Neutrino Experiment to Test the Nature of Muon-Number Conservation

Abstract

This paper reports on a search for ${\overline{\ensuremath{\nu}}}_{e}$ from ${\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}{\overline{\ensuremath{\nu}}}_{e}{\ensuremath{\nu}}_{\ensuremath{\mu}}$, allowed by multiplicative but not additive muon conservation, and for ${\ensuremath{\nu}}_{e}$ from ${\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}{\ensuremath{\nu}}_{e}{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$, allowed by both. Neutrinos from the Clinton P. Anderson Meson Physics Facility have been used, together with a six-ton Cherenkov counter filled with ${\mathrm{H}}_{2}$O (${\mathrm{D}}_{2}$O) to look for ${\ensuremath{\nu}}_{e}p\ensuremath{\rightarrow}n{e}^{+}({\ensuremath{\nu}}_{e}d\ensuremath{\rightarrow}\mathrm{pp}{e}^{\ensuremath{-}})$. The branching ratio $\frac{({\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}{\ensuremath{\nu}}_{e}{\ensuremath{\nu}}_{\ensuremath{\mu}})}{({\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}\mathrm{all})}=\ensuremath{-}0.001\ifmmode\pm\else\textpm\fi{}0.040$ is in excellent agreement with the additive law. The cross section $〈\ensuremath{\sigma}({\ensuremath{\nu}}_{e}d\ensuremath{\rightarrow}\mathrm{pp}{e}^{\ensuremath{-}})〉=(0.52\ifmmode\pm\else\textpm\fi{}0.18)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}40}$ ${\mathrm{cm}}^{2}$ agrees with theory.