High-spin states in the odd-odd ${}^{172}\mathrm{Re}$ have been investigated via the ${}^{149}\mathrm{Sm}({}^{27}\mathrm{Al},4n\gamma ){}^{172}\mathrm{Re}$ reaction through excitation functions, $x\text{−}\gamma$ and $\gamma \text{−}\gamma$ coincidence measurements. A level scheme consisting of three rotational bands has been identified for the first time extending the high-spin studies of $A\sim 160$ odd-odd nuclei to the currently lightest rhenium isotope. The three bands have been assigned to be built on the $\pi h_{11∕2}\otimes \nu i_{13∕2}$, $\pi h_{9∕2}\otimes \nu i_{13∕2}$, and $\pi 1∕2^{-}\left[541\right]\otimes \nu 1∕2^{-}\left[521\right]$ configurations according to their rotational properties in quasiparticle alignments, signature splitting, in-band $B\left(M1\right)∕B\left(E2\right)$ ratios, level spacing systematics, band crossing frequencies, as well as the existing knowledge in neighboring nuclei. Low-spin signature inversion has been confirmed in the first two bands due to the observation of signature crossing at high-spin states. The general features of inversion phenomenon in the semidecoupled bands are presented and discussed with reference to theoretical calculations of two quasiparticle plus rotor model including $p\text{−}n$ interactions.

• Received 6 March 2003

DOI:https://doi.org/10.1103/PhysRevC.68.054313