High-accuracy mass measurements of neutron-rich Kr isotopes

The atomic masses of the neutron-rich krypton isotopes Kr-84,Kr-86-95 have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes Kr-94 and Kr-95 were measured for the first time. The masses of the radioactive nuclides Kr-89 and Kr-91 disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.