Status of neutron-proton scattering in the energy range from 20 to 70 MeV

The present status of neutron-proton scattering in the energy range from 20-70 MeV is reviewed. The data base covers total cross sections, differential cross sections and polarization observables. The efforts after 1980 did largely concentrate on precision measurements of the differential cross sections and accurate vector analyzing powers, using polarized neutron beams. Because of correlations between various phase parameters in the phase-shift analyses of scattering observables, neutron-proton spin-spin correlation parameters have been measured at various laboratories. These measurements employed besides a polarized neutron beam in addition a polarized hydrogen target. For completeness, some representative neutron-proton capture data are included