Exploration for Astromers near $^{132}$Sn with the Canadian Penning Trap

A. A. Valverde, S. Cupp, A. Gross, B. Liu, M. Mumpower

Submitted submitted (2025)

Nuclear isomers can have significant impacts on astrophysical nucleosynthesis processes, with recent efforts demonstrating that the population of isomeric states with different half-lives may require separate treatment in reaction networks to accurately capture the differences in heating or in identifiable electromagnetic signals. Several potential so-called ``astromers'' in tin and antimony isotopes near doubly-magic 132Sn were identified and direct mass measurements of their ground and isomeric states were performed with the Canadian Penning Trap at Argonne National Laboratory's CARIBU facility, and their impact on astrophysical reaction rates and in reaction networks calculated. It was found that 129g,mSn, with measured mass excesses of −80593.2(25) keV and −80557.4(25) keV, respectively, and an excitation energy of 35.8(35) keV, behaves as an astromer during neutron capture in the i-process and in the r-process.