Tensor Type (∫Bij) Component in the 2.31-MevβTransition ofSb124

Abstract

The $\beta -\gamma$ directional correlation of the first-forbidden 2.31-Mev $\beta$ transition of ${\mathrm{Sb}}^{124}$ and of the 0.603-Mev $\gamma$ ray of ${\mathrm{Te}}^{124}$ was measured. The integral $\beta -\gamma$ directional correlation measured at an average $\beta$ energy, $\overline{W}=4.8\mathrm{}$, is represented by $W_{\beta \gamma }(\theta , \overline{W}=4.8)=1-(0.390\mathrm{}\pm 0.011)P_2\left(cos\theta \right)+(0.004\mathrm{}\pm 0.013)P_4\left(cos\theta \right)$. The negligibly small $P_4\left(cos\theta \right)$ term provides additional evidence against a second-forbidden $\beta$ transition. The energy dependence of the anisotropy coefficient $A_2\mathrm{}\left(W\right)\mathrm{}$ in the correlation function $W_{\beta \gamma }(\theta , W)=1+A_2\mathrm{}\left(W\right)\mathrm{}\times P_2\left(cos\theta \right)$ was measured. The experimental values of $A_2\mathrm{}\left(W\right)\mathrm{}$ exclude the possibility of a pure $\int B_{\mathrm{ij}}$ transition, but give conclusive evidence that the $\int B_{\mathrm{ij}}$ matrix element contributes very significantly to the 2.31-Mev $\beta$ transition of ${\mathrm{Sb}}^{124}$. In fact, the directional correlation data are well represented, if $C_A\int B_{\mathrm{ij}}\cong -C_V\int i\alpha +\xi C_V\int \mathrm{r}-\xi C_A\int i\sigma \times \mathrm{r}$, where $\xi =\frac{Z\alpha }{2R}$.