Directional Correlations in the Decay ofPm148

The directional correlation between the 1930-keV $\beta$ group and the 551-keV $\gamma$ in the decay of 5-day ${}_{}{}^{148}{}_{}{}^{}\mathrm{Pm}$ has been measured. The anisotropy is found to be only a few percent over the $\beta$ energy range from 1050 to 1800 keV. Directional correlations for the following $\gamma -\gamma$ cascades in the decay of 41-day ${}_{}{}^{148}{}_{}{}^{}\mathrm{Pm}$ have been measured: 414-630 keV, $A_2=-0.07\mathrm{}\pm 0.03$; 414-551 keV, $A_2=-0.04\mathrm{}\pm 0.03$; 288-630 keV, $A_2=0.17\mathrm{}\pm 0.02$; 288-551 keV, $A_2=0.19\mathrm{}\pm 0.02$. A note on simple properties of directional correlations involving unobserved $\gamma$ rays which hold in special cases is appended.