New data for the 7-min activity of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Lu}$ are presented and combined with recent data on the levels of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Yb}$ to assign the following levels (energies and spins) in ${}_{}{}^{168}{}_{}{}^{}\mathrm{Yb}$ populated by the decay of 7-min ${}_{}{}^{168}{}_{}{}^{}\mathrm{Lu}$: 87.5 keV, 2+0 (ground-state rotational); 986 keV, 2+2 ($\gamma$-vibrational); 1233 keV, 2+0 ($\beta$-vibrational); 1410 keV, (1-0?, octupole vibrational?); 1550 keV (?); 2002 keV, 2±; and 2127 keV, 1±, or 2195 keV, 2±. The spin of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Lu}$ is probably 1- or 2+. The 2-h activity of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Lu}$ may also be created by the 6-MeV proton bombardment of ${}_{}{}^{168}{}_{}{}^{}\mathrm{Yb}$. The upper limit for positrons in the 7-min ${}_{}{}^{168}{}_{}{}^{}\mathrm{Lu}$ decay can be 20 or 30%, rather than the originally reported 1%.

• Received 30 September 1968

DOI:https://doi.org/10.1103/PhysRev.178.1949