Neutron-proton scattering. II. Spin correlation parameterAyy(θ)at 50 MeV

Abstract

We report on our remeasurement of the $n-p$ scattering observable $A_{\mathrm{yy}}\left(\theta \right)$, in which 50 MeV (lab) polarized neutrons were scattered from a polarized proton target. Several improvements to the target system have enabled us to greatly reduce the normalization uncertainty in $A_{\mathrm{yy}}$, compared to our earlier measurement. Incorporating these results in a phase shift analysis yields the results $\overline{\delta }\left({}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}\right)=-6.4\mathrm{}°\pm 1.1°$ and $\overline{\epsilon }=3.6\mathrm{}°\pm 1.0°$, where ${\overline{\epsilon }}_1$ is the ${}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}-{}_{}{}^3{}_{}{}^{}D_1^{}{}_{}{}^{}$ mixing parameter.