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

TL;DR

This study uses advanced Penning trap mass spectrometry with highly charged ions to precisely measure neutron-rich Rb and Sr isotopes near A=100, improving models of astrophysical r-process nucleosynthesis.

Contribution

It introduces a new highly charged ion measurement technique that enhances accuracy and efficiency in mass measurements of neutron-rich isotopes relevant to the r-process.

Findings

Mass uncertainties for key isotopes are reduced to below 4 keV.

Deviations from previous measurements reach up to 11 sigma.

Mass measurements help eliminate uncertainties in the A=90 abundance region.

Abstract

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.