Mass-selective operation with REXTRAP

At the radioactive ion-beam facility REX-ISOLDE more than 60 different types of radionuclide ions have been post-accelerated to energies up to 3.15 MeV/u within the last years. The transmission efficiency of the system has continually increased with gained operation experience. Apart from striving for the highest possible intensity, the beam purity is also of crucial importance for many experiments. For this reason isobaric contaminant suppression in the low energy stage of REX-ISOLDE has been investigated. Until now the Penning trap system REXTRAP was used solely as a device for bunching the incoming quasi-continuous radioactive ion-beam from ISOLDE and reducing the emittance for efficient injection into the REXEBIS charge breeder. The possibility of operating REXTRAP in a mass-resolving mode and injecting bunched beams from the recently installed radiofrequency quadrupole cooler and buncher ISCOOL has been studied in detail. Results related to transmission efficiency,achieved mass-resolving power, and limitations due to space-charge effects are presented.