Yes / A microstrip line-fed wideband printed antenna is presented for radio detection of partial discharge (PD). The novel simple structure antenna has compact size of 24 × 20 × 0.16 cm3 (0.28λs × 0.23 λs × 0.002 λs) and suitable for radiometric PD wireless sensor nodes, where λs is the wavelength of the lowest frequency of the band (i.e., 0.35 GHz). The stepped and beveled radiation patch is used in combination with a slotted ground plane to achieve a wide fractional bandwidth of 119% (0.35 to 1.38 12 GHz) for a return loss better than 10 dB. Good radiation pattern characteristics are obtained across the frequency band of interest. The match between simulated and experimental results suggests that the design is sound and robust.

GZK neutrino are interesting messenger particles since, if detected, they can transmit<p>us exclusive information about ultra-high energy processes in the Universe. These particles,<p>which hold energies above 10^16 eV, interact very rarely. Therefore, detectors of<p>several gigatons of matter are needed to discover them. The ARA detector is planned<p>and currently being constructed at the South Pole. It is designed to use the Askaryan<p>effect, the emission of radio waves from neutrino induced cascades in the South Pole ice,<p>to detect neutrino interactions. With antennas distributed in 37 stations in the ice, such<p>interactions can be observed in a volume of several hundred cubic kilometers. Currently<p>2 ARA stations have been deployed in the ice and are taking data since the beginning<p>of the year 2013.<p>The first part of this thesis summarizes the current theories concerning the GZK mechanism<p>and the Askaryan effect to explain the interest in GZK neutrinos and in the used<p>detection method.<p>In the second part the ARA detector is described and calibrations of different detector<p>parts are presented. In this work, the digitization chips have been calibrated concerning<p>their timing precision and signal amplitude. In this way a timing precision of 100 ps<p>between antennas could be achieved. Furthermore, the geometry of the antenna clusters<p>is determined by cuts based on external signals to allow for a proper radio vertex reconstruction.<p>In the third part of the thesis the development of methods to distinguish radio signals<p>from thermal noise are presented. Moreover, a reconstruction method, developed to determine<p>the position of radio sources, is described. With only two stations operational<p>a discovery of GZK neutrinos is not expected and in fact no signal candidate has been<p>found in the analysis of the data. A neutrino <p>ux limit is calculated. This limit is not<p>competitive yet with the current best limits, but very promising for the full ARA detector.<p>The work shows that after completion this detector is expected to be capable of a<p>neutrino discovery. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Plus d'un siècle après leur découverte, les rayons cosmiques continuent d'intriguer les physiciens. Le flux de ces particules d'origine extraterrestre décroît fortement en fonction de leur énergie. Au-delà de 1 PeV(10¹⁵ eV), le flux devient trop faible pour permettre la détection directe sur des échelles de temps raisonnables. Cependant, les cascades de particules secondaires créées après l'interaction des rayons cosmiques avec les constituants de l'atmosphère sont détectables depuis le sol, c'est la détection indirecte. A partir de 100 PeV, le nombre d'observations est trop faible pour estimer de manière précise la masse des rayons cosmiques et ainsi contraindre les modèles de mécanismes d'accélération, de propagation et de type de sources. La détermination de la composition est effectuée à l'Observatoire Pierre Auger par les télescopes de fluorescence via la mesure de la variable Xmax avec un cycle utile de 14%. Xmax est la profondeur d'atmosphère traversée à laquelle le nombre de particules secondaires atteint sa valeur maximale. Cette observable est fortement corrélée à la masse du rayon cosmique qui a initié la gerbe. Un grand nombre d'observations est requis pour effectuer une détermination précise de la masse car les fluctuations statistiques de Xmax sont importantes. La radio détection apparaît alors comme une excellente alternative à la détection par fluorescence, puisque la technique mesurant ce signal a un cycle utile proche de 100%. Cette thèse propose une méthode d'estimation de la masse des rayons cosmiques d'ultra haute énergie basée seulement sur l'étude des signaux radio et leur simulation, afin de reconstruire de manière systématique l’énergie, le cœur et la profondeur Xmax des gerbes détectées par l’expérience AERA sur le site de l'Observatoire Pierre Auger en Argentine. L'influence de la modélisation de l'atmosphère dans le code de simulation SELFAS sur les valeurs reconstruites est étudiée. Notamment la géométrie des couches atmosphériques, la manière de traiter l'indice de réfraction et la densité de l'air ainsi que leurs variations journalières et saisonnières. / More than a century after their discovery, cosmic-raysare still puzzling physicists. The flux of these particlescoming from extraterrestrial sources strongly decreasesas a function of their energy. Above 1 PeV (10¹⁵ eV), theparticle flux becomes too low to allow a direct detectionon a reasonable time scale. However, the cascades ofsecondary particles produced after the interaction ofcosmic-rays with the constituents of the atmosphere aredetectable at the ground level; it is the indirect detection.Above 100 PeV, the number of observations is too lowto accurately estimate the mass of the cosmic rays andthen to constrain the prediction models of accelerationmechanisms, propagation and type of sources. Thedetermination of their composition is achieved at thePierre Auger Observatory using fluorescencetelescopes from the measurement of the Xmaxobservable with a duty cycle of 14%. Xmax, defined asthe atmosphere depth at which the number ofsecondary particles reaches its maximal value, is highlycorrelated to the mass of the cosmic ray that hascreated the air shower. A large number of observationsis required for a precise estimation of the mass as theXmax statistical fluctuations are important. The radiodetection is a perfect alternative to the fluorescencemethod as the duty cycle of a typical radio detector isclose to 100%. This thesis proposes a method toestimate the mass of ultra-high energy cosmic raysusing only the radio signals and their simulation. Thegoal is to systematically reconstruct the Xmax depth ofeach air shower detected by the AERA experimentwithin the site of the Pierre Auger Observatory inArgentina. The influence of the description of theatmosphere on the reconstructed shower parameters, inthe SELFAS code, has been studied. It includes thegeometry of the atmospheric layers, the way to calculatethe air refractive index and density, as well as their dailyand seasonal fluctuations.

The detection of high-energy neutrinos in the E &gt; O(PeV) range requires newdetection techniques in order to cope with the decreasing flux. The radio detectionmethod uses Askaryan emission to detect these neutrinos. The propagation of theradio pulses has to be modeled carefully in order to estimate the properties of theneutrinos from the detected radio pulse. This report introduces a model whichwas implemented to the NuRadioMC code to simulate birefringence effects in theice of the South Pole. To do that, a new ice model was created which combinesthe density and directional dependence on the refractive index. With this icemodel and an analytical ray tracer the time delay and polarization resulting frombirefringence was simulated for different geometries. A directional dependenceon the magnitude of the time delay and the change of the polarization along thepropagation path was found. To model the mixing of the polarization states dueto this change in polarization a pulse propagation model was introduced. Timedelay calculations resulting from this model were compared to simulations andmeasurements from the ARA experiment and have shown good agreement.

No description available.

Après plus d'un siècle d'études, l'origine des rayons cosmiques d’ultra-haute énergie reste mal comprise. En améliorant la connaissance de la composition des rayons cosmiques détectés sur Terre, il est possible de contraindre les modèles concernant leur origine, ainsi que leur mécanisme de production dans les sources astrophysiques. Les simulations montrent que le champ électrique émis par les gerbes est sensible à leur développement dans l'atmosphère. Ce champ électrique peut être mesuré avec un cycle utile élevé, faisant du signal radio une observable prometteuse pour identifier le rayon cosmique primaire. Le signal radio permet également de mesurer sa direction d'arrivée et son énergie. Depuis 2006, l'observatoire Pierre Auger accueille plusieurs réseaux de radio détection des rayons cosmiques. Des démonstrateurs équipés de quelques stations (RAuger,MAXIMA) ont permis une caractérisation efficace de l'environnement radio du site, ils ont également apporté des contraintes sur les mécanismes responsables de l'émission du champ électrique par les gerbes dans le domaine du MHz. Les prototypes ont mené à la construction d’AERA (Auger Engineering Radio Array) qui, avec 124 stations couvrant 6 km², est le premier réseau grande échelle de radio détection des gerbes dans le domaine du MHz. AERA est déployé dans l'extension basse énergie de l'observatoire afin de bénéficier d'une statistique plus importante. Le réseau permet d'intéressantes mesures hybrides ; son emplacement permet en effet de croiser les données obtenues par la radio avec celles provenant du réseau de surface (SD) et des télescopes à fluorescence (FD) proches du réseau. Cette thèse est dédiée à la caractérisation de signaux transitoires radio détectés par RAuger et AERA. Comme un des défis de la radio détection des gerbes atmosphériques est de supprimer les bruits de fond anthropiques causant des déclenchements accidentels, des méthodes de réjection du bruit de fond et de sélection des coïncidences SD-AERA ont été développées. Une étude de la corrélation entre le développement de la gerbe dans l'atmosphère (profil longitudinal) et le champ électrique mesuré par les stations radio est également présentée. Cette étude valide le lien direct entre le champ électrique et le développement de la gerbe dans l'atmosphère et confirme l’intérêt du signal radio pour l’estimation de la nature des rayons cosmiques d'ultra-haute énergie. / After more than a century of studies, one of the challenging questions related to ultra-high energy cosmic rays concerns their nature, which remains unclear. Improving the knowledge about the composition of cosmic rays will permit to constrain the models concerning their origins and the production mechanisms in the astrophysical sources. Simulations show that, the electric field emitted by the shower is sensitive to its development. This electric-field can be measured with a high duty cycle, and thus is apromising technique to identify an observable sensitive to the nature of the primary cosmic ray. The radio signal is also used to measure its arrival direction and its energy. Since 2006, the Pierre Auger Observatory hosts several radio detection arrays of cosmic rays, starting from small size prototypes (RAuger, MAXIMA) to achieve a large scale array of 124 radio stations: AERA, the Auger Engineering Radio Array covering 6 km². These different arrays allow the study of the radio emission during the development of the shower in the MHz domain. AERA is deployed in the low energy extension of the Pierre Auger Observatory in order to have a larger statistics. It enables interesting hybrid measurements, with the comparison of radio observable with those obtained with the surface detector (SD) and the fluorescence telescopes close to the array. This thesis is dedicated to the characterization of the radio transient signals detected by RAuger and AERA. As one of the challenges of the radio detection of air-shower is to remove the anthropic background causing accidental triggering, methods for background rejection and SD-AERA coincidences selection have been developed. A study of the correlation between the shower development in the atmosphere (longitudinal profile) and the electric-field measured by the radio stations is also presented. This study shows the relationship between the electric-field and the shower development in the atmosphere and confirms that the radio signal is a powerful tool to study the nature of the ultra-high energy cosmic rays.

Simulations have demonstrated that high-energy neutrinos (E &gt; 1017 eV) are detected cost-efficiently via the Askaryan effect in ice, where a particle cascade induced by the neutrino interaction produces coherent radio emission that can be picked up by antennas installed below the surface. A good knowledge of the near surface ice (aka firn) properties is required to reconstruct the neutrino properties. In particular, a continuous monitoring of the snow accumulation (which changes the depth of the antennas) and the index-of-refraction profile are crucial for an accurate determination of the neutrino's direction and energy. 14 months of data of the ARIANNA detector on the Ross Ice Shelf, Antarctica, are presented where a prototype calibration system was successfully used to monitor the snow accumulation with unprecedented precision of 1 mm. Several algorithms to extract the time differences of direct and reflected (off the surface) signals (D'n'R time difference) from noisy data (including deep learning) are explored. This constitutes an in-situ test of the neutrino vertex distance reconstruction using the D'n'R technique which is needed to determine the neutrino energy. Additionally, an in-situ calibration system is proposed that extends the radio detector station with a radio emitter to continuously monitor the firn properties by measuring D'n'R time difference. In a simulation study the station layout is optimized and the achievable precision is quantified.

High-energy neutrino physics offers a unique way to investigate the most violent phenomena in our universe. The detection of energies above E &gt; 1017 eV is most efficient using the Askaryan effect, where a neutrino-induced particle shower produces coherent radio emission that is detectable with radio antennas. By using radio techniques large volumes can be covered with few stations at moderate cost exploiting the large attenuation length of radio in cold ice. Key to the reconstruction of the neutrino properties visa precise and continuous monitoring of the firn properties. In particular the snow accumulation (changing the absolute depth of the antennas thus the propagation path of the signal) and the index-of-refraction profile are crucial for the neutrino energy and direction reconstruction. This work presents an in-situ calibration design that acts as an detector extension by adding additional emitter antennas to the station design to continuously monitor the firn properties by measuring the direct and reflected signals (D’n’R). In a simulation study the optimal station layout is determined and the achievable precision is quantified. Furthermore 14 months of data from an ARIANNA station at the Ross Ice Shelf, Antarctica, are presented where a prototype of this calibration system has been successfully installed to monitor the snow accumulation with unprecedented precision of 1 mm. Several algorithms, including deep learning algorithms, to compute the D’n’R time difference from radio traces are considered.

Malgré la découverte des rayons cosmiques il y a plus de cent ans, de nombreuses questions restent aujourd’hui sans réponse : que sont les rayons cosmiques, comment sont-ils créés et d’où viennent-ils ? Depuis 2002, l’instrument CODALEMA, basé sur le site de l’Observatoire de radio-astronomie de Nançay, étudie les rayons cosmiques d’ultra haute énergie (RCUHE, au delà de 1017 eV) qui arrivent dans l’atmosphère terrestre. Leur faible flux rend impossible une détection directe à ces énergies. Ces rayons cosmiques vont cependant interagir avec les atomes de l’atmosphère, engendrant une cascade de particules secondaires chargées communément appelée gerbe de particules, détectable depuis le sol, et dont on va extraire des informations sur le rayon cosmique primaire. L’objectif est de remonter aux caractéristiques du primaire ayant engendré la gerbe de particules, donc de déterminer sa direction d’arrivée, sa nature et son énergie. Lors du développement de la gerbe, les particules chargées en mouvement engendrent notamment l’émission d’une impulsion de champ électrique très brève, que CODALEMA détecte au sol avec des antennes radio dédiées, sur une large bande de fréquences (entre 1 et 200 MHz). L’avantage majeur de la radio-détection est sa sensibilité au profil complet de la gerbe et son cycle utile proche des 100 %, qui pourrait permettre d’augmenter le nombre d’évènements détectés à très haute énergie, et donc de mieux contraindre les propriétés des RCUHE. Au fil des ans, des efforts importants ont été consacrés à la compréhension de l’émission radio-électrique des grandes gerbes de particules dans la gamme [20-80] MHz mais, malgré certaines études menées jusqu’aux années 90, la bande [1-10] MHz est restée inutilisée pendant près de 30 ans. L’une des contributions de cette thèse porte sur l’expérience EXTASIS, adossée à CODALEMA, qui vise à ré-investiguer cette bande et à étudier la contribution dite de ”mort subite”, impulsion de champ électrique créé par les particules de la gerbe lors de leur arrivée et de leur disparition au sol. Nous présentons la configuration instrumentale d’EXTASIS, composée de 7 antennes basses fréquences exploitées dans [1.7-3.7] MHz, couvrant environ 1 km2. Nous rapportons l’observation, sur 2 ans, de 25 évènements détectés en coïncidence par CODALEMA et EXTASIS et estimons un seuil de détection de 23±4 μV/m à partir de comparaisons avec des simulations. Nous rapportons également une forte corrélation entre l’observation du signal basse fréquence et le champ électrique atmosphérique. L’autre contribution majeure de cette thèse porte sur l’étude du champ électrique émis par les gerbes et l’amélioration des performances du détecteur dans la bande [20-200] MHz. Nous proposons dans un premier temps une méthode de calibration des antennes de CODALEMA en utilisant l’émission radio de la Galaxie. Nous investiguons aussi plusieurs algorithmes de réjection de bruit afin d’améliorer la sélectivité des évènements enregistrés. Nous présentons ensuite une méthode de reconstruction des paramètres du rayon cosmique primaire, mettant en oeuvre des comparaisons combinant des informations de polarisation et fréquentielles entre les données enregistrées et des simulations, nous menant enfin à une proposition de composition en masse des rayons cosmiques détectés. / Despite the discovery of cosmic rays there are more than one hundred years ago, many questions remain unanswered today: what are cosmic rays, how are they created and where do they come from ? Since 2002, the CODALEMA instrument, located within the Nançay Radio Observatory, studies the ultra-high energy cosmic rays (UHECR, above 1017 eV) arriving in the Earth atmosphere. Their low flux makes it impossible to detect them directly at these energies. These cosmic rays, however, will interact with the atoms of the atmosphere, generating a cascade of secondary charged particles, commonly known as extensive air shower (EAS), detectable at ground level, and from which we will extract information on the primary cosmic ray. The objective is to go back to the characteristics of the primary that generated the EAS, thus to determine its direction of arrival, its nature and its energy. During the development of the shower, these charged particles in movement generate a fast electric field transient, detected at ground by CODALEMA with dedicated radio antennas over a wide frequency band (between 1 and 200 MHz). The major advantage of radio-detection is its sensibility to the whole profile of the shower and its duty cycle close to 100 %, which could increase the number of events detected at very high energy, and thus to better constrain the properties of the RCUHE. Over the years, significant efforts have been devoted to the understanding of the radio emission of extensive air shower (EAS) in the range [20-80] MHz but, despite some studies led until the nineties, the[1-10] MHz band has remained unused for nearly 30 years. One of the contributions of this thesis concerns the EXTASIS experiment, supported by the CODALEMA instrument, which aims to reinvestigate the [1-10] MHz band and to study the so-called ”sudden death” contribution, which is the expected impulsive electric field created by the particles at their arrival and their disappearance on the ground. We present the instrumental set up of EXTASIS, composed of 7 low frequency antennas exploited in [1.7-3.7] MHz, covering approximately 1 km2. We report the observation, over 2 years, of 25 low-frequency events detected in coincidence by CODALEMA and EXTASIS and estimate a detection limit of 23±4 μV/m from comparisons with simulations. We also report a strong correlation between the observation of the low frequency signal and the atmospheric electric field. The other major contribution of this thesis concerns the study of the electric field emitted by the EAS and the improvement of the detector’s performances in the [20-200] MHz band. First, we propose a calibration method for CODALEMA antennas using the radio emission of the Galaxy. We are also investigating several noise rejection algorithms to improve the selectivity of recorded events. We then present a method for reconstructing the parameters of the primary cosmic ray, implementing systematic comparisons combing polarization and frequency information between the recorded data and simulations, leading finally to a proposal for a mass composition of cosmic rays detected.

Artificial intelligence (AI) and deep learning have made a full impact on society the last decades, including the realm of particle physics. This thesis explores whether a neural network, a deep learning program mimicking the biological brain, can be used to reject noise in real time at the Radio Neutrino Observatory in Greenland (RNO-G). RNO-G aims to detect radio waves in the ice cape of Greenland, induced by ultra high energy neutrinos ($&gt;10^{18}$ eV). Due to the low flux of neutrinos at these energies, it is desired to increase the sensititivty of RNO-G by lowering the trigger threshold as much as possible. However, lowering the threshold is currently limited by unavoidable thermal noise fluctuations that would otherwise saturate the detector. Previous research has shown that a neural network could be used on a similar neutrino detector, ARIANNA, to reject thermal noise in real time, thus making it possible to lower the trigger threshold below the noise floor. This thesis aims to do the same for RNO-G.