40 Years of Electron Cooling at CERN

For nearly 40 years electron cooling has been used extensively on the storage rings of the CERN accelerator complex for the accumulation of ions or for the improvement of beam quality for precision experiments. Since the first cooling experiments on ICE the coolers have evolved to incorporate the latest advances in electron cooling technology and many unique experiments have also been performed when the coolers are not used for everyday operation. The trapping of anti-hydrogen atoms and more recently lead-lead and proton-lead ion collisions in the LHC have been made possible thanks to cooling in the AD and cooling and accumulation of lead ions in the LEIR respectively. The next cooler to be built at CERN will be installed on ELENA and will operate at electron energies below 350 eV. Many challenges lie ahead in operating at such a low energy with minimum perturbation to the storage ring. The present AD cooler, which has already seen two re-incarnations, will also be replaced with a new state-of-the-art device operating at higher energies in order to improve the quality of the antiproton beam in this ring.