COLETTE: A linear Paul-trap beam cooler for the on-line mass spectrometer MISTRAL

A segmented, radiofrequency quadrupole mass filter COLETTE (Cooler for Emittance Elimination) was designed for cooling continuous radioactive beams for injection into the transmission spectrometer MISTRAL at CERN–ISOLDE. A description of the design of COLETTE is given, along with details of performance including measured emittances of less than 8πmmmrad with 20 keV beams from the test bench SIDONIE in Orsay. On-line results with stable and short-lived radionuclide beams from ISOLDE are also presented.