A pulsed-beam ${}_{}{}^{202}{}_{}{}^{}\mathrm{Hg}(\alpha ,3n\gamma )$ experiment has revealed a 0.48-s ${}_{}{}^{203}{}_{}{}^{}\mathrm{Pb}$ isomer, which deexcites through high-spin positive parity levels to the known ${13/2}^{+}$ state at 825 keV. Comprehensive ($\gamma \gamma t$) coincidence measurements have established the complete isomeric decay scheme, and key transition multipolarities have been deduced from prompt $\gamma$-ray angular distribution data and from intensity balance requirements. The results clearly manifest a close structural relationship between the high-spin levels built on the ${}_{}{}^{203}{}_{}{}^{}\mathrm{Pb}$ ${13/2}^{+}$ isomer and previously known states of the ${}_{}{}^{204}{}_{}{}^{}\mathrm{Pb}$ core nucleus. The 0.48-s isomeric state is assigned $J^{\pi }={\frac{29}{2}}^{-}$, with the dominant neutron hole configuration ${\left(p_{\frac{1}{2}}^{}{}_{}{}^{-2\mathrm{}}\right)}_{0}f_{\frac{5}{2}}^{}{}_{}{}^{-1\mathrm{}}{\left(i_{\frac{13}{2}}^{}{}_{}{}^{-2\mathrm{}}\right)}_{12}$, and the high-spin positive parity levels are interpreted as members of core hole multiplets of the type $i_{\frac{13}{2}}^{}{}_{}{}^{-1\mathrm{}}\times 2^{+}$ and $i_{\frac{13}{2}}^{}{}_{}{}^{-1\mathrm{}}\times 4^{+}$.

NUCLEAR REACTIONS ${}_{}{}^{202}{}_{}{}^{}\mathrm{Hg}(\alpha ,3n\gamma )$, $E=38.2\mathrm{}$ MeV; measured $E_{\gamma }$, $I_{\gamma }\left(\Theta \right)$, $\gamma -\gamma$ coin, $\gamma -t$ relationships; ${}_{}{}^{203}{}_{}{}^{}\mathrm{Pb}$ deduced high spin levels, $J$, $\pi$, $T_{\frac{1}{2}}$.

• Received 22 August 1977

DOI:https://doi.org/10.1103/PhysRevC.16.2159