Bingchen He (UTK): Shell evolution beyond 132Sn: Is 140Sn doubly magic?

Monday Aug 24, 2026, 1:50 PM → 2:40 PM US/Eastern

604 (Nielsen)

Whether Sn140 exhibits a neutron shell closure at (N=90) remains theoretically unsettled. We investigate its structure using the chiral 1.8/2.0 (EM) interaction with coupled-cluster and in-medium similarity renormalization group methods. After validating our framework against the low-lying spectrum of Sn133, we compute the first 2+ state in Sn140. Both methods predict a low excitation of energy, below 1.5 MeV. The resulting energy is small, and this contradicts the assumption of the neutron N=90 shell closure.