# Electron-Neutrino Angular Correlation in the Beta Decay of Neon-19

The electron-neutrino angular correlation in the beta decay of Ne" has been measured by observing the energy spectrum of Pie recoil ions. The constant k in the angular correlation function L1+l~(v, /c) eosg, was found to be X= — 0.21&0. 08, indicating that the beta-decay interaction is of the form S1'I' and not UTP. The observed angular correlation leads to the result [equation] which is consistent with Cs Crs ii the nuclear configuration is (ds/s)'us, but not if the configuration is (s»&)'&12. Most of the F" 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.

Recent measurements of the electron-neutrino angular correlation in the beta decay of He6 have indicated that the beta-decay interaction includes a tensor component and that the axial vector component is small or zero. The interaction must also include a scalar or (polar) vector component, as has been recog+ nized since the discovery' ' of allowed J=O — 0 transitions in the decay of C10, 014, and Cl34. The principal objective of this experiment was to identify the Fermi (S or V) part of the interaction by measuring the angular correlation in an allowed transition of the type ΔJ=0, with no change of parity.

,According to Eq. (3), the experimental result X = —0.21 indicates that the beta-decay interaction contains a scalar component and that the (polar) vector component is small or zero. The interaction is therefore of the form STP. This conclusion is based on the results of the He6 experiments of Allen and Jentschke and of Rustad and Ruby, ' (2) the results of this experiment, and (3) the assumption of negligible Fierz interference. The result that the interaction STP is in agreement with the conclusions of Mahmoud and Konopinski and of Peaslee, who have analyzed the shapes of beta spectra observed in allowed and forbidden transitions, and is also consistent with the observations of Alford and Hamilton" in their recoil experiment on Ne19.