Nuclear Mass Measurements Map the Structure of Atomic Nuclei and Accreting Neutron Stars

Abstract

We present mass excesses (ME) of neutron-rich isotopes of Ar through Fe, obtained via TOF-$B\rho$ mass spectrometry at the National Superconducting Cyclotron Laboratory. Our new results have significantly reduced systematic uncertainties relative to a prior analysis, enabling the first determination of ME for ${}^{58,59}\mathrm{Ti}$, ${}^{62}\mathrm{V}$, ${}^{65}\mathrm{Cr}$, ${}^{67,68}\mathrm{Mn}$, and ${}^{69,70}\mathrm{Fe}$. Our results show the $N=34$ subshell weaken at Sc and vanish at Ti, along with the absence of an $N=40$ subshell at Mn. This leads to a cooler accreted neutron star crust, highlighting the connection between the structure of nuclei and neutron stars.

Comments: Accepted for publication as a Rapid Communication in Physical Review C