Discrepancies between Global Nucleon-Nucleon Phase Shifts and New Data forn−pScattering at 16.9 MeV

Data for the analyzing power $A_y\left(\theta \right)$ for $n-p$ scattering at 16.9 MeV have been measured for the range from 50 to 145° (c.m.). Eleven values are reported to an accuracy of about ±0.002, the highest overall precision ever obtained in any fast-neutron polarization experiment. Predictions based on phase-shift sets obtained from global analyses of nucleon-nucleon scattering disagree significantly with the new data. The data are sufficiently precise to show a dependence on the $f$-wave spin-orbit phase parameter.