# Doubly differential cross section (DDCS) for single ionization in collisions of 300 keV H^{+} on Ar targets as a function of the electron energy for 10°, 30° and 50° fixed emission angle

**Figure 1.** Doubly differential cross section (DDCS) for single ionization in collisions of 300 keV H^{+} on Ar targets as a function of the electron energy for 10°, 30° and 50° fixed emission angle. Theory: *full line*, *complete post*-CDW-EIS calculations with effective charges; *short dotted line*, *post*-CDW-EIS calculations with effective charges; *dotted line*, *post*-CDW-EIS calculations with asymptotic charges; *dashed line*, *prior*-CDW-EIS calculations with effective charges; *chain line*, CDW-EIS calculations from Gulyás *et al* [27]. Experiment: *symbols*, Rudd *et al* [24].

**Abstract**

A complete formulation of the *post*-version of the continuum distorted wave-eikonal initial state (CDW-EIS) model is used to investigate single ionization of multishell atoms by fast bare proton beams. The influence of the non-ionized electrons on the dynamic evolution is studied for each of the different shells of the targets. Its inclusion was made by means of the parametric Green–Sellin–Zachor potential. In this way, it is shown that discrepancies between the *prior-* and *post*-versions of the CDW-EIS model are avoided for any *nl* states of the systems studied here. The present analysis is supported by comparisons with existing experimental electron emission spectra.