K Isomers in ~(254)No: Probing Single-Particle Energies and Pairing Strengths in the Heaviest Nuclei

摘要

We have identified two isomers in ~(254)No, built on two- and four-quasiparticle excitations, with quantum numbers K~π = 8~- and (14~+), as well as a low-energy 2-quasiparticle K~π = 3~+ state. The occurrence of isomers establishes that K is a good quantum number and therefore that the nucleus has an axial prolate shape. The 2-quasiparticle states probe the energies of the proton levels that govern the stability of superheavy nuclei, test 2-quasiparticle energies from theory, and thereby check their predictions of magic gaps.