The decay of ${}_{}{}^{198}{}_{}{}^{}\mathrm{Bi}$ and ${}_{}{}^{200}{}_{}{}^{}\mathrm{Bi}$ to levels in the corresponding Pb daughters have been investigated using sources which were both mass-separated and chemically processed. $\gamma$-ray and conversion-electron singles spectra were obtained, as well as $\gamma -\gamma$ prompt- and delayed-co-incidence spectra. These data yield levels in ${}_{}{}^{198}{}_{}{}^{}\mathrm{Pb}$ at the following energies (spin-parities): 1062.9 ($2^{+}$), 1624.9 ($4^{+}$), 1822.3 [${\mathrm{}\left(5\right)\mathrm{}}^{-}$], and 2139.8 [${\mathrm{}\left(7\right)\mathrm{}}^{-}$] keV. Those in ${}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$ are at 1026.3 ($2^{+}$), 1488.3 ($4^{+}$), 1907.9 [${\mathrm{}\left(5\right)\mathrm{}}^{-}$], and 2152.9 [${\mathrm{}\left(7\right)\mathrm{}}^{-}$) keV. The half-life of the 1822-keV level in ${}_{}{}^{198}{}_{}{}^{}\mathrm{Pb}$ was determined to be 63.3 ± 2.5 nsec, and those of the 1908- and 2153-keV levels in ${}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$ are 1.50 ± 0.08 and 47.6± 2.5 nsec, respectively.

• Received 13 January 1972

DOI:https://doi.org/10.1103/PhysRevC.5.1751