Structure of three-quasiparticle isomers in Ho169 and Tm171

A three-quasiparticle isomer with τ=170(8) μs and Kπ= (19/2 +) has been identified in the neutron-rich isotope Ho169. The isomer decays with K-forbidden transitions to members of a band associated with the 7/2-[523] proton configuration, whose structure is characterized through analysis of the in-band γ-ray branching ratios. In the isotone Tm171, the rotational band based on the known 19/2+, three-quasiparticle isomer has also been observed. Alternative one-proton two-neutron configurations for the isomer in Ho169 are discussed in terms of multiquasiparticle calculations and through a comparison with the structures observed in Tm171.