Multi-quasiparticle excitation: Extending shape coexistence in A ~ 190 neutron-deficient nuclei

Multi-quasiparticle high-K states in neutron-deficient mercury, lead, and polonium isotopes have been investigated systematically by means of configuration-constrained potential-energy-surface calculations. An abundance of high-K states is predicted with both prolate and oblate shapes, which extends the shape coexistence of the mass region. Well-deformed shapes provide good conditions for the formation of isomers, as exemplified in ¹⁸⁸Pb. Of particular interest is the prediction of low-lying 10^- states in polonium isotopes, which indicate long-lived isomers.