The level structures of the light lead nuclei ${}_{}{}^{195}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{197}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{199}{}_{}{}^{}\mathrm{Pb}$, and ${}_{}{}^{201}{}_{}{}^{}\mathrm{Pb}$ have been studied by in-beam $\gamma$-ray spectroscopy in bombardments of isotopically enriched HgO targets with ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ ions. The measurements included $\gamma$-ray singles, comprehensive ($\gamma \gamma t$) coincidences, half-life determinations, and $\gamma$-ray angular distributions. High-spin level spectra above previously known ${13/2}^{+}$ isomers are reported for the four nuclei, and are interpreted in terms of the weak coupling of an $i_{\frac{13}{2}}$ neutron hole to established states of the adjacent even-$A$ core nuclei.

NUCLEAR REACTIONS ${}_{}{}^{200,198}{}_{}{}^{}\mathrm{Hg}(\alpha ,3n)$, $E=35\mathrm{}-45$ MeV, ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}({}_{}{}^3{}_{}{}^{}\mathrm{He},4n)$, $E=38\mathrm{}$ MeV, ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}({}_{}{}^3{}_{}{}^{}\mathrm{He},6n)$, ${}_{}{}^{199}{}_{}{}^{}\mathrm{Hg}({}_{}{}^3{}_{}{}^{}\mathrm{He},7n)$, $E=74\mathrm{}$ MeV; measured $E_{\gamma }$, $I_{\gamma }\left(\theta \right)$, $\gamma -\gamma$ coin, $\gamma -t$ relationships; ${}_{}{}^{195,197,199,201}{}_{}{}^{}\mathrm{Pb}$ deduced high-spin levels, $J$, $\pi$, $T_{\frac{1}{2}}$.

• Received 21 November 1980

DOI:https://doi.org/10.1103/PhysRevC.23.1446