lahmam-Bennani, et al. Double Ionization of Helium by Electron Impact: A Study of the Two Step Mechanism; C. Dal Cappello, et al. Partitioning of Momentum in Electron-Impact Double Ionization; J.H. Moore, et al. 5DCS and 4DCS Calculations for Symmetric (e,3e) Impact Ionization; Yu.V. Popov, et al. Exact and Approximate Methods of the Rigorous Coulomb Scattering Theory; I.V. Farnakeev, et al. Strong and Weak Statements in the Theory of Dipolar (e,2e) Impact Ionization; Yu. Popov, et al. Exact and Approximate Methods of the Rigorous Coulomb Scattering Theory; I.V. Farnakeev, et al. Strong and Weak Statements in the Theory of Dipolar (e,2e) Impact Ionization; Yu. Popov, et al. 25 Additional Articles. Index.