New test of nucleon-nucleon potential models

We present new measurements of the analyzing power for np scattering at 10.03 MeV accurate to +- 1 x 10/sup -3/. A new source of systematic error, related to resonances in n-/sup 12/C scattering in the neutron detectors, is discussed. The interaction of the neutron magnetic moment with the Coulomb field of the proton is found to make a significant contribution to the analyzing power at the present level of accuracy. The results are compared to predictions of nucleon-nucleon potential models. New, improved values are reported for the p- and d-wave spin-orbit phase-shift splittings.