Precision mass measurement of lightweight self-conjugate nucleus 80Zr

Protons and neutrons in the atomic nucleus move shells analogous to electronic shell structures of atoms. The nuclear structure varies as a result changes mean field with number N protons Z, these variations can be probed by measuring mass differences between nuclei. = Z 40 self-conjugate 80Zr is particular interest, its proton neutron are expected very similar, ground state highly deformed. Here we provide evidence for existence deformed double-shell closure through high-precision Penning trap measurements 80–83Zr. Our values show that substantially lighter, thus more strongly bound than predicted. This attributed at large Wigner energy. A statistical Bayesian-model mixing analysis employing several global models demonstrates difficulties reproducing observed anomaly using current theory. High-precision exotic zirconium nuclei reported, reveal 80Zr, which previously thought.