High-accuracy mass measurements of neutron-rich Kr isotopes

Abstract

The atomic masses of the neutron-rich krypton isotopes $^{84,86\ensuremath{-}95}\mathrm{Kr}$ 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 $^{94}\mathrm{Kr}$ and $^{95}\mathrm{Kr}$ were measured for the first time. The masses of the radioactive nuclides $^{89}\mathrm{Kr}$ and $^{91}\mathrm{Kr}$ 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.