Mass determination of light ions in a Penning trap by time-of-flight detection of ion resonances

We describe an experimental setup to determine the cyclotron frequencies of ions confined in a Penning trap by resonant excitation of the ions eigenfrequencies and a time-of-flight detection of the resonances. Systematic shifts from trap- and B -field imperfections are discussed and methods to minimize those effects in our experiment are presented. Results on the mass ratio for 4 He/D 2 and 3 He/H 2 demonstrate the experimentally obtained precision in the ppb range, which might be further improved by modification of our apparatus.