THE ELECTRON-NEUTRINO ANGULAR CORRELATION IN BETA DECAY OF HELIUM 6
The electron-neutrino angular correlation in decay of He 6 has been determined by measuring the distribution of electron energies and recoil velocities without selection of angle. The correlation parameter α was found to be -0.353 -0.053+0.033, confirming current belief that the Gamow-Teller interaction is of axial vector type. The maximum admixture of a tensor interaction is given by |C T| 2/|C A| 2 < 0.08.
On the debit side, apart from smaller counting rates, coincidence experiments are generally more critically sensitive to the distribution of activity within and near the source volume on account of changing solid angle efficiencies. Uncertainty in the source distribution has in the past led to serious errors in both r-recoil angular correlations 18, ~) and in recoil T.O.F. distributions zl, a).