Critical review of the present experimental status of neutron-proton scattering up to 1 GeV

The present experimental status of elastic neutron-proton scattering at energies up to 1 GeV is reviewed. Open questions that should be answered by a new generation of experiments are emphasized. These include detailed tests of fundamental symmetries, such as time reversal invariance and isotopic spin conservation. Experimental data are reviewed and shown to be insufficient over the whole energy range and sometimes inconsistent. Therefore phase shifts solutions will probably change significantly once new data are included. Of course, no direct amplitude reconstruction of np scattering is possible yet