Penning-trap mass spectrometry of highly charged, neutron-rich Rb and Sr isotopes in the vicinity of A≈100

The neutron-rich mass region around A≈100 presents challenges for modeling the astrophysical r process because of rapid shape transitions. We report on mass measurements using the TITAN Penning trap at TRIUMF-ISAC to attain more reliable theoretical predictions of r-process nucleosynthesis paths in this region. A new approach using highly charged (q=15+) ions has been applied which considerably saves measurement time and preserves accuracy. New mass measurements of neutron-rich 94^,97^,98Rb and 94 ^,97^-99Sr have uncertainties of less than 4 keV and show deviations of up to 11σ when compared to previous measurements. An analysis using a parameterized r-process model is performed and shows that mass uncertainties for the A=90 abundance region are eliminated.