Interplay Between K-Isomerism and γ -Softness in 128Xe

A partial decay scheme for 128Xe is presented. The Kπ = 8- state is isomeric with a half-life of 73(5) ns. Theoretical calculations have been performed using the configuration constrained blocking method based on a non-axial Woods-Saxon potential. Large γ-deformation and γ-softness have been predicted for the ground state. The strong shape-driving effect of the Kπ = 8- state results in a much smaller value of γ for this configuration. This may partly explain the isomerism, despite the γ-softness. Measured hindrance factors are discussed in the context of the γ -softness of this nucleus. (author)