The Angular Correlation of the Cascade Gamma Rays from the Decay ofAu198

The angular correlation of the 0.411-Mev and 0.64-Mev cascade gamma rays resulting from the beta decay of ${\mathrm{Au}}^{198}$ to ${\mathrm{Hg}}^{198}$ has been measured with scintillation counters. If only pure multipole radiations are assumed, the experimental data do not agree with theoretical calculations for any reasonable values of the spins of the relevant states in ${\mathrm{Hg}}^{198}$. They do agree well, however, with spins of 0, 2, and 2 for the ground state, 0.411-Mev state, and 1.09-Mev state of ${\mathrm{Hg}}^{198}$, respectively, if the first transition (0.68-Mev gamma) is assumed to be a mixture of 60 percent dipole and 40 percent quadrupole radiation and the second transition (0.41-Mev gamma) is assumed to be pure quadrupole radiation. The parities of all three states are the same, presumably even. These results are in general agreement with the internal conversion measurements of other investigators.