Test of Charge Symmetry in Neutron-Proton Elastic Scattering at 477 MeV

Abstract

An experiment resulting in the first measurement of the isospin-mixing, charge-symmetry-violating component of the $n\ensuremath{-}p$ interaction has been performed. The experiment determined the difference in the angles of the zero crossing of the neutron and proton analyzing powers ${A}_{n}$ and ${A}_{p}$ at 477 MeV. In terms of the laboratory scattering angle of the neutron, the measured difference is ${\ensuremath{\theta}}_{0n}({A}_{n})\ensuremath{-}{\ensuremath{\theta}}_{0n}({A}_{p})=+0.13\ifmmode^\circ\else\textdegree\fi{} \ifmmode\pm\else\textpm\fi{}0.06\ifmmode^\circ\else\textdegree\fi{} (\ifmmode\pm\else\textpm\fi{}0.03\ifmmode^\circ\else\textdegree\fi{})$, where the second error is a worst-case estimate of systematic error. The resulting difference in the analyzing powers at the zero-crossing angle is ${A}_{n}\ensuremath{-}{A}_{p}=+0.0037 \ifmmode\pm\else\textpm\fi{}0.0017 (\ifmmode\pm\else\textpm\fi{}0.0008)$.