An extended decay scheme for 128 Xe has been constructed by using data from the 124 Sn( 9 Be, 5n) 128 Xe reaction at a beam energy of 58 MeV. Bands have been identified as being built on several intrinsic states, including a proposed 9/2 − [514] ⊗ 1/2 + [400] two-quasineutron configuration that forms the K π = 5 − intrinsic state at 2228 keV, and on a previously assigned K π = 8 − intrinsic state at 2786 keV. A half-life of 73(3) ns has been measured for the latter. Theoretical calculations have been performed by using the configuration-constrained blocking method based on a nonaxial Woods-Saxon potential. Large γ deformation and γ softness are predicted for the ground state and the K π = 5 − intrinsic state, whereas a nearly axially symmetric shape is predicted for the K π = 8 − two-quasiparticle configuration. The low value of the hindrance factor for the E1 transition depopulating the K π = 8 − intrinsic state is discussed in the context of analogous transitions in neighbouring N = 74 isotones.

The structure of the deformed, doubly odd nuclide 180 Re has been studied by γ -ray and conversion-electron spectroscopy using the 174 Yb( 11 B,5n) reaction with a pulsed 71 MeV beam of 11 B ions. Several of the previously known intrinsic states have been given revised spin and parity assignments. Rotational bands are observed with K π = (4 + ), (5 − ), (7 + ), 8 + , 9 − , 13 + , 14 − , 15 − , 16 + , 21 − , and (22 + ). Among these, a four-quasiparticle t band is identified, which is already energetically favored at its bandhead compared to the corresponding two-quasiparticle band; and two six-quasiparticle bands are identified and associated with a τ = 13 µs isomer. The observed structures, including g factors and alignments, are interpreted with the aid of Nilsson-plus-BCS calculations and configuration-constrained potential energy surface calculations. Reduced-hindrance values are obtained for K-forbidden transitions, illustrating the important role of the K quantum number for near-yrast isomers.

No abstract