γ-Ray spectroscopy at the limits: First observation of rotational bands in Lr255

The rotational band structure of Lr255 has been investigated using advanced in-beam γ-ray spectroscopic techniques. To date, Lr255 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 α 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. © 2009 The American Physical Society.