In this paper we investigate the rotational band built upon a two-quasiparticle $8^{-}$ isomeric state of ${}^{252}$No up to spin $I^{\pi }$ $=$ ${22}^{-}$. The excited states of the band were populated with the ${}^{206}$Pb(${}^{48}\text{Ca},2n$) fusion-evaporation reaction. An unambiguous assignment of the structure of the $8^{-}$ isomer as a $7/2^{+}{\left[624\right]}_{\nu }\otimes 9/2^{-}{\left[734\right]}_{\nu }$ configuration has been made on the basis of purely experimental data. Comparisons with triaxial self-consistent Hartree-Fock-Bogoliubov calculations using the D1S force and breaking time-reversal as well as $z$-signature symmetries are performed. These predictions are in agreement with present measurements. Mean-field calculations extended to similar states in ${}^{250}$Fm support the interpretation of the same two-neutron quasiparticle structure as the bandhead in both $N=150$ isotones.

• Received 3 April 2012

DOI:https://doi.org/10.1103/PhysRevC.86.044318