New experimental information has been obtained on the μs isomeric cascade in the very neutron-rich ${}^{136}\mathrm{Sb}$ using γ-ray and conversion-electron spectroscopy at the Lohengrin mass spectrometer of the Institut Laue-Langevin. Two new transitions have been observed and their multipolarities determined, resolving the question of the origin of the isomerism. The new level scheme is in good agreement with predictions of a realistic shell-model calculation. The isomeric state is tentatively assigned a spin and parity of $6^{-}$ and a proposed $\pi g_{7/2}\nu (f_{7/2}){}^3$ dominant configuration.

• Received 26 June 2007

DOI:https://doi.org/10.1103/PhysRevC.76.041303