I. Danilchenko

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.

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.

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

Dilepton and strange particles production by neutrinos in gargamelle

Abstract New results are presented of an analysis of pictures taken during an exposure of Gargamelle to the CERN ν beam in 1975. In addition to three ν μ +N→ μ − +e + +V 0 + hadrons events previously reported, an excess is found of events of the type ν μ +N→ μ − +e + + hadrons without V 0 . An analysis of strange particle production in charged current events suggests a possible violation of the ΔS = ΔQ rule. Interpreted in terms of charm production, the data permit an estimate of branching ratios and production rate of charmed particles. A limit is also placed on charmed particle production by neutral currents.

Upper limit to the cross-section for the process νμ + e- → νμ + e-

Abstract An upper limit of 3 × 10−42 Eν cm2 per electron, at 90% confidence level, has been obtained for the cross section of the process νμ + e− → νμ + e−, interpreted in the usual V-A framework, for an electron recoil energy larger than 0.3 GeV. This estimate is based on the observation of one candidate event in exposures of Gargamelle to the CERN PS neutrino beam.

Upper Limit to the Cross-Section for the Process Neutrino mu/ e- --> Neutrino mu/ e-

Abstract An upper limit of 3 × 10−42 Eν cm2 per electron, at 90% confidence level, has been obtained for the cross section of the process νμ + e− → νμ + e−, interpreted in the usual V-A framework, for an electron recoil energy larger than 0.3 GeV. This estimate is based on the observation of one candidate event in exposures of Gargamelle to the CERN PS neutrino beam.

Upper limit to the cross-section for the process nu /sub mu /+e/sup -/ to nu /sub mu /+e/sup -/

Abstract An upper limit of 3 × 10−42 Eν cm2 per electron, at 90% confidence level, has been obtained for the cross section of the process νμ + e− → νμ + e−, interpreted in the usual V-A framework, for an electron recoil energy larger than 0.3 GeV. This estimate is based on the observation of one candidate event in exposures of Gargamelle to the CERN PS neutrino beam.