Strong projectile-energy dependence of the Auger-line intensity at due to Coulomb focusing in fast proton - neon collisions

The variation of the intensity of the Ne K - Auger line due to post-collision interaction has been measured as a function of the projectile energy at observation angle in 0.8 - 3.2 MeV - Ne collisions. The measured Auger-electron yield normalized to the theoretical or experimental total K-shell ionization cross section shows a strong enhancement when the projectile velocity is smaller than the Auger-electron velocity. The general agreement between the present experimental data and continuum distorted wave calculations provides a clear evidence that the observed impact-energy dependence is mostly due to the post-collision Coulomb focusing exerted by the projectile on the Auger electron.