Theoretical premises for experimental verification of the deviations from the wannier threshold behaviour

Abstract

The Wannier [1] theory describes the escape of two electrons from a charged core in the threshold domain. Its modification [3] is applied to some features of the double escape processes which were not analyzed previously in due extent. The behaviour of the total cross sections for a small, but finite, energy excessE above the threshold is described incorporating the deviations from the well known Wannier power law. The processes with the escape of electron and positron from the core are also considered. The energy dependence of the spin asymmetryA in (e, 2e) collisions is analyzed in connection with the recent experimental data (which seem to manifest some dependenceA(E) in the near-threshold domain contrary to the conventional Wannier theory). The theory suggests the requirements for the accuracy of the experiments intended to verify the Wannier threshold laws and detect the deviations from them.