Verification of Muon-Electron Universality in Charm Decay

Abstract

In a tungsten beam-dump experiment performed at Fermilab, 1480 neutrino-induced muonless events were observed. The prompt ${\nu }_e$ flux was determined both by subtraction of residual ${\nu }_{\mu }$ and nonprompt ${\nu }_e$ interactions and by use of the difference between the longitudinal energy deposition of electromagnetic and hadronic showers. The ratio of the prompt ${\nu }_e$ flux to the ${\nu }_{\mu }$ flux was measured to be 0.95 ±0.12 ±0.08 for $E_{\nu }>20\mathrm{}$ GeV and was consistent with unity throughout the range of energy and transverse momentum accessible to the experiment.