Prompt Muon-Neutrino Production in a 400-GeV Proton Beam-Dump Experiment

Abstract

The prompt ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ flux produced by 400-GeV protons has been measured with a detector located 56 m from a tungsten target. The cross section for the hadronic production of charm is determined to be 27\ifmmode\pm\else\textpm\fi{}4\ifmmode\pm\else\textpm\fi{}5 \ensuremath{\mu}b/nucleon subject to the following assumptions: $D\overline{D}$ production only; ${A}^{1}$ variation of cross section; and a parametrization of the $D$-production cross section which is ${(1\ensuremath{-}x)}^{4}\mathrm{exp}(\ensuremath{-}2{m}_{\ensuremath{\perp}})$. The ratio of prompt ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ flux to prompt ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ is measured to be 1.12\ifmmode\pm\else\textpm\fi{}0.24\ifmmode\pm\else\textpm\fi{}0.17, consistent with predominantly $D\overline{D}$ production.