Cooled heavy ions in the storage ring ESR

The ESR storage ring is equipped with stochastic and electron cooling. Electron cooling is the standard method for most internal experiments with stored heavy ion or rare isotope beams covering a wide energy range. Stochastic cooling is mainly used as a pre-cooling method for hot beams. The combination of both methods allows a considerable reduction of the total cooling time, which is particularly important for experiments with short-lived radioactive ions. At low beam intensity electron cooling results in extremely cold beams which show clear evidence for ordering in a linear string-like structure. A special ion optical mode of the ESR reduces the transition energy to gamma(t) = 1.37, thus the behavior of cooled beams above transition energy can be studied. Laser cooling of a C3+ beam of velocity beta = 0.47 is being developed employing electron cooling as a pre-cooling method.