A search for new neutrino types and new neutrino sources using BEBC detector

The BEBC data of the 1977 and 1979 Beam Dump Experiments are analysed. It is shown that there are new neutrino production mechanisms which must be the decays of particles with life times less than about 10-9 to 10-10 seconds. A comparison between the expected neutrino fluxes coming from ''conventional'' sources and the observed charged current event spectrum shows an excess of neutrinos. The prompt neutrino flux is most probably due to charmed particle decays. The hadronic D meson production is found to be a process occurring predominantly around Feynman x=0. The corresponding production cross section is of the order of 20 microbarns at √s=27.4 GeV. An extensive search for tau neutrino interactions is performed. This includes the development of a new kinematic method for their detection. However, the data seem to contain no tau neutrino events. The uniquely high ratio of electron events to neutral currents in this experiment confirms that the coupling of the electron neutrino to the tau lepton is small or zero. It also leads to tight limits for the mixing between electron neutrinos and tau neutrinos. (author)