Dynamics of transfer ionization inp-He collisions at intermediate energies

We have performed a kinematically complete experiment for transfer ionization, i.e., the capture of one target electron by the projectile accompanied by the ejection of a second electron, for 50--100 keV $p$-He collisions by means of a reaction microscope. It was found that the electron momentum distribution projected onto the scattering plane is consistent with the prediction of an independent two-step mechanism involving a binary encounter. The deviation of the electron momentum distribution from the ideal binary ridge is attributed to binding energy effects and the interaction between the electron and the residual recoil ion. The good agreement between our measurements with the dynamic-screening classical trajectory Monte-Carlo calculations strongly suggests that electron-electron correlations play an important role in this two-electron process.