Measurement of the parity violating asymmetry AγAγ in +p→d+γn⃗+p→d+γ

Abstract

The weak pion-nucleon coupling constant Hπ1Hπ1 remains poorly determined, despite many years of effort. The recent measurement of the 133Cs133Cs anapole moment has been interpreted to give a value of Hπ1Hπ1 almost an order of magnitude larger than the limit established in the 18F18F parity doublet experiments. A measurement of the gamma ray directional asymmetry AγAγ for the capture of polarized neutrons by hydrogen has been proposed at Los Alamos National Laboratory. This experiment will determine Hπ1Hπ1 independent of nuclear structure effects. However, since the predicted asymmetry is small, Aγ ≈ 5×10−8,Aγ≈5×10−8, systematic effects must be reduced to <5×10−9.<5×10−9. The design of the experiment will is presented, with an emphasis on the techniques used for controlling systematic errors. © 1999 American Institute of Physics.