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AbstractAbstract
[en] The understanding on the ultra high energy cosmic rays (E > 1018 eV) issue has been improved over the last decade, especially through the noteworthy results of the Pierre Auger Observatory. The composition of cosmic rays at those energies is still an open matter. The EASIER project (Extensive Air Shower Identification using Electron Radiometer) on radio detection of extensive air showers is looking for new observables related to the nature of primary cosmic rays, complementary to those already implemented at the Pierre Auger Observatory. This prototype consists of an array of MHz and GHz antennas, set up on a slave mode on about sixty tanks of the surface detector of the Observatory. Further to a study of the antenna response and a data analysis, the features of the detected signals at MHz frequencies have turned out to be compatible with a geomagnetic origin of the shower radio emission. At GHz frequencies, only a few signals have been detected in coincidence with extensive air showers. A simulation program has been created, aiming to identify the origin of this microwave emission. It includes the air shower development in the atmosphere and different emission mechanisms at GHz frequencies: the Cerenkov radiation and the molecular Bremsstrahlung. The radiation propagation through the atmosphere and the receiving antenna response are simulated as well, allowing to directly compare the detected signals to the predicted ones. (author)
[fr]
Les connaissances sur les rayons cosmiques d'ultra haute energie (E > 1018 eV) ont progresse durant la derniere decennie, en particulier grace aux resultats remarquables de l'Observatoire Pierre Auger. La question de la composition du flux de rayons cosmiques a ces energies reste cependant ouverte. Le projet EASIER (Extensive Air Shower Identification using Electron Radiometer) de detection radio des gerbes atmospheriques recherche de nouvelles observables liees a la nature du rayonnement cosmique primaire, complementaires de celles deja mise en oeuvre a l'Observatoire Pierre Auger. Ce dispositif est constitue d'un reseau d'antennes radio fonctionnant aux frequences MHz et GHz et installees en mode esclave sur une soixantaine de detecteurs de particules du reseau de surface de l'Observatoire. Apres etude de la reponse des detecteurs et analyse des donnees, les caracteristiques des signaux detectes aux frequences MHz se sont revelees compatibles avec une origine geomagnetique de l'emission radio des gerbes. Aux frequences GHz, seuls quelques signaux ont ete detectes en coincidence avec des gerbes atmospheriques. Un programme de simulation a ete realise dans le but d'identifier l'origine de cette emission micro-ondes. Il inclut le developpement de la gerbe dans l'atmosphere et differents mecanismes d'emission aux frequences GHz: l'effet Cerenkov et le bremsstrahlung moleculaire. La propagation du rayonnement dans l'atmosphere et la reponse de l'antenne receptrice sont egalement simules, ce qui permet une comparaison directe des signaux detectes avec les signaux attendus. (auteur)Original Title
Radiodetection des gerbes atmospheriques a l'Observatoire Pierre Auger
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14 Oct 2014; 240 p; 175 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: Physique subatomique et astroparticules
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Miscellaneous
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ANISOTROPY, ANTENNAS, BREMSSTRAHLUNG, CALIBRATION, CHERENKOV RADIATION, COINCIDENCE METHODS, COMPUTERIZED SIMULATION, COSMIC RADIO SOURCES, COSMIC RAY DETECTION, ELECTRIC IMPEDANCE, ELECTRON TEMPERATURE, ENERGY SPECTRA, EXTENSIVE AIR SHOWERS, GAIN, GHZ RANGE, MHZ RANGE, MICROWAVE RADIATION, RADIOMETERS, REFRACTIVE INDEX
AMPLIFICATION, COSMIC RADIATION, COSMIC SHOWERS, COUNTING TECHNIQUES, DETECTION, ELECTRICAL EQUIPMENT, ELECTROMAGNETIC RADIATION, EQUIPMENT, FREQUENCY RANGE, IMPEDANCE, IONIZING RADIATIONS, MEASURING INSTRUMENTS, OPTICAL PROPERTIES, PHYSICAL PROPERTIES, RADIATION DETECTION, RADIATION DETECTORS, RADIATIONS, SECONDARY COSMIC RADIATION, SHOWERS, SIMULATION, SPECTRA
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