We report first precision mass measurements of the $1/2^{-}$ isomeric and $9/2^{+}$ ground states of ${}^{101}\mathrm{In}$. The determined isomeric excitation energy continues a smooth trend of odd-$A$ indium isotopes up to the immediate vicinity of $N=50$ magic number. This trend can be confirmed by dedicated shell-model calculations only if the neutron configuration mixing is considered. We find that the single-particle energies are different for different states of the same isotope. The presented configuration-dependent shell evolution, type-II shell evolution, in odd-$A$ nuclei is discussed for the first time. Our results will facilitate future studies of single-particle neutron states.

• Received 7 July 2019

DOI:https://doi.org/10.1103/PhysRevC.100.051303