Structure of the semi-decoupled π 1/2[411] band in odd proton nucleus 169Ta

High spin states of the odd proton-nucleus Ta-169 have been populated in the reaction Gd-155(F-19, 5n) with beam energies of 97MeV. Rotational band based on d(3/2) proton 112[411] Nilsson state has been pushed up to 39/2+ in the alpha = 1/2 decay sequence. Its signature partner, the alpha = -1/2 decay sequence with four link transitions has been established and 1/2[411] band in Ta-169 was reassigned to be a semi-decoupled band. The systematics of the signature splitting in the K = 1/2 bands in the rear-earth region and the accidental degeneracy conclusion given by the angular projection shell model were discussed.