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.

No description available.

No description available.

<p>A search for a diffuse flux of cosmic neutrinos with energies in excess of 10¹⁴ eV was performed using two years of AMANDA-II data, collected in 2003 and 2004. A 20% evenly distributed sub-sample of experimental data was used to verify the detector description and the analysis cuts. A very good agreement between this 20% sample and the background simulations was observed. The analysis was optimised for discovery, to a relatively low price in limit setting power. The background estimate for the livetime of the examined 80% sample is 0.035 ± 68% events with an additional 41% systematical uncertainty.</p><p>The total neutrino flux needed for a 5σ discovery to be made with 50% probability was estimated to 3.4 ∙ 10^-7 <i>E</i>^-2 GeV s^-1 sr^-1 cm^-2 equally distributed over the three flavours, taking statistical and systematic uncertainties in the background expectation and the signal efficiency into account. No experimental events survived the final discriminator cut. Hence, no ultra-high energy neutrino candidates were found in the examined sample. A 90% upper limit is placed on the total ultra-high energy neutrino flux at 2.8 ∙ 10^-7 <i>E</i>^-2 GeV s^-1 sr^-1cm^-2, taking both systematical and statistical uncertainties into account. The energy range in which 90% of the simulated <i>E</i>^-2signal is contained is 2.94 ∙ 10¹⁴ eV to 1.54 ∙ 10¹⁸eV (central interval), assuming an equal distribution over the neutrino flavours at the Earth. The final acceptance is distributed as 48% electron neutrinos, 27% muon neutrinos, and 25% tau neutrinos.</p><p>A set of models for the production of neutrinos in active galactic nuclei that predict spectra deviating from <i>E</i>^-2 was excluded.</p>

The master's thesis is dedicated to studying the propagation of ultra-high energy proton cosmic rays under a hypothesis of Lorentz invariance violation. For this purpose, numerical methods were used. Our calculations indicated that the ef- fective horizon of ultra-high energy cosmic protons is significantly extended when Lorentz invariance violation is assumed. Further, we investigated the effects of Lo- rentz invariance violation on the Cosmic ray spectrum. We learned that measured cosmic ray spectra are a suitable tool for constraining the coefficients describing Lorentz invariance violation and we estimated an interval where the upper bound on the pion Lorentz invariance violating coefficient lies. Moreover, a correlation between free parameters of the analytical model of cosmic ray spectrum and coefficients, that describes Lorentz invariance violation, was found.

A search for a diffuse flux of cosmic neutrinos with energies in excess of 1014 eV was performed using two years of AMANDA-II data, collected in 2003 and 2004. A 20% evenly distributed sub-sample of experimental data was used to verify the detector description and the analysis cuts. A very good agreement between this 20% sample and the background simulations was observed. The analysis was optimised for discovery, to a relatively low price in limit setting power. The background estimate for the livetime of the examined 80% sample is 0.035 ± 68% events with an additional 41% systematical uncertainty. The total neutrino flux needed for a 5σ discovery to be made with 50% probability was estimated to 3.4 ∙ 10-7 E-2 GeV s-1 sr-1 cm-2 equally distributed over the three flavours, taking statistical and systematic uncertainties in the background expectation and the signal efficiency into account. No experimental events survived the final discriminator cut. Hence, no ultra-high energy neutrino candidates were found in the examined sample. A 90% upper limit is placed on the total ultra-high energy neutrino flux at 2.8 ∙ 10-7 E-2 GeV s-1 sr-1 cm-2, taking both systematical and statistical uncertainties into account. The energy range in which 90% of the simulated E-2 signal is contained is 2.94 ∙ 1014 eV to 1.54 ∙ 1018 eV (central interval), assuming an equal distribution over the neutrino flavours at the Earth. The final acceptance is distributed as 48% electron neutrinos, 27% muon neutrinos, and 25% tau neutrinos. A set of models for the production of neutrinos in active galactic nuclei that predict spectra deviating from E-2 was excluded.

Près d'un siècle après leur découverte, les rayons cosmiques sont encore sujets à de nombreuses interrogations. À ultra-haute énergie (UHE), leur nature, leur origine et leur mécanisme de production restent encore inconnus malgré les avancées expérimentales. L'observatoire Pierre Auger est actuellement l'expérience incontournable pour tenter de répondre à ces questions. Dans ce contexte, l'étude et la recherche de neutrinos à UHE sont susceptibles d'apporter des informations encore manquantes au puzzle des rayons cosmiques d'ultra-haute énergie, notamment quant à leur mécanisme de production ou leur origine. C'est dans ce cadre que s'inscrit cette thèse, centrée sur la recherche de neutrinos à UHE à l'observatoire Pierre Auger et plus particulièrement sur l'étude des neutrinos arrivant sous l'horizon (i.e. à incidence rasante) et interagissant dans la croûte terrestre. Dans une première partie, le contexte phénoménologique et expérimental dans lequel s'inscrit cette thèse est introduit. Dans une seconde partie, nous présenterons tout d'abord notre étude des incertitudes systématiques sur les modèles d'interactions à UHE des neutrinos et des leptons tau à travers une analyse revisitée des neutrinos tau à incidence rasante. Cette étude s'inscrit dans le cadre de la combinaison des résultats des différents canaux de détection de l'observatoire qui a permis de poser une limite compétitive sur les flux de neutrinos à UHE, au delà de la limite de Waxman et Bahcall. Nous présenterons ensuite notre travail effectué sur les neutrinos électroniques à incidence rasante. Ces derniers engendrent, en interagissant dans la croûte terrestre, des gerbes électromagnétiques souterraines soumises à l'effet LPM (Landau, Pomeranchuk et Migdal) qui entraîne un retard de leur développement et augmente leur probabilité de détection. Une chaîne complète de simulation de ce canal a été développée afin d'évaluer la sensibilité de l'observatoire à ces évènements. Enfin, dans le cadre de propositions d'améliorations de l'observatoire en vue d'accroître ses performances à partir de 2015, nous présentons l'étude que nous avons effectuée sur l'impact d'une nouvelle électronique d'acquisition et de nouveaux modes de déclenchements sur l'efficacité de détection des neutrinos à incidence rasante par les stations du réseau au sol. / 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 informations 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 uncertainies 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) effet which causes a delay in their development and increaase 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.

Orientador: Prof. Dr. Marcelo Augusto Leigui de Oliveira / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Física, 2016. / We present in this work studies on ultra-high energy cosmic rays using the air- uorescence detection technique. The research main objective consists in event reconstructions from a fluorescence telescope, such that a simulation code has been developed taking into account the physical processes involved in the generation and the propagation of uorescence photons from an extensive air shower to a telescope. The secondary particles of air showers has been previously obtained using CORSIKA code for dierent primary energies and compositions. Furthermore, the photon generation has been calculated using Bethe and Bloch equation for the energy loss of electrons and positrons in air and the uorescence yield parameterized with air conditions at given altitudes. The attenuation of photons towards the telescope has been calculated for Rayleigh and Mie scatterings. With the developed simulation, it was possible to study the dependence of the shower maximum depth in the atmosphere, considering dierent experimental congurations for the telescopes used in the Pierre Auger Observatory, Telescope Array and MonRAt. Finally, the reconstruction of the geometric parameters of cosmic rays has been performed by the determination of the arrival directions and the angular reconstruction limits.

Orientador: Jose Augusto Chinellato / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-11T05:35:22Z (GMT). No. of bitstreams: 1 Catalani_Fernando_D.pdf: 3151550 bytes, checksum: e2bbe39231b08bdb8fdcd358452d30f5 (MD5) Previous issue date: 2008 / Resumo: Essa tese tinha como objetivo estudar o perfil longitudinal de chuveiros atmosféricos extensos de forma completa. Nós simulamos chuveiros atmosféricos utilizando o programa CORSIKA para diferentes primários e energias acima de 10 17 e V e procuramos relações entre vários parâmetros extraídos do perfil longitudinal, como Xmax, X0, Xmax - X0, FWHM entre outros. Utilizamos os modelos de interação hadrônica QGSJET01 e SIBYLL2.1 nesses estudos. Um resultado obtido foi a contribuição de diferentes componentes de um chuveiro atmosférico no depósito de energia na atmosfera, para diferentes ângulos, primários e modelos de interação hadrônica. Calculamos, pela primeira vez, explicitamente as quantidades de energia calorimétrica e energia perdida que são necessárias para a recosntrução da energia do primário. Pudemos, então, parametrizar a fração de energia perdida em termos da energia calorimétrica e da energia do primário. Essa parametrização varia menos de 1 % com o ângulo zenital e com o nível de observação. Já a dependência com o primário é menor que 5 % e com o modelo de interação hadrônica é menor que 2 %.Calculamos como menor que 3 % o erro sistemático de corrigir a energia perdida usando uma parametrização mista de 50 % de chuveiros de ferro e 50 % chuveiros de próton. Aplicamos métodos estatísticos no estudo da composição de raios cósmicos. Como resultado, propomos a utilização de vários parâmetros do perfil longitudinal como Xmax, Nmax, Sigma, Assimetria, Skewness and Kurtose. Através do método de análise de componentes principais (PCA) nós estudamos a relevência de cada um desses parâmetros na caracterização do perfil longitudinal. Aplicamos, então, a análise de discriminantes lineares (LDA) para encontrar uma combinação linear dos parâmetros usados que melhor classifique um chuveiro como sendo originado por próton, ferro e fótons. Mostramos que LDA permite uma melhor separação entre chuveiros de hádrons e fótons e entre chuveiros de prótons e ferro que métodos baseados apenas na medida de Xmax / Abstract: The aim of this thesis was to study in a thoroughly way the longitudinal profile of air showers. We simulated air showers for different primaries and energies with the CORSIKA program and searched for relations between several parameters extracted from longitudinal profile, like Xsub>max, X0, Xmax-X0, FWHM and others. Hadronic interaction models QGSJET01 and SiBYLL2.1 were used in these studies. One result was the contribution for different components of an air shower to the energy deposit in the atmosphere, considering different angles, primary particles and hadronic interaction models was studied. We calculated, for the first time, the amounts of calorimetric energy and missing energy which are essential to reconstruct the primary energy. Thus, we could parameterize the fraction of missing energy in terms of the primary energy as a function of calorimetric energy. This parametrization varies less than 1% with angle and observation level. We showed that the dependence with primary mass is less than 5 % and with hadronic interaction model is below 2%. Using a parametrization with a mixture of 50 % of proton and 50 % iron showers at 45° to correct the missing energy the systematic error found was less than 3 %. Finally, we applied statistical methods in the composition studies of air showers. As a result, we propose the utilization of several features of air shower longitudinal profiles such as Xmax, Nmax, Sigma, Asymmetry, Skewness and Kurtosis. First we studied the relevance of each parameter for the overall shower features using principal component analysis (PCA). Then, we applied linear discriminant analysis (LDA) to find a linear combination of the shower parameters that best classifies a shower as an iron, proton or photon originated shower. We showed that LDA provides a better separation between iron and proton showers than using only Xmax-based methods / Doutorado / Física das Particulas Elementares e Campos / Doutor em Ciências

Orientador: Carlos Ourivio Escobar / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-11T18:57:31Z (GMT). No. of bitstreams: 1 Peixoto_CarlosJoseTodero_D.pdf: 15351567 bytes, checksum: 33b4f282f53a5669d23f8170b3bbf392 (MD5) Previous issue date: 2008 / Resumo: Desde os primeiros Raios Cósmicos de alta energia detectados por Pierre Auger na década de 30, toda a comunidade de Física de Radiação Cósmica procura técnicas matemáticas e métodos estatísticos mais adequados para analisar estes eventos. Estes processos de análise são imprescindíveis na estimativa da energia da partícula primária, bem como no cálculo do ângulo de chegada q . A estimativa desta energia e do ângulo q é o final de toda uma rede de trabalho e o começo de uma nova linha de pesquisa na busca pelas possíveis fontes que produziram tais eventos. Ao longo deste trabalho refizemos o princípio de reconstrução dos "chuveiros de Auger", os chamados "Chuveiros Atmosféricos Extensos" ( C.A.E.), utilizando um conceito relativamente novo de estatística, hoje denominada Estatística Robusta. O Método dos Mínimos Quadrados ou Least Square -LS, apresentado por Gauss e Legendre, possuía limitações que eles próprios já reconheciam e tentaram resolver, sem sucesso. Desde fins do século XVIII e come¸ co do século XIX, os métodos estritamente paramétricos, em especial o Método dos Mínimos Quadrados e a média aritmética, foram questionados quando utilizados para descrever distribuições pouco comportadas ou com grandes utuações. Algumas das principais questões estavam relacionadas a como tratar pontos muito distantes da distribuição principal (os chamados outliers) e como estes influenciavam a própria distribuição. A saída convencional mais utilizada foi a rejeição dos outliers e de pontos que apresentassem grandes desvios em relação a média. Porém, a perda de informações sobre a própria distribuição tornava-se inevitável. O modelo paramétrico mostrou-se apenas uma aproximação da realidade, uma vez que as flutuações, apesar de serem consideradas, não são "bem-vindas"; são vistas apenas como um erro inerente à observação. Então, no fim do século XIX apareceram as primeiras tentativas de extrair informação das flutuações, classificando-as e as considerando parte integral da descrição da distribuição. Se um método estatístico for capaz de descrever os dados observados, incluindo e classificando as flutuações inerentes, este passa a ser conhecido como "Método Robusto" ou "Estatística Robusta", onde a nomenclatura "Robusta" está relacionada à capacidade do método ou modelo de "resistir" às flutuações fornecendo uma descrição da realidade com razoável independência destas mesmas flutuações. Com base em dois métodos robustos, Mínima Mediana Quadrada (Least Median Square - LMS) e Mínimos Quadrados "Aparados" (Least Trimmed Square - LTS), aplicamos estes nos ajustes da Função Distribuição Lateral de Chuveiros (Lateral Distribution Function - LDF) extraindo o valor de S 1000, parâmetro necessário para estimar a energia da partícula primária. Os valores para S1000 calculados a partir de estatística convencional (Mínimos Quadrados) e estatística robusta (LMS e LTS) são comparados. O valor de S1000, para chuveiros de mesma energia, depende do ângulo q dos primários, já que o CAE sofre atenuação na atmosfera, atenuação esta tanto maior quanto maior, for q . Para levar em conta a atenuação no cálculo do espectro de energia, em que todos os ângulos de chegada são considerados (até 60 graus), é introduzido o parâmetro S38, onde 38 graus é a mediana dos dados do Auger. A atenuação é calculada usando-se o método do Constant Intensity Cut (CIC) o qual depende da validade de várias hipóteses. As três hipóteses supostas pela Colaboração Auger são apresentadas neste trabalho. Correlacionamos, assim, todos os novos valores de S38 com os valores da chamada "Energia Híbrida", obtida diretamente do programa de análise da Colaboração Auger. Esta correlação nos permite recorrigir a energia com base em detecção híbrida, que é a grande vantagem do Observatório Pierre Auger. Esta correlação nos permite estabelecer a escala de energia ou calibração do detector de superfície com base na determinação calorimétrica da energia feita pelo detector de flurescência, que é o grande avançoo trazido para o campo pelo Obvservatório Pierre Auger. Com os novos resultados de energia, refizemos os cálculos de minimização para a correlação de radiação cósmica com fontes extra-galácticas obtendo correlações que não estão em correspondência biunívoca com aquelas obtidas pelo método convencional de análise. Por fim fazemos uma análise das próprias estações outliers tentando extrair alguma informação relacionada à performance do detector de superfície. Os apêndices incluídos após as conclusões foram colocados neste trabalho apenas por motivos didáticos como consulta rápida para o leitor leigo em métodos de detecção de radiação cósmica / Abstract: Since the first ultra high-energy cosmic rays detected by Pierre Auger (the 30s) the entire community of Physics of Cosmic Rays search for mathematical techniques and more appropriate statistical methods to analyze these events. These analysis processes are essential for the estimate of the energy of the primary particle as well as in the calculation of the angle of arrival q . The estimate of the energy and the angle q is the end of a long chain of analysis and the beginning of a new line of research in the search for the possible sources that produced such events. Throughout this work we re-analysed the reconstruction chain of the "Auger showers", the socalled "Extensive Air Showers - EAS", using a relatively new concept of statistics, known as Robust Statistics. The Least Square Method - LS, presented by Gauss and Legendre had limitations already recognized by themselves who tried to overcome them without success. Since the end of the eighteenth century and beginning of the nineteenth century, strictly parametric methods, especially the Least Squares and the arithmetic average, were questioned when used to describe distributions with bad behavior or with large uctuations. Some of the main issues were related to how to deal with points far way from the main distribution (the so-called outliers) and how it in uenced the main distribution. The more conventional way out used was the rejection of the outliers and points that produced large deviations from average. But the loss of information about the distribution was inevitable. The parametric model proved to be only an approximation of reality, since uctuations, despite being considered, are not "welcome"; are seen only as an error inherent in observation. Then, at the end of the nineteenth century there appeared the first attempts to extract information from uctuations sorting them out and considering them as an integral part of the description of the distribution. Whether a statistical method is able to describe observed data, including and sorting the uctuations inherent, then becomes known as "Robust Method" or "Robust Statistic", where the nomenclature "Robust" is related the ability of the method or model to "Resist" the uctuations by providing a description of reality with reasonable independence these same uctuations. Based on two robust methods: Least Median Square - LMS and Least Trimmed Square - LTS; we apply these to adjust the Lateral Distribution Function - LDF extracting the value of S1000, parameter needed to estimate the energy of the primary particle. The values for S1000 calculated from conventional statistic (Least Square) and robust statistic (LMS and LTS) are compared. The parameter S1000 is dependent on the angle of arrival of the shower, then we apply a correction factor called S38. This correlates S1000 and and, currently, there are several ways to calculate this factor. The three hypotheses most used by Auger Collaboration are presented in this work. We then correlate all new values of S38 with the values of the so-called "Hybrid Energy", obtained directly from analysis software of the Auger Collaboration. This relationship allows us to correct the energy based on hybrid detection that is great advantage of the Pierre Auger Observatory. This relationship allows us to establish the energy scale or calibration of the surface detector on the basis of the calorimetric determination of the energy done by the uorescence detector which is the great advancement brought to the field by the Pierre Auger Observatory. With the new results for the energy we reanalysed the the correlation with extra-galactic sources of cosmic ray getting new correlations, which are absent in the conventional methods of analysis. Finally we make an analysis of the surface stations outliers by themselves trying to extract some information relevant for their performance. Appendices included after the conclusions were placed in this work only for a rapid consultation by lay readers in methods of detection of cosmic rays / Doutorado / Teorias Especificas e Modelos de Interação ; Sistematica de Particulas ; Raios Cosmicos / Doutor em Ciências