We report on angular distributions of electron emission at 600 eV and 300 eV in 1 MeV proton-He collisions, in coincidence with electron capture by the projectile. The angular distribution of electrons in the vicinity of the beam velocity (600 eV) exhibits peaks at 58° and 90°, while the distribution of 300 eV electrons peaks at 68° and 110°. The forward peaks are due to a process in which the proton interacts with each of the two target electrons leading to capture and ionization. The features of peaks at 90° and 110° are ascribed to a two-step process of proton-electron scattering in the first step and a localized interaction of electron-electron scattering (correlation) in a second step, in which one of the electrons is deflected into a bound state of H° while the other electron is ionized. The magnitudes of our measured absolute cross sections for the proton-electron-electron scattering processes agree within factors of two to eight with recent theoretical predictions.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Mathematical Physics
- Condensed Matter Physics