New mass measurement of Li6 and ppb-level systematic studies of the Penning trap mass spectrometer TITAN

The frequency ratio of Li6 to Li7 was measured using the TITAN Penning trap mass spectrometer. This measurement resolves a 16-ppb discrepancy between the Li6 mass of 6.015 122 795(16) u from the Atomic Mass Evaluation 2003 (AME03), which is based on a measurement by JILATRAP, and the more recent measurement of 6.015 122 890(40) u by SMILETRAP. Our measurement agrees with SMILETRAP and a more precise mass value for Li6 of 6.015 122 889(26) u is presented along with systematic evaluations of the measurement uncertainties. This result makes Li6 a solid anchor point for future mass measurements on highly charged ions with m/q~6.