EN
Fully differential cross sections are calculated for the ionization of helium by negatively charged fast projectiles using a semiclassical model developed previously for the ionization of atoms by positive projectiles. The method is tested in the case of 1 keV electron and 500 keV antiproton projectiles. The semiclassical results show reasonable agreement with the experiments and other theories. The origin of the obtained structures has been investigated by a partial wave analysis.