New levels have been established above the 861-keV, $9/2^{+}$ isomeric state in ${}^{61}\mathrm{Fe}$. The observations can be reproduced satisfactorily by shell model calculations, but only after a significant lowering of the $\nu g_{9/2}$ single-particle energy with respect to the value determined empirically from levels outside a ${}^{48}\mathrm{Ca}$ core. The results are also described well within the scope of the particle-triaxial-rotor model assuming a deformation ${\beta }_2~0.24$. The present findings, together with the recently measured magnetic and quadrupole moments of this state, point toward a structure possibly associated with a prolate shape.

• Received 19 November 2007

DOI:https://doi.org/10.1103/PhysRevC.77.044314