A study of quasi-elastic muon neutrino and antineutrino scattering in the NOMAD experiment

We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions using a set of experimental data collected by the NOMAD Collaboration. We have performed measurements of the cross-section of these processes on a nuclear target (mainly carbon).The axial mass parameter M was extracted from the measured quasi-elastic neutrino cross section. The corresponding result is M =1.05±0.02(stat)±0.06(syst) GeV. Our measured M is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of M is lower than those recently published by K2K and MiniBooNE Collaborations. However, within the large errors quoted by these experiments on M, these results are compatible with the more precise NOMAD value

Prediction of neutrino fluxes in the NOMAD experiment

The method developed for the calculation of the flux and composition of the West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations is described. The calculation is based on particle production rates computed using a recent version of FLUKA and modified to take into account the cross-sections measured by the SPY and NA20 experiments. These particles are propagated through the beam line taking into account the material and magnetic fields they traverse. The neutrinos produced through their decays are tracked to the NOMAD detector. The fluxes of the four neutrino flavours at NOMAD are predicted with an uncertainty of about 8% for nm and ne; 10% for %nm; and 12% for %ne: The energy-dependent uncertainty achieved on the ne=nm prediction needed for a nm-ne oscillation search ranges from 4% to 7%, whereas the overall normalization uncertainty on this ratio is 4.2%

Precision measurement of scaled momentum, charged multiplicity, and thrust in νμ and anti-νμ interactions

We report the first precision measurements of the scaled momentum, the charge multiplicity, and the thrust of hadronic jets in the Breit frame in Deep Inelastic Scattering n N and n N charged current events over the Q2 range from 1 to 100 m m GeV2. The neutrino data, obtained in the NOMAD experiment at the CERN SPS, extend the Q2-evolution of these parameters by two orders of magnitude, and with commensurate precision, when compared to those reported by the electron-proton and electron-positron experiments

A Study of Strange Particles Produced in νμ Neutral Current Interactions in the NOMAD experiment.

Results of a detailed study of strange particle production in neutrino neutral current interactions are presented using the data from the NOMAD experiment. Integral yields of neutral strange particles have been measured. Decays of resonances and heavy hyperons with an identified K0sor in the final state have been analyzed. Clear signals corresponding to K± and (1385)± have been observed. First results on the measurements of the polarization in neutral current interactions have been obtained

Bose–Einstein correlations in charged current muon–neutrino interactions in the NOMAD experiment at CERN

Bose–Einstein correlations in one and two dimensions have been studied, with high statistics, incharged current muon–neutrino interaction events collected with the NOMAD detector at CERN. In one dimension the Bose–Einstein effect has been analyzed with the Goldhaber and the Kopylov–Podgoretskii phenomenological parameterizations. The Goldhaber parameterization gives the radiusof the pion emission region RG = 1.01 ± 0.05(stat)+0.09 −0.06(sys) fm and for the chaoticity parameter the value λ = 0.40 ± 0.03(stat)+0.01−0.06(sys). Using the Kopylov–Podgoretskii parametrization yields RKP = 2.07 ± 0.04(stat)+0.01 −0.14(sys) fm and λKP = 0.29 ± 0.06(stat)+0.01 −0.04(sys). Different parameterizations of the long-range correlations have been also studied. The two-dimensional shape of the source has been investigated in the longitudinal comoving frame. A significant difference between the transverse and the longitudinal dimensions is observed. The high statistics of the collected sample allowed the study of the Bose–Einstein correlations as a function of rapidity, charged particle multiplicity and hadronic energy. A weak dependence of both radius and chaoticity on multiplicity and hadronic energy is found

Search for the exotic Θ+ resonance in the NOMAD experiment

A search for exotic Θ+ baryon via Θ+ →p+K0S decay mode in the NOMAD νμN data is reported. The special background generation procedure was developed. The proton identification criteria are tuned to maximize the sensitivity to the Θ+ signal as a function of xF which allows to study the Θ+ production mechanism. We do not observe any evidence for the Θ+ state in the NOMAD data. We provide an upper limit on Θ+ production rate at 90% CL as 2.13×10−3 per neutrino interaction

A search for νμ → ντ oscillations using the NOMAD detector

NOMAD is a neutrino oscillation experiment designed to search for neutrino-tau appearance in the CERN-SPS wide band beam. Signal detection relies on the identification of neutrino charged current interactions using kinematic criteria. The analysis the 1995 data sample yields no oscillation signal. Combining all studied tau decay modes, limit on the oscillation parameters are given

Search for a new gauge boson in neutral pion decays

A search was made for a new light gauge boson X which might be produced decay from neutral pions generated by 450 GeV protons in the CERN SPS neutrino target. The X’s would penetrate the downstream shielding and be observed in the NOMAD detector via the Primakoff effect. 20 candidate events with energy between 8 and 140 GeV were found from the analysis of neutrino data. This number is in agreement with the expectation of 18. background events from standard neutrino processes

A more sensitive search for neutrino(muon) to neutrino(tau) oscillations in NOMAD

With additional data and improved algorithms, we have enhanced the sensitivity of our appearance search for nu(mu) to nu(tau) oscillations in the NOMAD detector in the CERN-SPS wide-band neutrino beam. The search uses kinematic criteria to identify charged current interactions followed by decay of the tau to one of several decay modes. Our ‘‘blind’’ analyses of deep-inelastic scattering data taken in 1996 and 1997, combined with consistent reanalyses of previously reported 1995 data, yield no oscillation signal. For the two-family oscillation scenario, we present the contour outlining a 90% C.L. confidence region in the oscillation parameters 3.5 times more stringent than in our previous publication

A precise measurement of the muon neutrino-nucleon inclusive charged current cross section off an isoscalar target in the energy range 2.5 < E(nu) < 40 GeV by NOMAD

We present a measurement of the muon neutrino–nucleon inclusive charged current cross section, off an isoscalar target, in the neutrino energy range 2.5 Eν 40 GeV. The significance of this measurement is its precision, ±4% in 2.5 Eν 10 GeV, and ±2.6% in 10 Eν 40 GeV regions, where significant uncertainties in previous experiments still exist, and its importance to the current and proposed long baseline neutrino oscillation experiments