Measurements of Spatial Asymmetries in the Decay of Polarized Neutrons

A series of experiments has been carried out to examine the spatial symmetry properties of the beta decay of the free neutron. Measurements of angular distributions of the electrons and protons coming from the decay of polarized neutrons have shown that the correlation coefficient between the directions of electron momentum and neutron spin is -0.11±0.02 and that between the antineutrino momentum and the neutron spin is 0.88±0.15. The coefficient of the term proportional to the scalar triple product of antineutrino momentum, electron momentum, and neutron spin (which is not invariant under time reversal) is 0.04±0.05. All these results are consistent with the $A-V$ theory of beta decay. Details of measurement techniques and the method of producing a beam of polarized neutrons are given.