High energy limit of photon-atom interactions: example of double ionization of He by photoabsorption

R. H. Pratt¹, E. G. Drukarev² and T. Suri<sup>3

1</sup>Department of Physics and Astronomy, University of Pittsburgh,
Pittsburgh, PA 15260, USA,
²Petersburg Nuclear Physics Institute, Gatchina,
St. Petersburg 188350, Russia,
³R. Bokovi Institute, P. O. Box 1016, 10000 Zagreb, Croatia

Abstract:

An important class of high energy atomic processes can be understood from the theory of asymptotic Fourier transforms. The asymptotic behavior is determined from the singularities of initial and final state many-body wave functions and interactions. These in turn follow from the singularities of the interaction between particles. Final results are gauge and form independent, but dependence on the quality of initial and final wave functions varies with gauge and form. We illustrate these ideas in a discussion of the double ionization of helium in photoabsorption, relating the dominant absorption mechanisms to electron-nucleus and electron-electron coalescences.