Time-Dependent Directional Correlation of 1.1-hrPb204

A study is made of an effect attributable to the interaction of the electric quadrupole moment of the 0.27 μsec level of ${\mathrm{Pb}}^{204}$ with the crystalline electric field in metallic, polycrystalline, thallium in which 68-min ${\mathrm{Pb}}^{204}$ is produced by ($p, 2n$) reaction. The directional anisotropy in the rate of delayed coincidences between the $\gamma$ ray preceding the 0.27 μsec state and the $\gamma$ rays following the state is observed as a function of the delay time. Although some discrepancy between the observed function and theory is found, the time dependence suggests a coupling frequency $\frac{eQ\left(\frac{{\partial }^{2}V}{\partial z^2}\right)}{h}$ of 12 Mc/sec. Measurements of the directional correlation between the two gamma rays in prompt coincidence following the 0.27 μsec state supports the assignment, by Krohn and Raboy, of spin 4 to that state and of some mixing of $M3\mathrm{}$ with the dominantly $E2\mathrm{}$, 371-kev gamma ray. Evidence of prompt $\gamma$ rays of several energies, following $K$-capture in 12-hr ${\mathrm{Bi}}^{204}$, is also found.