A multi-reflection time-of-flight mass separator for isobaric purification of radioactive ion beams

A multi-reflection time-of-flight mass separator (MR-ToF-MS) for the enhancement of the performance of the Penning-trap mass spectrometer ISOLTRAP at the on-line isotope separator ISOLDE/CERN has been built and investigated at an off-line test facility. The MR-ToF-MS consists of two ion-optical mirrors between which oscillating ions are separated according to their different mass-over-charge ratios m/q. Flight paths of several hundreds of meters are folded to an apparatus length of less than one meter. Preliminary tests resulted in a mass-resolving power of up to m/Δm ≈ 80,000, and the separation was demonstrated for the isobaric ions CO +  and N2+. The MR-ToF-MS will support the existing purification methods of ISOLTRAP and will extend the access to nuclides produced with high isobaric contamination yields at the ISOLDE facility.