Pb $K$ x rays and ∼ 1.08-MeV $K$-conversion electrons have been found among radiations emitted in the decay of 4.2-min ${}_{}{}^{206}{}_{}{}^{}\mathrm{Tl}$. These radiations imply the existence of weak $\beta$ transitions (0.08%) to the 1.17-MeV $0^{+}$ state in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$, which decays primarily by an $E0\mathrm{}$ transition to the ground state.

• Received 29 November 1971

DOI:https://doi.org/10.1103/PhysRevLett.28.107