DOUBLE IONIZATION OF HELIUM BY FAST ELECTRON IMPACT A. Dorn1, R. Moshammer1, C.D. Schroetter1, T.J.M. Zouros2, W. Schmitt1, H. Kollmus1, R. Mann3 and J. Ullrich1 1Universitaet Freiburg, Hermann-Herder-Str.3, 79104 Freiburg, Germany 2Department of Physics, University of Crete, 71003 Heraklion, Greece 3Gesellschaft fuer Schwerionenforschung, 64220 Darmstadt, Germany Using combined multi-electron - recoil-ion spectroscopy a kinematically complete experiment for double ionization of He by 3 keV electron impact has been performed. This technique allows for the first time to study the many particle dynamics of (e,3e) collisions over the complete four-particle final state momentum space.