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AbstractAbstract
[en] This work has been achieved within the ALEPH experiment installed on the electron-positron collider LEP at CERN, in order to determine the number of light neutrino species, a free parameter of the Standard model. To perform the measurements, a method based on single photon final states is chosen, where neutrino-antineutrino pair is undetected. The cross-section of such a process is almost proportional to the number of neutrino species. Such events are selected according to criteria which reject background not coming from electron-positron interactions. Other background contributions have been estimated using detailed simulations. The signal-background separation is improved by a maximum of likelihood method. From the signal cross-section, a number of neutrino species of 2.65 ± 2*(0.20) is derived
Original Title
Mesure de la section efficace de photons uniques avec le detecteur Aleph: determination du nombre de neutrinos
Primary Subject
Source
Oct 1992; 159 p; These (D. es Sc.).
Record Type
Report
Literature Type
Thesis/Dissertation
Report Number
Country of publication
ANTILEPTONS, ANTIMATTER, ANTINEUTRINOS, ANTIPARTICLES, COINCIDENCE METHODS, COLLISIONS, COUNTING TECHNIQUES, DETECTION, ELECTRON COLLISIONS, ELEMENTARY PARTICLES, FERMIONS, FIELD THEORIES, GRAND UNIFIED THEORY, INTERACTIONS, LEPTONS, MASSLESS PARTICLES, MATHEMATICAL MODELS, MATTER, MEASURING INSTRUMENTS, NEUTRINOS, NOISE, PARTICLE INTERACTIONS, PARTICLE MODELS, PARTICLE PRODUCTION, PHOTON-LEPTON INTERACTIONS, POSITRON COLLISIONS, QUANTUM FIELD THEORY, RADIATION DETECTION, RADIATION DETECTORS, STORAGE RINGS, UNIFIED GAUGE MODELS
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