H.P. Paar

Inclusive interactions of high-energy neutrinos and antineutrinos in iron

We present results on charged current inclusive neutrino and antineutrino scattering in the neutrino energy range 30–200 GeV. The results include a) total cross-sections; b)y distributions; c) structure functions; and d) scaling violations observed in the structure functions. The results, as well as their comparison with the results of electron and muon inclusive scattering, are in agreement with the expectations of the quark parton model and QCD.

A detector for high-energy neutrino interactions

Abstract We describe the design, construction and performance of a large mass detector used at CERN to study high-energy neutrino interactions in iron. This detector combines magnetic spectrometry and hadron calorimetry techniques.

Opposite sign dimuon events produced in narrow band neutrino and antineutrino beams

Abstract On the basis of 315 dimuon events of opposite sign for which the nature (and energy) of the incident neutrino is known, and the momenta and hadronic shower energy are measured, we find a) very similar production by neutrinos and antineutrinos, and therefore confirmation of the GIM model for semileptonic weak interactions, b) energy spectra, excitation functions, angular correlations and transverse momentum distributions which are in remarkable agreement with the hypothesis of charm production and decay, c) evidence against models for which the second muon has a heavy lepton as origin, d) evidence against “bottom” quark production by antineutrinos, e) the amount and the structure function for the strange quark-antiquark sea, and f) an approximate branching ratio, of 0.15 for the muonic decay of the semistable charmed meson.

QCD analysis of charged-current structure functions

Abstract The structure functions F 2 ( x , Q 2 ) and xF 3 ( x , Q 2 ) measured in high-energy neutrino charged-current interactions on nuclei are compared with QCD predictions. Solutions to the moment equations of QCD are found which are in good agreement with the data and yield simple parametrisations of the structure functions. For the scale parameter Λ we find Λ = 0.5 ± 0.2 GeV. The analysis also results in values for the width of the gluon distribution as a function of Q 2 . We find 〈 x 〉 gluons = 0.16 ± 0.03 for Q 2 = 10 GeV 2 .

Performance of a magnetized total absorption calorimeter between 15 GeV and 140 GeV

Abstract We have calibrated a magnetized iron-scintillator sandwhich calorimeter in a hadron beam, finding an energy resolution equal to 16% fwhm at 140 GeV with 5 cm sampling. The hadron energy resolution (fwhm/mean) improves as E − 1 2 between 15 and 140 GeV. No effect due to the magnetic field was observed. Longitudinal and lateral shower containment were also investigated.

Measurement of the neutral to charged current cross section ratio in neutrino and antineutrino interactions

Abstract We report on the analysis of inclusive neutral current events produced in neutrino and antineutrino narrow band beams. We find for incident neutrino energies in the range 12–200 GeV and for hadron energies above 12 GeV a neutral to charged current cross-section ratio of R v = 0.293 ± 0.010 for incident neutrinos, and R v = 0.35 ± 0.03 for antineutrinos. These ratios are consistent with the Weinberg-Salam model, with sin 2 θ w = 0.24 ± 0.02.

Study of inclusive neutral current interactions of neutrinos and antineutrinos

Abstract We report on results from a study of hadron-energy distributions for ν and ν inclusive neutral current interactions. There is no significant variation of the neutral to charged current total cross-section ratios R ν and R ν with neutrino energy. The space-time structure of neutral currents is dominated by V − A , with a significant admixture of V + A . The Weinberg-Salam model is in agreement with all data if sin 2 θ w =0.24±0.02.

Comparison of moments from the valence structure function with QCD predictions

Abstract We present moments (both ordinary and Nachtmann) of the nucleon valence structure function measured in high Q 2 ν FE scattering, supplemented by data from deep inelastic eD scattering. These data seem to agree with QCD predictions for vector gluons. The QCD parameter Λ is found to be of the order 0.5 GeV.

Observation of trimuon events produced in neutrino and antineutrino interactions

Abstract We report two trimuon events producedin v interactions. Of these, one is of the charge type −++, not previously reported. In an antineutrino exposure, one candidate of the charge type +−− has been observed. This type of event has also not been reported previously. The combined π → μ and K → μ background for the three events are calculated to be ∼ 0.7 events. The rate relative to charged current events corresponding to these three events is of the order of 4 × 10 −5 .

Search for single positive muon production in neutrino interactions

Abstract A search has been made for neutrino interactions with a positive (wrong-sign) muon in the final state. All the events found can be attributed to known sources. A cut at a visible energy of 100 GeV leaves one event, giving an upper limit for μ + production relative to μ - of 1.6 × 10 −4 at the 90% confidence level. Upper limits are given for (a) charm-changing neutral currents, (b) positive heavy-lepton production, and (c) neutrino-antineutrino oscillations.