Stochastic cooling at the ESR

Stochastic precooling at the ESR storage ring of GSI will be used mainly fo r experiments with stored radioactive fragment beams. They arrive from the fragment separator with momentum spreads and emittances for which electron cooling is too slow. The installation of components at the ESR is now compl ete and first commissioning experiments have been performed. Both longitudi nal and transverse stochastic cooling have been demonstrated. The paper giv es a short account of the system architecture, and of the response of quart er-wave plates and superelectrodes at intermediate energies. The preparatio n of fragment beams suitable for subsequent electron cooling is discussed f or the case that a mixture of different ion species is present in the coole r ring. Results of commissioning and future prospects are presented. (C) 20 00 Elsevier Science B.V. All rights reserved.