Stochastic precooling of heavy fragments in the ESR

In the new accelerator complex at GSI, exotic nuclei will be produced and separated in a fragment separator downstream the synchrotron SIS. Beams of these nuclei are expected to have low phase space densities. In the cooler ring ESR, therefore, stochastic cooling will be applied prior to rf-stacking and, e.g., electron cooling. In this paper, the authors present some special features of the stochastic cooling system which are due to the high charge states, the existence of a stack, and the fairly large frequency dispersion. These include Palmer cooling with adjustable cable lengths for high and low momentum signals in order to reduce unwanted mixing, and compensation of horizontal heating due to momentum kicks by suitable transverse kicks. Also, a method of cleaning the horizontal pick-up signal from momentum information is discussed