Characterization of the shape-staggering effect in mercury nuclei

Nature Physics paper that finally maps the famous odd-even shape staggering in mercury down to ¹⁷⁷Hg and shows that the effect ends at ¹⁸¹Hg.

An ISOLDE campaign combining resonance laser ionization, nuclear spectroscopy, and mass spectrometry. Monte Carlo shell-model calculations with a very large valence space identify the orbitals that drive the shape change.

Mercury is still the textbook case of a nucleus that changes shape when a single neutron is added or removed. Pinning the endpoint and the orbitals (proton h_{9/2} and neutron i_{13/2}) turned a 1970s puzzle into a microscopic mechanism.