The rotational band structure of ${}^{255}\mathrm{Lr}$ has been investigated using advanced in-beam $\gamma$-ray spectroscopic techniques. To date, ${}^{255}\mathrm{Lr}$ is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the $1/2^{-}[521]$ and $7/2^{-}[514]$ Nilsson states, consistent with assignments from recently obtained $\alpha$ decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.

• Received 14 November 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.212501