Spherical And Deformed Structures In 189Pb

Gamma‐ray spectroscopy of high‐spin states of the neutron‐deficient nucleus 189Pb has been conducted with the 158Gd(36Ar,5n) and 164Er(29Si,4n) reactions. With the first of these, detection of evaporation residues and mass gating were used to unambiguously assign a number of prompt γ ray transitions to 189Pb. With the second reaction and a pulsed beams, an isomer with a mean life of 32 μsec was found and the decay scheme below it established. Although inconclusive, the available evidence favours identification of the isomer with the 332+ state of the v(i13/2)−3 configuration. The levels observed below the isomer can be identified with states involving three different structures: the neutron (i13/2)−3 multiplet in the spherical well; a prolate‐deformed band involving mixed i13/2 neutron orbitals; and a state with the oblate π(2p‐2h)0+ ⊗ v(i13/2)−1 configuration.