Evidence for the Existence of the [Formula presented] Deformed Band in Mirror Nuclei [Formula presented] and [Formula presented]

After 50 years of its prediction, the highest-lying [Formula presented] orbit among the six Nilsson single-particle orbits originating from the [Formula presented] shells in prolately deformed nuclei and the rotational band on this orbit were identified. The band members were observed in [Formula presented] at excitation energies of 6–7.5 MeV in a high-resolution [Formula presented] charge-exchange reaction at [Formula presented] having a strong selectivity for Gamow-Teller transitions. In the comparison with the analogous [Formula presented] transitions in [Formula presented], the [Formula presented] bandhead state and the excited [Formula presented] and [Formula presented] members were clearly assigned.