The odd-$Z {}^{251}\mathrm{Md}$ nucleus was studied using combined $\gamma$-ray and conversion-electron in-beam spectroscopy. Besides the previously observed rotational band based on the $\left[521\right]1/2^{-}$ configuration, another rotational structure has been identified using $\gamma -\gamma$ coincidences. The use of electron spectroscopy allowed the rotational bands to be observed over a larger rotational frequency range. Using the transition intensities that depend on the gyromagnetic factor, a $\left[514\right]7/2^{-}$ single-particle configuration has been inferred for this band, i.e., the ground-state band. A physical background that dominates the electron spectrum with an intensity of $\simeq 60\%$ was well reproduced by simulating a set of unresolved excited bands. Moreover, a detailed analysis of the intensity profile as a function of the angular momentum provided a method for deriving the orbital gyromagnetic factor, namely $g_K=0.{69}_{-0.16}^{+0.19}$ for the ground-state band. The odd-$Z {}^{249}\mathrm{Md}$ was studied using $\gamma$-ray in-beam spectroscopy. Evidence for octupole correlations resulting from the mixing of the $\mathrm{\Delta }l=\mathrm{\Delta }j=3 \left[521\right]3/2^{-}$ and $\left[633\right]7/2^{+}$ Nilsson orbitals were found in both ${}^{249,251}\mathrm{Md}$. A surprising similarity of the ${}^{251}\mathrm{Md}$ ground-state band transition energies with those of the excited band of ${}^{255}\mathrm{Lr}$ has been discussed in terms of identical bands. Skyrme-Hartree-Fock-Bogoliubov calculations were performed to investigate the origin of the similarities between these bands.

• Received 23 July 2019
• Revised 27 May 2020
• Accepted 22 June 2020

DOI:https://doi.org/10.1103/PhysRevC.102.014307