Decay ofYb178and the Isomers ofLu178

The neutron-rich radionuclide ${}_{}{}^{178}{}_{}{}^{}\mathrm{Yb}$ has been produced by the ($t,p$) reaction in the bombardment of enriched ${}_{}{}^{176}{}_{}{}^{}\mathrm{Yb}$ with 12-MeV tritons. The products of the bombardment were radiochemically separated by an ion-exchange column procedure. The decay of 74 ± 3-min ${}_{}{}^{178}{}_{}{}^{}\mathrm{Yb}$ includes a 42.4-keV $\gamma$ transition as well as 348.4- and 390.8-keV transitions which deexcite a 390.8-keV ${}_{}{}^{178}{}_{}{}^{}\mathrm{Lu}$ level that is populated from ${}_{}{}^{178}{}_{}{}^{}\mathrm{Yb}$ by a 0.25 ± 0.03-MeV $\beta$ transition. The total disintegration energy of ${}_{}{}^{178}{}_{}{}^{}\mathrm{Yb}$ is therefore 0.64 ± 0.03 MeV. The 28.4 ± 0.2-min-${}_{}{}^{178}{}_{}{}^{}\mathrm{Lu}$ ground state, which is the sole daughter of ${}_{}{}^{178}{}_{}{}^{}\mathrm{Yb}$, decays strongly to the $0^{+}$ and $2^{+}$ members of the ${}_{}{}^{178}{}_{}{}^{}\mathrm{Hf}$ ground-state band and also to ${}_{}{}^{178}{}_{}{}^{}\mathrm{Hf}$ excited states at 1260.0, 1309.9, 1323.0, 1362.4, 1434.0, 1443.8, 1496.1, 1513.7, 1561.2, 1566.8, 1772.0, and 1818 keV. A 22.7 ± 0.4-min high-spin isomer of ${}_{}{}^{178}{}_{}{}^{}\mathrm{Lu}$ was produced in the bombardments only via the ($t,n$) reaction. This isomer undergoes $\beta$ decay to 1147-(86%) and 1478-(14%) keV states in ${}_{}{}^{178}{}_{}{}^{}\mathrm{Hf}$. No isomeric transition in ${}_{}{}^{178}{}_{}{}^{}\mathrm{Lu}$ was observed.