Precision measurement of the neutron β-decay asymmetry

Abstract

A new measurement of the neutron β-decay asymmetry A0 has been carried out by the UCNA Collaboration using polarized ultracold neutrons (UCNs) from the solid deuterium UCN source at the Los Alamos Neutron Science Center. Improvements in the experiment have led to reductions in both statistical and systematic uncertainties leading to A0=-0.11954( 55)stat(98)syst, corresponding to the ratio of axial-vector to vector coupling λ≡gA/g V=-1.2756(30). © 2013 American Physical Society.