A measurement of the antineutrino asymmetry B in free neutron decay

We have measured the antineutrino asymmetry B in neutron beta decay, i.e., the correlation of the neutron spin and the antineutrino momentum, with a new method. Our result is B = 0.967 +/- 0.006(stat) +/- 0.010(syst) = 0.967 +/- 0.012. Statistical and systematic uncertainty can be considerably reduced in future experiments. (c) 2005 Elsevier B.V. All rights reserved.