Importance of angular and radial electron correlations in first born (e, 2e) spectroscopies of heliumlike targets

The ground-state electronic structure of heliumlike systems can be described by several simple wave functions expressed in terms of the three distances between particles (one nucleus and two electrons). The dependence of (e, 2e) ionization cross sections on the description of radial and angular correlations between target electrons is analyzed. The cases of plane wave and Coulomb wave representations of ejected electron trajectories are examined together with the feasibility of analytic calculations. The relative sensitivity of (e, 2e) cross sections to the description of correlations between K-shell electrons is also investigated as a function of nuclear charge. Existing experimental data on helium are used to support a comparison with calculated (e, 2e) cross sections.