Alexander K. Komives (a)(b), Fred B. Bateman (b), Maynard S. Dewey (a)(b), Thomas R. Gentile (a), Jeff S. Nico (a), Alan K. Thompson (a)(b)

National Institute of Standards and Technology

W. M. Snow (a) Indiana University B.G. Yerozolimsky (b), L. Goldin (b)

Harvard University

YU.A. Mostovoy (b), S. Balashov (b)

Kurchatov Institute

R. Anderman (b), G.L. Jones (b)

Hamilton College

(a) A+B measurement , (b) "a" measurement

Neutron decay, one of the simplest examples of beta decay, is an ideal
system for studying the weak interaction. The distribution of neutron decays
depends on four distinct combinations of neutron spin polarization and
decay product momenta. Determining the strength of this dependency on each
combination yields four correlation coefficients. Improving the precision
of these measurements provides increasingly stringent tests of the Electroweak
Standard Model, which describes interactions between fundamental particles.
Several of these coefficients are being determined at the NIST Center for
Neutron Research. The development and progress being achieved on two of
these experiments are described in this presentation. The first measurement
determines the sum of two neutron decay coefficients, A and B. This sum
is directly proportional to the asymmetry in the number of protons emitted
parallel or anti-parallel to the neutron spin. A measurement of this asymmetry,
which has never been successfully performed, would provide an independent
method of determining the ratio of the axial vector to vector weak coupling
coefficients. This ratio can be used to determine the need for extensions
to the Electroweak Standard Model. Several tests and their implications
on the performance of the experiment are presented. The second eperiment
determines "a" - the electron-antineutrino angular correlation coefficient.
A novel technique, which will circumvent some of the problems associated
with earlier measurements of "a", will be utilized. An electron spectrometer
that strongly suppresses backscattered electrons will be required. It is
the development and testing of the prototype spectrometer and its implications
for the "a" measurement that is the focus of this presentation.