Results of a beam dump experiment at the CERN SPS neutrino facility

Abstract We report results from a beam dump experiment that has been performed at the CERN SPS neutrino facility using the CDHS neutrino counter detector. Limits on dimuon and trimuon production by new penetrating neutral particles are given. A new source of prompt electron and muon neutrinos has been observed giving (1.2±0.4)× 10 −7 ν e or ν μ per incident proton with neutrino angle smaller than 1.85 mrad and E ν > 20 GeV. If these prompt neutrinos are attributed to charmed meson pair production, the inclusive D D production cross section could be of the order of 30 ωb. If axions are existing their production rate relative to π 0 mesons is found to be less than 0.5 × 10 −8 .