Three-dimensional fully differential single ionization cross sections for 75 keV p+He collisions

We have studied fully differential cross sections (FDCS) for single ionization in 75 keV p + He collisions by measuring the recoil-ion momentum and the projectile momentum in coincidence. The measured FDCS are completely dominated by the binary peak while the recoil peak is absent. This is a clear signature of the post-collision interaction between the outgoing projectile and the ejected electron. Furthermore, our continuum distorted wave calculation demonstrates the importance of the projectile-target nucleus interaction. While the shape of the experimental FDCS is well reproduced by this calculation, there are significant discrepancies in magnitude.