J. Morfin

Observation of Neutrino Like Interactions Without Muon Or Electron in the Gargamelle Neutrino Experiment

Abstract Events induced by neutral particles and producing hadrons, but no muon or electron, have been observed in the CERN neutrino experiment. These events behave as expected if they arise from neutral current induced processes. The rates relative to the corresponding charged current processes are evaluated.

Search for elastic muon-neutrino electron scattering

Abstract One possible event of the process ν − μ + e − → v − μ + e − has been observed. The various background processes are discussed and the event interpreted in terms of the Weinberg theory. The 90% confidence limits on the Weinberg parameter are 0.1 2 θ W

Measurement of the neutrino--nucleon and antineutrino--nucleon total cross sections

Abstract The v and v nucleon total cross-sections have been determined as a function of energy using a sample of 2500 v and 950 v event. The results are compared with predictions of scaling and charge symmetry hypotheses.

Observation of neutrino-like interactions without muon or electron in the Gargamelle neutrino experiment

Events induced by neutral particles and producing only hadrons, but no muon or electron, have been observed in the heavy liquid bubble chamber Gargamelle exposed to neutrino (v) and antineutrino (v) beams at CERN. A study of the various sources which could give rise to such events reveals that less than 20% could be attributed to neutrons or KL°. The events behave as expected if they arise from neutral current processes induced by neutrinos and antineutrinos. The ratio of the number of these events to the number of corresponding events with charged lepton is 0.22 ± 0.04 for v and 0.43 ± 0.12 for v.

Observation of an excess of νe, νe events in a beam dump experiment at 400 GeV

Abstract A beam dump experiment has been performed at CERN in Gargamelle using the neutrino facility to look for penetrating particles produced either directly in the beam interaction or by prompt decay of new particles. A total of 32 interactions with a visible energy greater than 10 GeV has been found, classified, aftercorrections, into 18 charged current ν μ or ν μ , 5.1 neutral current and 8.9 ν e or ν e charged current events. An excess of ν e events remains after all subtractions from any established sources. Results are presented in terms of the product of the cross section and the leptonic decay branching ratio of the possible source.

Observation of an Excess of electron-neutrino, anti-electron-neutrino Events in a Beam Dump Experiment at 400-GeV

Abstract A beam dump experiment has been performed at CERN in Gargamelle using the neutrino facility to look for penetrating particles produced either directly in the beam interaction or by prompt decay of new particles. A total of 32 interactions with a visible energy greater than 10 GeV has been found, classified, aftercorrections, into 18 charged current ν μ or ν μ , 5.1 neutral current and 8.9 ν e or ν e charged current events. An excess of ν e events remains after all subtractions from any established sources. Results are presented in terms of the product of the cross section and the leptonic decay branching ratio of the possible source.

Evidence for the leptonic neutral current reaction νμ+e-→νμ+e-

Abstract In the Gargamelle neutrino experiment, three unambiguous candidates for the reaction ν μ + e − → ν μ e − have been observed corresponding to a cross section for a recoil electron energy within the range 0.3 e − GeV of 0.06 × 10 −41 E ν ( GeV ) cm 2 / electron . The calculated background is 0.44 ± 0.13 events and the probability that all three candidates could be due to this background is 1%.

Evidence for the Leptonic Neutral Current Reaction anti-Muon-neutrino e- ---> anti-Muon-neutrino e-

Abstract In the Gargamelle neutrino experiment, three unambiguous candidates for the reaction ν μ + e − → ν μ e − have been observed corresponding to a cross section for a recoil electron energy within the range 0.3 e − GeV of 0.06 × 10 −41 E ν ( GeV ) cm 2 / electron . The calculated background is 0.44 ± 0.13 events and the probability that all three candidates could be due to this background is 1%.

Observation of muon-neutrino reactions producing a positron and a strange particle

Abstract In addition to one previously reported event, a second event, in which a positron is observed together with a strange particle and a negative muon, has been seen in the bubble chamber Gargamelle exposed to the CERN neutrino beam. The level of the background for this type of event is found to be very low. The data strongly indicate the existence of a new type of interaction leading to a charged lepton pair correlated with a strange particle in the final state. The interpretation of these two events in terms of production of a charmed hadron is presented.

Experimental Study of Exclusive One Pion Production in All Neutrino Induced Neutral Current Channels

Abstract Results are presented on exclusive single-pion production in the bubble chamber Gargamelle, filled with a light propane-freon mixture, and exposed to the focused neutrino wide-band beam at the CERN PS. The results are corrected for nuclear reinteractions. The isospin structure of the weak neutral current is analysed using all four single-pion channels. The isovector-isoscalar interference term is measured and found to differ from zero by two standard deviations. Evidence of Δ production by the weak neutral