Electron and stochastic cooling at COSY

The synchrotron and storage ring COSY delivers proton beams with momenta be tween 300 and 3500 MeV/c for internal and external experiments. It is opera ting both with electron and stochastic cooling. The electron cooling is use d mainly at the injection energy with 22 keV electrons to increase the inte nsity of the polarised proton beam with a combined cooling stacking injecti on. In addition, the electron-cooled proton beam is used for diagnostic pur poses of machine parameters. The stochastic cooling for COSY is working in the proton momentum range between 1.5 and 3.5 GeV/c and is up to now only u sed for equilibrium experiments with thin internal targets and long flat to p times. The longitudinal stochastic cooling system is extended by a fast f requency variable optical notchfilter to make use of a supercycle in COSY w ith from cycle to cycle varying flat top energies. The results of the elect ron cooling and stacking injection as well as the good results of the optic al notchfilter for the stochastic cooling will be presented. (C) 2000 Elsev ier Science B.V. All rights reserved.