Neutron-proton analyzing power at 12 MeV and inconsistencies in   parametrizations of nucleon-nucleon data
  We present the most accurate and complete data set for the analyzing power Ay(theta) in neutron-proton scattering. The experimental data were corrected for the effects of multiple scattering, both in the center detector and in the neutron detectors. The final data at En = 12.0 MeV deviate considerably from the predictions of nucleon-nucleon phase-shift analyses and potential models. The impact of the new data on the value of the charged pion-nucleon coupling constant is discussed in a model study. 
R.T. Braun, W. Tornow, C.R. Howell, D.E. Gonzalez Trotter, C.D. Roper,   F. Salinas, H.R. Setze, R.L. Walter, and G.J. Weisel