IONIZATION COLLISION DYNAMICS IN 3.6 MEV U NI24+ ON HE ENCOUNTERS/

The momentum balance between all emerging particles (electron, recoil ion and projectile) was explored for single ionization of helium by 3. 6 MeV/u Ni24+ impact in a kinematically complete experiment. Technical ly this was achieved by integrating a novel 4 pi low-energy electron a nalyzer into a high-resolution cold-target recoil-ion momentum spectro meter. More than 90% of the ''soft electrons'' (0 eV less than or equa l to E(e) less than or similar to 50 eV) are ejected in forward direct ion with a most probable longitudinal energy (along the ion-beam) of ( $) over bar E(e parallel to) approximate to 3 eV. Not the projectile, but the backwards ejected recoil-ion (<($)overbar>E(R parallel to) app roximate to 0.4 meV) compensates the electron longitudinal momentum ex cept of a small contribution from the inelasticity of the reaction. En ergy losses of the 0.2 GeV projectiles as small as Delta E(p)/E(p) = 3 .4 x 10(-7), transverse momentum balances, as well as electron energy and angular distributions for defined final recoil-ion charge state be come accessible with this technique.