Projectile angular distribution in He single ionization by proton impact as a function of the ejected-electron energy

In this paper we study the single ionization of helium atoms by the impact of protons at intermediate energies. We present a continuum-distorted-wave--eikonal-initial-state calculation of the cross section doubly differential in the projectile scattering angle and the ionized electron energy. The internuclear interaction is incorporated by means of an eikonal phase approximation. This calculation includes a full account of the final-state interactions among the three collision partners, showing a much better agreement with the recent experimental data of Schulz et al. than other first-order theories. We also discuss the appearance of different structures associated with the electron capture to the continuum process and the binary-encounter projectile-electron collision.