Rotational bands inCe133

Abstract

Several rotational bands built on one- and three-quasiparticle configurations have been populated in the odd-neutron ${}_{}{}^{133}{}_{}{}^{}\mathrm{Ce}$ nucleus following the ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sn}$ ${(}^{18}$O,4n) reaction. Both signature components of bands built on the [514]${(9/2\mathrm{}}^{\mathrm{-}}$ and [400]${(1/2\mathrm{}}^{+}$ orbitals were observed. At low spins, the yrast band, based on a neutron from the upper $h_{11/2}$ midshell, shows a large signature splitting (>100 keV), indicating a significant triaxial deformation (γ∼-20°). Four ΔI=1 bands were observed at higher spins based on three-quasiparticle configurations. Strong M1 transitions and the lack of signature splitting imply that these bands are near prolate (γ∼0°) and thus contain one or more aligned $h_{11/2}$ protons from the lower midshell. In two of these bands, weak E2 crossover transitions were seen; measured B(M1;I→I-1)/B(E2;I→I-2) ratios were used to assign configurations. In addition, a ΔI=2 band with an enhanced moment of inertia was observed most probably built on the prolate ν$i_{13/2}$⊗[π$h_{11/2}$ ${]}^2$ configuration. Only one signature component of this configuration was seen because of the maximal signature splitting of the β-driving $i_{13/2}$ neutron orbital (Ω=(1/2).