36 research outputs found
The Drift Chambers Of The Nomad Experiment
We present a detailed description of the drift chambers used as an active
target and a tracking device in the NOMAD experiment at CERN. The main
characteristics of these chambers are a large area, a self supporting structure
made of light composite materials and a low cost. A spatial resolution of 150
microns has been achieved with a single hit efficiency of 97%.Comment: 42 pages, 26 figure
Inclusive production of and mesons in charged current interactions
The inclusive production of the meson resonances ,
and in neutrino-nucleus charged current interactions has been
studied with the NOMAD detector exposed to the wide band neutrino beam
generated by 450 GeV protons at the CERN SPS. For the first time the
meson is observed in neutrino interactions. The statistical
significance of its observation is 6 standard deviations. The presence of
in neutrino interactions is reliably established. The average
multiplicity of these three resonances is measured as a function of several
kinematic variables. The experimental results are compared to the
multiplicities obtained from a simulation based on the Lund model. In addition,
the average multiplicity of in antineutrino - nucleus
interactions is measured.Comment: 23 pages, 14 figures, 8 tables. To appear in Nucl. Phys.
Search for heavy neutrinos mixing with tau neutrinos
We report on a search for heavy neutrinos (\nus) produced in the decay
D_s\to \tau \nus at the SPS proton target followed by the decay \nudecay in
the NOMAD detector. Both decays are expected to occur if \nus is a component
of .\
From the analysis of the data collected during the 1996-1998 runs with
protons on target, a single candidate event consistent with
background expectations was found. This allows to derive an upper limit on the
mixing strength between the heavy neutrino and the tau neutrino in the \nus
mass range from 10 to 190 . Windows between the SN1987a and Big Bang
Nucleosynthesis lower limits and our result are still open for future
experimental searches. The results obtained are used to constrain an
interpretation of the time anomaly observed in the KARMEN1 detector.\Comment: 20 pages, 7 figures, a few comments adde
The NOMAD Experiment at the CERN SPS
The NOMAD experiment is a short base-line search for ν<sub>μ</sub> − ν<sub>τ</sub> oscillations in the CERN neutrino beam. The ν<sub>τ</sub>'s are searched for through their charged current interactions followed by the observation of the resulting τ− through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction and individual particles is demonstrated through the ability of NOMAD to observe K<sub>s</sub><sup>0</sup>'s, Λ<sup>0</sup>'s and π<sup>0</sup>'s. Finally, the observation of τ− through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed
The NOMAD experiment at the CERN SPS
The NOMAD experiment is a short base-line search for oscillations in the CERN neutrino beam. The 's are searched for through their charged-current interactions followed by the observation of the resulting through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors, and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction of individual particles is demonstrated through the ability of NOMAD to observe K's, 's and 's. Finally, the observation of through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed
Search for a new gauge boson in decays
A search was made for a new light gauge boson which might be produced in
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, in the process
of conversion in the external Coulomb field of a nucleus. With
protons on target, 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 18.12.8 background
events from standard neutrino processes. A new 90% C.L. upper limit on the
branching ratio for
masses ranging from 0 to 120 MeV/c^2 is obtained.Comment: 15 pages, LaTex, 6 eps figures included, submitted to Physics Letters
DIANE multiparticle transport code
DIANE is the general Monte Carlo code developed at CEA-DAM. DIANE is a 3D multiparticle multigroup code. DIANE includes automated biasing techniques and is optimized for massive parallel calculations
MEASUREMENT OF THE ANTI-LAMBDA POLARIZATION IN MUON-NEUTRINO CHARGED CURRENT INTERACTIONS IN THE NOMAD EXPERIMENT
We present a measurement of the polarization of )over bar> hyperons produced in nu (mu) charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same V-0 identification procedure and analysis method reported in a previous paper [NOMAD Collaboration. Nucl. Phys. B 588 (2000) 3] for the case of Lambda hyperons. The )over bar> polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero