High-Spin Isomers, Residual Interactions And Octupole Correlations In The N=128 Isotones: ~(211)Bi, ~(212)Po and ~(213)At

摘要

Despite the fact that ~(208)Pb is probably the best example of a shell model nucleus, little is known about its high-spin states and those of its nearest neighbours, primarily because of the experimental difficulties involved in populating neutron-rich nuclei. The high-spin states formed from the valence orbitals are important since they provide the building blocks from which more complex configurations can be calculated. The same orbitals are involved in particle-octupole vibrational coupling which presumably evolves into octupole deformation in heavier nuclei. In this paper we present the results of recent measurements which have used a range of reaction techniques to access states in the N = 128 isotones, ~(211)Bi, ~(212)Po and ~(213)At. The results may contribute to the understanding of the structure of the τ = 65 s isomer in ~(212)Po. The new states identified include a J~π = 49/2~+ , τ = 65 μs isomer in ~(213)At which decays via an enhanced E3 transition whose strength is influenced by blocking.