Observation of Elastic Neutrino-Proton Scattering

Abstract

We have observed thirty events of the process $\ensuremath{\nu}p\ensuremath{\rightarrow}\ensuremath{\nu}p$ with a background expectation of seven events. The neutral-current to charged-current ratio $\frac{\ensuremath{\sigma}(\ensuremath{\nu}p\ensuremath{\rightarrow}\ensuremath{\nu}p)}{\ensuremath{\sigma}(\ensuremath{\nu}n\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}p)}$ is measured to be 0.17\ifmmode\pm\else\textpm\fi{}0.05 for $0.3<{q}^{2}<0.9$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$ where $\ensuremath{-}{q}^{2}$ is the square of the four-momentum transfer to the proton.