The degree of circular polarization of gamma rays following allowed beta transitions has been investigated as a function of the angle ${\Theta }_{\beta \gamma }$ between beta-particle momentum and gamma direction and as a function of the energy of the beta particle. The anisotropy of the beta-gamma circular polarization correlation observed for pure Gamow-Teller transitions ($\Delta I=1\mathrm{}$) is used to determine the validity of ${C_A}^{\prime }=C_A$. The experimental results for ${\mathrm{Co}}^{60}$ and ${\mathrm{Na}}^{22}$ are $W\left({\Theta }_{\beta \gamma }\right)=1-(0.345\mathrm{}\pm 0.019)\left(\frac{v}{c}\right){cos\Theta }_{\beta \gamma }$ and $W\left({\Theta }_{\beta \gamma }\right)=1+(0.35\mathrm{}\pm 0.02)\left(\frac{v}{c}\right){cos\Theta }_{\beta \gamma }$, respectively. These values yield ${C_A}^{\prime }=(1\mathrm{}\pm 0.2)C_A$.

The degree of circular polarization of the gamma rays following mixed beta transitions ($\Delta I=0\mathrm{}$) confirms the existence of $V-A$ interference terms. For ${\mathrm{Sc}}^{46}$ and ${\mathrm{Na}}^{24}$ the beta-gamma circular polarization correlations, $W\left({\Theta }_{\beta \gamma }\right)=1+(0.24\mathrm{}\pm 0.02)\left(\frac{v}{c}\right){cos\Theta }_{\beta \gamma }$, and $W\left({\Theta }_{\beta \gamma }\right)=1+(0.07\mathrm{}\pm 0.03)\left(\frac{v}{c}\right){cos\Theta }_{\beta \gamma }$, were observed. From these measurements the ratios of Fermi to Gamow-Teller components for the ${\mathrm{Sc}}^{46}$ beta transition, ${\left(\frac{M_{\mathrm{F}}}{M_{\mathrm{GT}}}\right)}^2=0.13\mathrm{}\pm 0.04$, and for the ${\mathrm{Na}}^{24}$ beta transition, ${\left(\frac{M_{\mathrm{F}}}{M_{\mathrm{GT}}}\right)}^2=0.002\mathrm{}\pm 0.010$, were determined.

• Received 23 March 1959

DOI:https://doi.org/10.1103/PhysRev.115.980