Polarization in neutron-proton scattering at 29.6 MeV

The polarization in neutron-proton scattering at 29.6 MeV was deduced from asymmetries measured at every 10° c.m. from 50 to 150° c.m. The incident neutron beam was derived from a high-pressure deuterium gas cell via the ${}_{}{}^2{}_{}{}^{}\mathrm{H}(d, n){}_{}{}^3{}_{}{}^{}\mathrm{He}$ reaction at 37° c.m. The beam passed through a spin rotation magnet and, at the target location 5.4 m from the gas cell, possessed a flux of 5 × ${10}^5$ n/sec and a polarization of 0.32 ± 0.04. Data between 50 and 110° c.m. were obtained using scintillating CH target in coincidence with neutron detectors, while data between 120 and 150° c.m. were obtained using recoil protons from a C${\mathrm{H}}_2$ target. Total errors in the derived polarizations ranged from ± 0.007 to ± 0.022. These data agree very well with three previous values measured near 30 MeV at Los Alamos, but they disagree with Harwell data indicating small or negative polarizations near 150° c.m. The present results agree well with predictions of the Livermore X and Yale IV phase shift sets, but slightly favor the former.