The bombardment of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ by ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ ions has been used to study the properties of excited states in ${}_{}{}^{213}{}_{}{}^{}\mathrm{At}$, ${}_{}{}^{212}{}_{}{}^{}\mathrm{Po}$, and ${}_{}{}^{210}{}_{}{}^{}\mathrm{Pb}$. In-beam measurements with Ge(Li), intrinsic Ge, and Si surface barrier detectors of $\alpha$-decay excitation functions, $\alpha -\gamma$ coincidences, $\gamma -\gamma$ coincidences, $\gamma$-ray angular distributions, and pulsedbeam-$\gamma$ timing were made to establish decay schemes, level energies, $\gamma$-ray multipolarities, spin-parity assignments, and isomeric lifetimes. Excited states with spins up to $\frac{19}{2} \hslash$ in ${}_{}{}^{213}{}_{}{}^{}\mathrm{At}$ and $6 \hslash$ in ${}_{}{}^{212}{}_{}{}^{}\mathrm{Po}$ were identified. The mean lifetimes of the 1272-keV $8^{+}$ and 1193-keV $6^{+}$ states in ${}_{}{}^{210}{}_{}{}^{}\mathrm{Pb}$ were measured to be 225(22) and 30(10) nsec, respectively. These lifetimes imply $B\left(E2\mathrm{}\right)\mathrm{}$ values of $51\left(12\right)\mathrm{}{e}^2$ ${\mathrm{fm}}^4$ for the $8^{+}$ state and $308\left(115\right)\mathrm{}{e}^2$ ${\mathrm{fm}}^4$ for the $6^{+}$ state. The ${}_{}{}^{213}{}_{}{}^{}\mathrm{At}$ decay scheme and the ${}_{}{}^{210}{}_{}{}^{}\mathrm{Pb}$ $B\left(E2\mathrm{}\right)\mathrm{}$ values are compared with shell model calculations.

NUCLEAR REACTIONS ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,$2n$)${}_{}{}^{213}{}_{}{}^{}\mathrm{At}$, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,$t$)${}_{}{}^{212}{}_{}{}^{}\mathrm{Po}$, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$(${}_{}{}^7{}_{}{}^{}\mathrm{Li}$,$\alpha p$)${}_{}{}^{210}{}_{}{}^{}\mathrm{Pb}$, $E_{\mathrm{Li}}=30-34\mathrm{}$ MeV; measured $\alpha$-decay excitations, $\alpha -\gamma$ coincidences, $\gamma -\gamma$ coincidences, ${\gamma }_{-}W\left(\theta \right)$, pulsed-beam-$\gamma$ timing; deduced level schemes, $\gamma$ multipolarities, $J^{\pi }$, $T_{\frac{1}{2}}$, $B\left(E2\mathrm{}\right)\mathrm{}$.

• Received 9 July 1979

DOI:https://doi.org/10.1103/PhysRevC.21.1838