Prompt neutrino results from a proton beam dump experiment

A study of prompt neutrino events from 400 GeV protons on a beam-dump is presented. The ratio of electron- to muon-neutrino rates is 0.86±0.14, in agreement withe−μ universality. The anti-neutrino to neutrino flux ratio is $$\bar v_\mu /v_\mu = 0.81 \pm 0.19$$ . The absolute rates and distributions observed are shown to be in quantitative agreement with the known properties of charmedquark production in hadron collisions.