High spin states in ${}^{140}\mathrm{Eu}$ were populated following the reaction ${}^{92}\mathrm{Mo}\left({}^{51}\mathrm{V},2pn\right)$ at a beam energy of $205\text{MeV}$ by the ESTU accelerator at the Wright Nuclear Structure Laboratory, Yale University. A total of 5 bands and 69 transitions were assigned to ${}^{140}\mathrm{Eu}$. The assignments were based on $K_{\alpha }$ x-ray coincidences and on excitation function measurements. $\gamma \text{−}\gamma$ and $\gamma \text{−}\gamma \text{−}\gamma$ coincidence matrices were created. Directional correlation of oriented states analysis, angular distributions, and Compton asymmetry measurements were performed and $B\left(M1\right)∕B\left(E2\right)$ branching ratios were extracted. The band assignments and structures are discussed in terms of the rotational model and interpreted following a series of cranked shell model and total Routhian surface calculations. In particular, two pairs of bands, one pair based on the $\pi h_{11∕2}\otimes \nu h_{11∕2}$ configuration, the other based on the $\pi (g_{7∕2},d_{5∕2})\otimes \nu h_{11∕2}$ configuration, are identified. These bands show some features expected of either chiral partners or shape coexistence, based on triaxial shapes with $\gamma \sim \pm 25°$. Further measurements are required to distinguish between these two possibilities.

• Received 25 July 2003

DOI:https://doi.org/10.1103/PhysRevC.68.054310