Multiple Scattering Mechanisms in Simultaneous Projectile-Electron and Target-Electron Ejection in H⁻ + He Collisions

We studied simultaneous electron ejection from both collision partners in 200-keV H-+He collisions in a kinematically complete experiment by measuring the fully momentum-analyzed recoil ions and both active electrons in coincidence. The data were analyzed in terms of Dalitz spectra, in which the momentum exchange between three particles is plotted simultaneously in a single spectrum. We found that the energy transfer occurs predominantly between the active electrons, but most of the momentum is exchanged in elastic scattering between the cores of the collision partners