gVand gAand test the validity of the Electroweak Standard Model. Measurements
of a have an advantage over those of A in that they do not require a polarized.
The aCORN experiment: a measurement of the electron-antineutrino correlation a in neutron beta decay M. Scott Dewey National Institute of Standards and Technology, USA
Compared with the neutron lifetime τn and the electron-neutron spin correlation coefficient A, the electron-antineutrino correlation coefficient a is poorly known (4%). It too can be used to determine the weak and axial vector coupling constants gV and gA and test the validity of the Electroweak Standard Model. Measurements of a have an advantage over those of A in that they do not require a polarized neutron beam. A new experiment is being carried out at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) to measure this quantity. Whereas previous efforts relied upon precise proton spectroscopy to extract the value of a, the current experiment has at its heart an asymmetry measurement. This changes in an essential way the systematic effects encountered in the measurement. We briefly review the fundamental neutron physics program at the NCNR and describe this new experiment.
