1204.4139 (V. V. Simon et al.)

Penning-trap mass spectrometry of highly charged, neutron-rich Rb and Sr
isotopes in the vicinity of $A\approx100$    [PDF]

V. V. Simon, T. Brunner, U. Chowdhury, B. Eberhardt, S. Ettenauer, A. T. Gallant, E. Mané, M. C. Simon, P. Delheij, M. R. Pearson, G. Audi, G. Gwinner, D. Lunney, H. Schatz, J. Dilling

The neutron-rich mass region around $A\approx100$ 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 $^{94,97,98}$Rb and $^{94,97-99}$Sr have uncertainties of less than 4 keV and show deviations of up to 11$\sigma$ 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.

View original: http://arxiv.org/abs/1204.4139