Neutron-Proton and Neutron-Carbon Scattering Amplitudes

Abstract

Measurements of the $n\ensuremath{-}p$ and $n\ensuremath{-}\mathrm{C}$ coherent atomic scattering amplitudes are described. The results ${a}_{\mathrm{H}}=\ensuremath{-}3.740\ifmmode\pm\else\textpm\fi{}0.003$ fm and ${a}_{C}=6.648\ifmmode\pm\else\textpm\fi{}0.003$ fm were obtained by reflection measurements on seventeen various liquid mirrors with the neutron gravity refractometer, for which a more accurate method of evaluation is given. The mirrors were composed of the elements hydrogen, carbon, and chlorine. The atomic scattering amplitude of chlorine was found to be ${a}_{\mathrm{Cl}}=9.580\ifmmode\pm\else\textpm\fi{}0.002$ fm. The new ${a}_{\mathrm{H}}$ is of importance for describing the $n\ensuremath{-}p$ system.