[en] The process of ionization in ion-atom collisions was investigated. Thus absolute double differential electron emission yields were measured for the collision system H⁺+He. The experimental results are compared with theoretical results partially calculated in this work. For the coincidence measurements an electron time-of-flight spectrometer with a large solid angle was constructed. For the measurement of the scattered projectiles a fast position sensitive ion detector and a data preprocessing unit were developed. (orig.)