Report on the heavy ion separator SIS at the GSI

For the on-line separation of unslowed nuclear reaction products a velocity filter has been built. The arrangement consists of two separator stages. The separation in each stage is achieved by two homogeneous magnetic fields and a homogeneous electric field. The second stage cancels the velocity dispersion generated by the first stage. Independently from the separation the particles are focussed by quadrupole triplets. A short description of the technical details is given as well as a report concerning the first experiences with the apparatus. Finally planned detection methods and experiments are discussed. (Auth.)