The $\beta -\gamma$ angular correlation in the decay of ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ has been measured using a symmetric four detector system and an activated LiF target. ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ was produced by the ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}(d, p){}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ reaction using a low-energy deuteron beam ($E_d=2\mathrm{}$ MeV). Correlation data were acquired for ${\theta }_{\beta -\gamma }=90\mathrm{}°$ and ${\theta }_{\beta -\gamma }=180\mathrm{}°$ and these data were analyzed for systematic differences as a function of electron energy ($E_{\beta }$). We report a corrected first order slope to the ratio of $\beta$ spectra $\frac{N\left(180\mathrm{}°\right)}{N\left(90\mathrm{}°\right)}$ of (+0.5 ±0.7)${10}^{-3\mathrm{}}$ ${\mathrm{}\left(\mathrm{MeV}\right)\mathrm{}}^{-1\mathrm{}}$, with an intercept for this ratio of 1.001 ±0.002. Incorporating this value for the slope with other data on the $A=20\mathrm{}$ system, we find an upper limit for the second class current contribution to the correlation which is less than $\frac{1}{3}$ of the contribution of weak magnetism and consistent with zero.

RADIOACTIVITY ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$; measured $\beta -\gamma$ angular correlation. Determined induced weak currents.

• Received 15 May 1978

DOI:https://doi.org/10.1103/PhysRevC.18.2704