Momentum Conservation in the Beta-Decay ofP32and the Angular Correlation of Neutrinos with Electrons

Abstract

It is possible, by evaporation of carrier free ${\mathrm{P}}^{32}$, to produce what appear to be monolayer beta-active sources. These sources maintain their characteristics for several hours in a good vacuum. The momentum of the recoil ion is measured by timing its flight in a field-free space. Recoil momentum spectra are observed at 180°, 135°, 90°, and 45° with respect to the electrons. It is shown that (a) momentum is not conserved between the electron and the recoil nucleus, (b) the experimental data are in disagreement with any hypothesis in which the neutrino and the electron are most probably emitted in the same hemisphere, (c) for recoil ions above about 25 ev energy, the observed recoil momentum spectra agree rather well with those spectra calculated on the assumption of a ($1-\beta cos\theta$) neutrino-electron angular correlation function, and (d) below 25 ev too many recoils are observed compared to any neutrino theory which gives agreement for high momentum recoils. Since the reason for the disagreement below 25 ev is not understood, the selection of the ($1-\beta cos\theta$) function must be regarded as tentative.