The directional angular correlations of the 208.36-112.97 kev gamma-gamma cascade in ${\mathrm{Hf}}^{177}$ and the 89.36-343.40 and 282.57-113.81 kev cascades in ${\mathrm{Lu}}^{175}$ have been measured with a coincidence scintillation spectrometer using NaI detectors. The observed correlation functions obtained with dilute aqueous solution sources are $W\left(\theta \right)=1-(0.1614\mathrm{}\pm 0.0015)P_2\left(cos\theta \right)$, $W\left(\theta \right)=1+(0.001\mathrm{}\pm 0.004)P_2\left(cos\theta \right)$, and $W\left(\theta \right)=1+(0.221\mathrm{}\pm 0.004)P_2\left(cos\theta \right)$, respectively.

These results, taken together with conversion coefficient measurements, indicate that ${\delta }^2$ for the 282.57-kev gamma ray in ${\mathrm{Lu}}^{175}$ is 0.05. The sign of $\delta$, defined below, is positive. The mixing ratio of the 208.36-kev gamma ray in ${\mathrm{Hf}}^{177}$ is $\frac{M2\mathrm{}}{E1\mathrm{}}=0.001\mathrm{}$; in this case the sign of $\delta$ is negative. The sign of $\delta$ for the 113.81-kev gamma ray in ${\mathrm{Lu}}^{175}$ is positive, and the sign of $\delta$ for the 112.97-kev gamma ray in ${\mathrm{Hf}}^{177}$ is negative.

• Received 4 November 1957

DOI:https://doi.org/10.1103/PhysRev.109.1652