Double ionization of helium by 3.6 MeV/u Au53+ impact

A kinematically complete experiment for double ionization of He by 3.6 Mev/ u Au53+ impact has been performed using a high-resolution integrated multi- electron recoil-ion momentum spectrometer. Nine out of twelve momentum comp onents of the outgoing fragments were measured. The electrons sum-momentum is found to be in the forward direction and the recoil ion almost compensat es the electrons being ejected into the backward hemisphere. The momentum c hange of the projectile is found to be small compared to the momenta of the ejected reaction products, which reveals similarity with photoionization. The strongest interaction among the collision partners is found to exist be tween the recoil ion and the electrons.