Band crossings in theγ-soft nucleusNd136

High-spin states have been populated in ${}_{}{}^{136}{}_{}{}^{}\mathrm{Nd}$ using the ${}_{}{}^{116}{}_{}{}^{}\mathrm{Cd}$ ${(}^{24}$Mg,4nγ${)\mathrm{}}^{136}$Nd reaction. Several rotational bands have been observed based on two- and four-quasiparticle configurations. The ground-state band backbends sharply at a frequency ħω=0.34 MeV due to the alignment of a pair of $h_{11/2}$ protons. Both signatures of a negative parity side band based on a π$h_{11/2}$⊗π$g_{7/2}$ configuration were observed to backbend at a frequency ħω=0.44 MeV, again due to the alignment of a pair of $h_{11/2}$ protons. All these bands are prolate because of the stabilizing influence of the $h_{11/2}$ quasiprotons on the γ-soft core. In addition to the $h_{11/2}$ proton alignment in the ground-state band, a rotational band is observed built on a second ${10}^{+}$ state, which involves the alignment of a pair of $h_{11/2}$ neutrons. An alignment of neutrons from the upper $h_{11/2}$ midshell drives the nucleus towards a collectively rotating oblate (γ=-60°) shape. Both signatures of a band based on a ν$h_{11/2}$⊗ν$g_{7/2}$ configuration were observed, also possibly oblate. The observation of both neutron and proton low-frequency alignments is consistent with cranked-shell model calculations and theoretical estimates of the prolate-oblate energy difference for this nucleus.