Accuracy tests of atomic mass measurements in a penning trap using externally produced highly charged ions

The SMILETRAP experimental set-up, a Penning trap mass spectrometer for highly charged ions, is described. Capture and observation of cyclotron frequencies of externally produced highly charged ions is demonstrated. Mass measurements utilizing different charge states and species to verify the consistency of the measurements are presented. A relative uncertainty <3 10−9 is attained in comparisons between highly charged 12C, 14N, 16O, 20Ne and singly charged H, H2 and H3 ions. The current limitations and future developments are discussed.