Antineutrino scattering on free protons (or neutrino scattering off free neutrons) gives a unique measurement of neutron and proton structure and is a building block for predicting neutrino scattering on more complex nuclei.
Previous measurements have had to rely on scattering neutrinos off deuterium and then correct for nuclear effects, or use low intensity anti-neutrino beams. In this talk MINERvA will present the first high statistics cross section measurement of the charged current elastic process νμp → μ+n using the plastic scintillator (CH). The carbon background is significantly reduced and constrained with minimal model dependency using the kinematics of the reconstructed neutrons. The result can be directly compared with lattice QCD computations, and to electron scattering off free protons