In-beam measurements of internal-conversion electrons and $\gamma$ rays from ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}(\alpha ,2n){}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$ are reported. The most recent yrast level scheme, used by several other groups, is found to be in error since the 480-ns state is not primarily deexcited by an 84-keV transition. This transition must instead be ≲ 43 keV. The primary deexcitation of the 158-ns state must be ≲ 50 keV. The 778-keV high-spin transition is measured as $E1\mathrm{}$. The multipole orders of the transitions in the 245→420→462→1026 keV cascade are measured as $E2\mathrm{}$, $E1\mathrm{}$, $E2\mathrm{}$, and $E2\mathrm{}$, respectively.

NUCLEAR REACTIONS ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}(\alpha ,2n){}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$, $E_{\alpha }=30\mathrm{}$ MeV; measured 30-1600-keV internal conversion electron spectra and $\gamma$ spectra in eight time bands in beam. Deduced levels $J$, $\Pi$, ICC. Si(Li) and Ge(Li) detectors.

• Received 20 October 1977

DOI:https://doi.org/10.1103/PhysRevC.17.944