Analyzing power in neutron-deuteron elastic scattering at Elabn=3 MeV

A measurement of the analyzing power Ay(θ) in neutron-deuteron (n-d) elastic scattering below the deuteron breakup threshold is described, including a detailed discussion of the experimental apparatus and the treatment of systematic errors. The data provide a precise test of Faddeev calculations of the three-nucleon system and of the nucleon-nucleon interaction models used as inputs to these calculations. Ay was measured at six angles from 44.5 degree c.m. to 145.7 degree c.m. to a precision of (7--13)x10-4. Polarized neutrons, produced by the 3H(rvec p,rvec n)3He reaction, were incident upon the target, a deuterated organic scintillator. Scattered neutrons were detected in fast coincidence with the recoil deuterons in the target. A computer simulation of the experiment was used to compensate for a number of systematic errors. Particularly important were corrections for neutron multiple scattering, accidental coincidences, and finite geometry effects. The Ay data have a 2.2% scale factor uncertainty associated with uncertainty in the polarization of the incident neutron beam. The incident neutron polarization was measured in a separate experiment using n-4He scattering from a liquid helium scintillator. The neutron polarization measurement also yielded an improved value for the polarization transfer coefficient [Kyy(0degree)=0.650±0.019] in the 3H(rvec p,rvec n)3He reaction at Elabp=3.80 MeV. A comparison of the Ay data to Faddeev calculations shows that the discrepancy in Ay observed previously at higher energies continues below the breakup threshold. The Ay data are compared to a recent phase shift analysis of proton-deuteron scattering