Deceleration and cooling of heavy ion beams: The COLETTE project

An ion beam cooler has been constructed to adapt the ISOLDE rare isotope beam emittance to the acceptance of the mass spectrometer MISTRAL, CERN. In a test experiment a Na+-beam was extracted out of the gas filled, linear Paul Trap with an emittance of 8π mm mrad at 6 keV. Near 100% transmission through a new electrostatic deceleration system was measured for a 30 keV He+-beam which was decelerated to a final energy of 10 eV. A method to determine the longitudinal energy spread of the decelerated beam as function of its initial emittance is discussed.