The locations of 70 energy levels in ${}_{}{}^{170}{}_{}{}^{}\mathrm{Yb}$ were deduced from Compton-suppressed $\gamma$-ray singles, three-crystal $\gamma$-ray pair, conversion-electron, and Ge(Li)-Ge(Li) $\gamma -\gamma$ coincidence measurements on the electron-capture-${\beta }^{+}$ decay of ${}_{}{}^{170}{}_{}{}^{}\mathrm{Lu}$. Both chemically separated and isotopically separated sources of ${}_{}{}^{170}{}_{}{}^{}\mathrm{Lu}$ were used in collecting the data. A total of 550 $\gamma$-ray transitions have been observed in the ${}_{}{}^{170}{}_{}{}^{}\mathrm{Lu}$ decay spectrum, 220 of which are definitely assigned to the ${}_{}{}^{170}{}_{}{}^{}\mathrm{Yb}$ level scheme from 112 coincidence spectra. These definitive transitions account for 93% of the total observed $\gamma$-ray intensity. An additional 118 $\gamma$-ray transitions were placed on the basis of excited-state energy differences. Eight $E0\mathrm{}$ transitions were observed in the conversion-electron data. Each of four excited $0^{+}$ states identified has less than 1% $\beta$ decay feeding from the $0^{+}$ parent. Spin and parity assignments are proposed for 46 levels in addition to the ground-state rotational band members. The ${}_{}{}^{170}{}_{}{}^{}\mathrm{Yb}$ level structure is compared with available theoretical calculations, and a preliminary interpretation of several features of the decay scheme is presented.

• Received 24 November 1971

DOI:https://doi.org/10.1103/PhysRevC.6.1040