We report precision mass measurements of $^{74-76}$Sr performed with the TITAN Multiple-Reflection Time-of-Flight Mass Spectrometer. This marks a first time mass measurement of $^{74}$Sr and gives increased mass precision to both $^{75}$Sr and $^{76}$Sr which were previously measured using storage ring and Penning trap methods, respectively. This completes the A = 74, T = 1 isospin triplet and gives increased precision to the A = 75, T = 1/2 isospin doublet which are both the heaviest experimentally evaluated triplets and doublets to date. The new data allow us to evaluate coefficients of the isobaric multiplet mass equation for the first time at A = 74, and with increased precision at A = 75. With increased precision of 75Sr, we confirm the recent measurement reported by CSRe which was used to remove a staggering anomaly in the doublets. New ab initio valence-space in-medium similarity renormalization group calculations of the T = 1 triplet are presented at A = 74. We also investigate the impact of the new mass data on the reaction flow of the rapid proton capture process in type I x-ray bursts using a single-zone model.

Strange hadrons have been suggested as sensitive probes of the properties of the nuclear matter created in heavy-ion collisions. At few-GeV collision energies, the formed medium is baryon-rich due to baryon stopping effect. In these proceedings, the recent results on strange hadron production in Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 3.2, 3.5, 3.9 and 4.5 GeV with the fixed-target mode from the STAR Beam Energy Scan phase-II program are presented. The transverse momentum spectra, rapidity density distributions, excitation function and centrality dependence of strange hadrons ($\rm{K}^0_S,~\Lambda, ~\Xi^-$) are shown. These results are compared with those from higher collision energies and physics implications are discussed by comparing to the transport model calculations.