The $T$ 23 states in ${}_{84}{}^{210}{}_{}{}^{}\mathrm{Po}_{126}^{}{}_{}{}^{}(T_3=21)$ which are the isobaric analogs of the $T=T_3=23\mathrm{}$ ground state and low-lying states in ${}_{82}{}^{210}{}_{}{}^{}\mathrm{Pb}_{128}^{}{}_{}{}^{}$ have been observed as enhancements in the excitation function for the reaction $p+{}_{83}{}^{209}{}_{}{}^{}\mathrm{Bi}_{126}^{}{}_{}{}^{}\to {}_{82}{}^{208}{}_{}{}^{}\mathrm{Pb}_{126}^{}{}_{}{}^{}+2p$. The experimentally observed enhancements in the two-proton coincidence excitation function correlate with the known level structure of ${}_{}{}^{210}{}_{}{}^{}\mathrm{Pb}$ and occur at the incident proton energies predicted by Coulomb energy formulas, thus establishing that these enhancements are due to the population of double analog levels in ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$.

• Received 26 August 1971

DOI:https://doi.org/10.1103/PhysRevLett.28.41