Electron-Neutrino Angular Correlation in the Beta Decay ofNeon19

The electron-neutrino angular correlation in the beta decay of ${\mathrm{Ne}}^{19}$ has been measured by observing the energy spectrum of ${\mathrm{F}}^{19}$ recoil ions. The constant $\lambda$ in the angular correlation function [$1+\lambda \left(\frac{v_e}{c}\right){cos\theta }_{e\nu }$] was found to be $\lambda =-0.21\mathrm{}\pm 0.08$, indicating that the beta-decay interaction is of the form $\mathrm{STP}$ and not $\mathrm{VTP}$. The observed angular correlation leads to the result $\frac{{C_S}^2{\left|\int 1\right|}^2}{{C_T}^2{\left|\int \sigma \right|}^2}=0.69\mathrm{}\pm 0.17,$ which is consistent with ${C_S}^2\simeq {C_T}^2$ if the nuclear configuration is ${{\left(d_{\frac{5}{2}}\right)}^3}_{\frac{1}{2}}$, but not if the configuration is ${{\left(s_{\frac{1}{2}}\right)}^3}_{\frac{1}{2}}$. Most of the ${\mathrm{F}}^{19}$ recoils carried one unit of negative charge, but singly charged positive ions were also detected. The coincidence rate due to positive ions was about 10 percent of that due to negative ions. No doubly charged recoils were observed.