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AbstractAbstract
[en] Nearly one century after their discovery, cosmic rays are still subject to many questions. In particular at ultra-high energy (UHE) where their nature, origin and production mechanism are still unknown despite numerous experimental advances. The Pierre Auger observatory is currently the key experiment to try to answer these questions. In this context, the search for UHE neutrinos remains a major challenge for astroparticle physics. Their study is likely to bring information that are still missing to the ultra-high energy cosmic ray puzzle regarding their origin and production mechanism. This thesis focuses on the search for UHE neutrinos at the Pierre Auger observatory and particularly on neutrinos arriving below the horizon (i.e. earth skimming) and interacting in the earth crust. In a first part, the phenomenological and experimental context is introduced. In a second part, we first present our study of systematic uncertainties on interactions models of UHE neutrinos and tau lepton through a revisited analysis of earth skimming tau neutrinos in the context of the combination of the results of the different observatory's detection channels. This combination allowed to put a competitive limit on the UHE neutrinos flux, beyond the Waxman and Bachal limit. We will then show our work on earth skimming electron neutrinos. They produce, by interacting in the earth crust, underground electromagnetic showers subject to the LPM (Landau, Pomeranchuk and Migdal) effect which causes a delay in their development and increase their detection probability. A complete simulation chain of this channel was developed in order to estimate the sensitivity of the observatory to such events. Finally, in the context of proposals to upgrade the observatory in order to improve its performance beyond 2015, we present the study we have performed about the impact of a new acquisition electronic and new triggers on the earth skimming neutrinos detection efficiency by the stations of the ground array. (author)
[fr]
Pres d'un siecle apres leur decouverte, les rayons cosmiques sont encore sujets a de nombreuses interrogations. A ultra-haute energie (UHE), leur nature, leur origine et leur mecanisme de production restent encore inconnus malgre les avancees experimentales. L'observatoire Pierre Auger est actuellement l'experience incontournable pour tenter de repondre a ces questions. Dans ce contexte, l'etude et la recherche de neutrinos a UHE sont susceptibles d'apporter des informations encore manquantes au puzzle des rayons cosmiques d'ultra-haute energie, notamment quant a leur mecanisme de production ou leur origine. C'est dans ce cadre que s'inscrit cette these, centree sur la recherche de neutrinos a UHE a l'observatoire Pierre Auger et plus particulierement sur l'etude des neutrinos arrivant sous l'horizon (i.e. a incidence rasante) et interagissant dans la croute terrestre. Dans une premiere partie, le contexte phenomenologique et experimental dans lequel s'inscrit cette these est introduit. Dans une seconde partie, nous presenterons tout d'abord notre etude des incertitudes systematiques sur les modeles d'interactions a UHE des neutrinos et des leptons tau a travers une analyse revisitee des neutrinos tau a incidence rasante. Cette etude s'inscrit dans le cadre de la combinaison des resultats des differents canaux de detection de l'observatoire qui a permis de poser une limite competitive sur les flux de neutrinos a UHE, au dela de la limite de Waxman et Bahcall. Nous presenterons ensuite notre travail effectue sur les neutrinos electroniques a incidence rasante. Ces derniers engendrent, en interagissant dans la croute terrestre, des gerbes electromagnetiques souterraines soumises a l'effet LPM (Landau, Pomeranchuk et Migdal) qui entraine un retard de leur developpement et augmente leur probabilite de detection. Une chaine complete de simulation de ce canal a ete developpee afin d'evaluer la sensibilite de l'observatoire a ces evenements. Enfin, dans le cadre de propositions d'ameliorations de l'observatoire en vue d'accroitre ses performances a partir de 2015, nous presentons l'etude que nous avons effectuee sur l'impact d'une nouvelle electronique d'acquisition et de nouveaux modes de declenchements sur l'efficacite de detection des neutrinos a incidence rasante par les stations du reseau au sol. (auteur)Original Title
Etude des neutrinos d'ultra-haute energie a l'observatoire Pierre Auger
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30 Sep 2013; 245 p; 218 refs.; Available from the INIS Liaison Officer for France, see the INIS website for current contact and E-mail addresses; These Docteur de l'Universite de Grenoble, Specialite: Astroparticules
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Miscellaneous
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CALIBRATION, CHERENKOV COUNTERS, COSMIC NEUTRINOS, COSMIC SHOWERS, CROSS SECTIONS, ELECTRON NEUTRINOS, FLUORESCENCE, INCIDENCE ANGLE, MONTE CARLO METHOD, NEUTRINO DETECTION, NEUTRINO DETECTORS, NEUTRINO OSCILLATION, NUCLEAR FACILITIES, PHOTON-ELECTRON INTERACTIONS, PHOTONUCLEAR REACTIONS, SENSITIVITY, TAU PARTICLES, TRIGGER CIRCUITS
CALCULATION METHODS, COSMIC RADIATION, DETECTION, ELECTRONIC CIRCUITS, ELEMENTARY PARTICLES, EMISSION, FERMIONS, HEAVY LEPTONS, INTERACTIONS, IONIZING RADIATIONS, LEPTONS, LUMINESCENCE, MASSLESS PARTICLES, MEASURING INSTRUMENTS, NEUTRINOS, NUCLEAR REACTIONS, PARTICLE INTERACTIONS, PHOTON EMISSION, PHOTON-LEPTON INTERACTIONS, PULSE CIRCUITS, RADIATION DETECTION, RADIATION DETECTORS, RADIATIONS, SECONDARY COSMIC RADIATION, SHOWERS
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