High-$K$ multi-quasiparticle states and rotational bands in ${}_{103}^{255}\mathrm{Lr}$

Two isomeric states have been identified in ${}^{255}\mathrm{Lr}$. The decay of the isomers populates rotational structures. Comparison with macroscopic-microscopic calculations suggests that the lowest observed sequence is built upon the $[624]9/2^{+}$ Nilsson state. However, microscopic cranked relativistic Hartree-Bogoliubov (CRHB) calculations do not reproduce the moment of inertia within typical accuracy. This is a clear challenge to theories describing the heaviest elements.

Figure 1

(a) Electron-burst sum energy for all r-$e$ events. The insert shows the time difference between each electron burst and the associated recoil. (b) $\gamma$ rays in coincidence with the electron bursts. The insert shows an expansion of the low-energy part of the spectrum. Asterisks indicate known Lr X rays.

Figure 2

Level scheme for ${}^{255}\mathrm{Lr}$. Energies are in keV. Suggested spins and parities are indicated in parentheses. The two isomeric states are indicated by thicker lines.

Figure 3

Experimental (energies in keV) and calculated (with Nilsson labels) one-quasiproton states in ${}^{255}\mathrm{Lr}$. The notations MM, HFB-SLy4, and CRHB $+$ NL1 label the respective calculations. The inset shows kinematic moments of inertia from CRHB calculations (solid lines) and experiment (open circles).