• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 4
  • 3
  • Tagged with
  • 17
  • 17
  • 17
  • 17
  • 17
  • 8
  • 8
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Étude du fonctionnement d'un télescope de lumière de fluorescence dans le cadre du projet EUSO-Balloon / Study of a fluorescence telescope for the EUSO-Balloon project

Moretto, Camille 02 October 2015 (has links)
L'instrument EUSO-Balloon est un prototype pour le télescope JEM-EUSO, destiné à observer pour la première fois depuis l’espace les gerbes atmosphériques induites par les rayons cosmiques d'ultra-haute énergie. Le principe de détection repose sur la mesure des photons émis par la fluorescence de l’atmosphère terrestre lors du développement des gerbes. EUSO-Balloon, un télescope UV embarqué à bord d’un ballon stratosphérique, a pour but de prouver la pertinence des concepts instrumentaux développés dans le cadre du projet JEM-EUSO. Cette thèse est dédiée en grande partie à l’assemblage, l’intégration et les tests du module de photo-détection d’EUSO-Balloon. Il s’agit d’un ensemble de 36 tubes photomultiplicateurs multi-anodes, pour un total de 2304 pixels, et d’une électronique de lecture permettant d’imager le développement, s’effectuant à la vitesse de la lumière, des gerbes atmosphériques. Cette caméra permet ainsi de réaliser des images de 2,5 microsecondes avec une sensibilité au photo-électron unique. Il aura été démontré que la mesure de l’efficacité de photo-détection de la caméra est réalisable avec une précision inférieure à 5% pour la tension de polarisation adaptée. EUSO-Balloon a effectué son premier vol en août 2014 lors duquel il a été prouvé, grâce à l’utilisation d’événements simulés par tirs lasers, qu’il est possible d’imager le développement de gerbes atmosphériques depuis le proche espace. Les données enregistrées permettent de réaliser une étude sur le bruit de fond UV produit par l’atmosphère terrestre. L’ensemble du travail d’assemblage, d’intégration et de test permet d’envisager les développements pour les futures missions. / The EUSO-Balloon instrument is a prototype for the JEM-EUSO telescope, intended to observe for the first time from space the extensive air showers (EAS) induced by the ultra-high energy cosmic rays. The detection technique relies on the measurement of the photons produced by the fluorescence of the Earth’s atmosphere when EAS develop. EUSO-Balloon, a UV telescope payload of a stratospheric balloon, has the objective to prove the relevance of the concepts developed for the JEM-EUSO project. An important part of this thesis is devoted to the assembly, the integration and the test of the EUSO-Balloon’s photo-detection module. It is an array of 36 multi-anodes photo-multiplier tubes, for a total of 2,304 pixels, and of a readout electronics able to image the development at the speed of the light of the EAS. It has a framing time of 2.5 microseconds with a single photo-electron sensitivity. It has been proved that the photo-detection efficiency of this camera can be measured with an accuracy better than 5% for the proper polarization voltage. The first flight of EUSO-Balloon happened in August 2014 and proved, with the use of laser induced events, that air showers can be imaged for the near space. Data acquired during this flight allow to study the UV background originating from the Earth’s atmosphere. The assembly, integration and test work provided during this project leads the development of future missions.
12

Experimental studies of the muonic component of extensive air showers / Estudos experimentais da componente muônica de chuveiros atmosféricos extensos

Prado, Raul Ribeiro 20 April 2018 (has links)
Ultra-High Energy Cosmic Rays (UHECR) can only be measured by the detection of Extensive Air Showers (EAS) created by the interaction of the cosmic ray particle with an atmospheric nuclei. The inference of some of the properties of UHECR, like their mass composition, is only possible by the comparison of measurements of EAS observables to predictions from Monte Carlo simulations. The most important source of uncertainties on the description of EAS by the simulations is the modeling of hadronic interactions. For many years it has been known that the hadronic interaction models fail on predicting the EAS observables related to their muonic component. The most evident manifestation of that is called muon deficit problem due to the fact that the number of muons in EAS with energies above 1018 eV predicted by simulations is smaller than the observed ones. The aim of this thesis is to approach this problem in three distinct fronts. First, a method is developed to interpret measurements of number of muons in terms of cosmic rays composition in despite of the muon deficit problem. Second, an EAS observable which is sensitive to the muon energy spectrum at ground and, consequently, can be used to constrain hadronic interaction models is proposed and tested. Third and final, the muon production in air showers is studied through measurements of hadron production spectra in pion-carbon interactions. / Raios Cósmicos Ultra Energéticos (Ultra-High Energy Cosmic Rays, UHECR) somente podem ser medidos através da detecção dos Chuveiros Atmosféricos Extensos (Extensive Air Showers, EAS) criados pela interação do raio cósmico primário com núcleos atmoféricos. A inferência de algumas propriedados dos UHECRs, como a composição de massa, é possível somente através da comparação entre medidas de observáveis dos EASs com predições geradas por simulações de Monte Carlo. A fonte de incerteza mais importante na descrição de EAS por simulações é a modelagem das interações hadrônicas. Por muitos anos é sabido que os modelos de interação hadrônica falham na predição de observáveis dos EASs relacionados a sua componente muônica. A manifestação mais evidente disso é chamada problema do déficit de múons devido ao fato que o número de múons em chuveiros com energias acima de 1018 eV predito por simulações é menor que os observados. O objetivo desta tese é abordar este problema através de três frentes. Primeiramente, um método é desenvolvido para interpretar as medidas do número de múons em termos de composição de raios cósmicos considerando o problema do déficit de múons. Segundo, a proposta e o teste de um observável que é sensível ao espectro de energia dos múons na superfície e, consequentemente, pode ser usado para discriminar entre os modelos de interação hadrônica. Por último, a produção de múons em chuveiros é estudada através de medidas do espectro de produção de hádrons em interações do tipo píon-carbono.
13

Effects of Lorentz invariance violation on the ultra-high energy cosmic rays spectrum / Efeitos da violação da invariância de Lorentz no espectro de raios cósmicos de altíssima energia

Lang, Rodrigo Guedes 13 February 2017 (has links)
Relativity is one of the most important and well tested theories and Lorentz invariance is one of its pillars. Lorentz invariance violation (LIV), however, has been discussed in several quantum gravity and high energy models. For this reason, it is crucial to test it. Several tests, both terrestrial and astrophysical, have been performed in the last years and provide limits on the violation. This work takes part in these efforts and discuss the possibility of testing LIV with ultra-high energy cosmic rays (UHECRs). The effects of LIV in their propagation and the resulting changes in the spectrum of UHECRs are obtained and compared to the experimental data from the Pierre Auger Observatory. An analytical calculation for the inelasticity in the laboratory frame with LIV of any a + b → c + d interaction is presented and used to obtain the phase space and the energy losses of the pion production for protons, the photodisintegration for nuclei and the pair production for photons with LIV. A parametrization for the threshold energy of the photodisintegration with LIV is also proposed. The main effect seen is a decrease in the phase space and a resulting decrease in the energy loss. These changes have been implemented in Monte Carlo propagation codes and the resulting spectra of protons, nuclei and photons on Earth have been obtained and fitted to the data from the Pierre Auger Observatory. It is shown that upper limits on the photon LIV coefficient can be derived from the upper limits on the photon flux from the Pierre Auger Observatory. / Relatividade é uma das mais importantes e bem testadas teorias e a invariância de Lorentz é um de seus pilares. A violação da invariância de Lorentz (VIL), todavia, tem sido discutida em diversos modelos de gravidade quântica e altas energias. Por tal motivo, é crucial testá-la. Diversos testes, tanto terrestres quanto astrofísicos, foram realizados nos últimos anos e fornecem limites na violação. Este trabalho se insere nesses esforços e discute a possibilidade de testar VIL com raios cósmicos de altíssima energia. Os efeitos da VIL em sua propagação e as consequentes mudanças no espectro de raios cósmicos de altíssima energia são obtidos e comparados com os dados experimentais do Observatório Pierre Auger. Um cálculo analítico para a inelasticidade no referencial do laboratório com VIL para qualquer interação da forma a + b → c + d é apresentado e usado para obter o espaço de fase e as perdas de energia para a produção de píons para prótons, a fotodesintegração para núcleos e a produção de pares para fótons com VIL. Uma parametrização para o limiar de energia da fotodesintegração com VIL também é proposta. O principal efeito observado é uma diminuição no espaço de fase e uma consequente diminuição nas perdas de energia. Tais mudanças foram implementadas em códigos de Monte Carlo para a propagação e os espectros resultantes para prótons, núcleos e fótons na Terra foram obtidos e ajustados aos dados do Observatório Pierre Auger. É mostrado que limites superiores nos coeficientes de VIL para o fóton podem ser deduzidos dos limites superiores para o fluxo de fótons do Observatório Pierre Auger.
14

Effects of Lorentz invariance violation on the ultra-high energy cosmic rays spectrum / Efeitos da violação da invariância de Lorentz no espectro de raios cósmicos de altíssima energia

Rodrigo Guedes Lang 13 February 2017 (has links)
Relativity is one of the most important and well tested theories and Lorentz invariance is one of its pillars. Lorentz invariance violation (LIV), however, has been discussed in several quantum gravity and high energy models. For this reason, it is crucial to test it. Several tests, both terrestrial and astrophysical, have been performed in the last years and provide limits on the violation. This work takes part in these efforts and discuss the possibility of testing LIV with ultra-high energy cosmic rays (UHECRs). The effects of LIV in their propagation and the resulting changes in the spectrum of UHECRs are obtained and compared to the experimental data from the Pierre Auger Observatory. An analytical calculation for the inelasticity in the laboratory frame with LIV of any a + b → c + d interaction is presented and used to obtain the phase space and the energy losses of the pion production for protons, the photodisintegration for nuclei and the pair production for photons with LIV. A parametrization for the threshold energy of the photodisintegration with LIV is also proposed. The main effect seen is a decrease in the phase space and a resulting decrease in the energy loss. These changes have been implemented in Monte Carlo propagation codes and the resulting spectra of protons, nuclei and photons on Earth have been obtained and fitted to the data from the Pierre Auger Observatory. It is shown that upper limits on the photon LIV coefficient can be derived from the upper limits on the photon flux from the Pierre Auger Observatory. / Relatividade é uma das mais importantes e bem testadas teorias e a invariância de Lorentz é um de seus pilares. A violação da invariância de Lorentz (VIL), todavia, tem sido discutida em diversos modelos de gravidade quântica e altas energias. Por tal motivo, é crucial testá-la. Diversos testes, tanto terrestres quanto astrofísicos, foram realizados nos últimos anos e fornecem limites na violação. Este trabalho se insere nesses esforços e discute a possibilidade de testar VIL com raios cósmicos de altíssima energia. Os efeitos da VIL em sua propagação e as consequentes mudanças no espectro de raios cósmicos de altíssima energia são obtidos e comparados com os dados experimentais do Observatório Pierre Auger. Um cálculo analítico para a inelasticidade no referencial do laboratório com VIL para qualquer interação da forma a + b → c + d é apresentado e usado para obter o espaço de fase e as perdas de energia para a produção de píons para prótons, a fotodesintegração para núcleos e a produção de pares para fótons com VIL. Uma parametrização para o limiar de energia da fotodesintegração com VIL também é proposta. O principal efeito observado é uma diminuição no espaço de fase e uma consequente diminuição nas perdas de energia. Tais mudanças foram implementadas em códigos de Monte Carlo para a propagação e os espectros resultantes para prótons, núcleos e fótons na Terra foram obtidos e ajustados aos dados do Observatório Pierre Auger. É mostrado que limites superiores nos coeficientes de VIL para o fóton podem ser deduzidos dos limites superiores para o fluxo de fótons do Observatório Pierre Auger.
15

Experimental studies of the muonic component of extensive air showers / Estudos experimentais da componente muônica de chuveiros atmosféricos extensos

Raul Ribeiro Prado 20 April 2018 (has links)
Ultra-High Energy Cosmic Rays (UHECR) can only be measured by the detection of Extensive Air Showers (EAS) created by the interaction of the cosmic ray particle with an atmospheric nuclei. The inference of some of the properties of UHECR, like their mass composition, is only possible by the comparison of measurements of EAS observables to predictions from Monte Carlo simulations. The most important source of uncertainties on the description of EAS by the simulations is the modeling of hadronic interactions. For many years it has been known that the hadronic interaction models fail on predicting the EAS observables related to their muonic component. The most evident manifestation of that is called muon deficit problem due to the fact that the number of muons in EAS with energies above 1018 eV predicted by simulations is smaller than the observed ones. The aim of this thesis is to approach this problem in three distinct fronts. First, a method is developed to interpret measurements of number of muons in terms of cosmic rays composition in despite of the muon deficit problem. Second, an EAS observable which is sensitive to the muon energy spectrum at ground and, consequently, can be used to constrain hadronic interaction models is proposed and tested. Third and final, the muon production in air showers is studied through measurements of hadron production spectra in pion-carbon interactions. / Raios Cósmicos Ultra Energéticos (Ultra-High Energy Cosmic Rays, UHECR) somente podem ser medidos através da detecção dos Chuveiros Atmosféricos Extensos (Extensive Air Showers, EAS) criados pela interação do raio cósmico primário com núcleos atmoféricos. A inferência de algumas propriedados dos UHECRs, como a composição de massa, é possível somente através da comparação entre medidas de observáveis dos EASs com predições geradas por simulações de Monte Carlo. A fonte de incerteza mais importante na descrição de EAS por simulações é a modelagem das interações hadrônicas. Por muitos anos é sabido que os modelos de interação hadrônica falham na predição de observáveis dos EASs relacionados a sua componente muônica. A manifestação mais evidente disso é chamada problema do déficit de múons devido ao fato que o número de múons em chuveiros com energias acima de 1018 eV predito por simulações é menor que os observados. O objetivo desta tese é abordar este problema através de três frentes. Primeiramente, um método é desenvolvido para interpretar as medidas do número de múons em termos de composição de raios cósmicos considerando o problema do déficit de múons. Segundo, a proposta e o teste de um observável que é sensível ao espectro de energia dos múons na superfície e, consequentemente, pode ser usado para discriminar entre os modelos de interação hadrônica. Por último, a produção de múons em chuveiros é estudada através de medidas do espectro de produção de hádrons em interações do tipo píon-carbono.
16

Ultra-high-energy cosmic-ray nuclei and neutrinos in models of gamma-ray bursts and extragalactic propagation

Heinze, Jonas 08 June 2020 (has links)
Utrahochenergetische kosmische Strahlung (ultra-high-energy cosmic rays -- UHECR) besteht aus ionisierten Atomkernen mit den höchsten Teilchenergien, die je gemessen wurden. Zwar wurden die Quellen von UHECRs noch nicht eindeutig identifiziert, doch gibt es deutliche Anzeichen, dass sie extragalaktisch sind. Um die Beobachtungen zu interpretieren, wird ein Modell der Wechselwirkungen mit Photofeldern sowohl in der Quelle als auch während der extragalaktischen Propagation benötigt. Bei diesen Wechselwirkungen werden sekundäre Neutrinos erzeugt. Diese Dissertation behandelt Modelle der Quellen von UHECRs und die damit verbundene Produktion von Neutrinos sowohl in den Quellen als auch während der Propagation. Dafür wurde ein neuer Code, PriNCe, für die Propagation von UHECRs entwickelt. Dieser Code wird in einem umfangreichen Parameterscan für ein generisches Quellenmodell angewendet, welches mit dem Spektralindex, der maximalen Rigidität, der kosmologischen Quellenverteilung und der chemischen Komposition als freie Parameter definiert ist. Dabei wird der Einfluss von verschiedenen Photodisintegrations- und Luftschauermodellen auf die erwarteten Eigenschaften der Quellen demonstriert. Der Fluss kosmogenischer Neutrinos, der sich daraus robust vorhersagen lässt, liegt außerhalb der Reichweite aller derzeit geplanten Neutrinodetektoren. GRBs als mögliche Quellen von UHECRs werden im Multi-Collision Internal-Shock Modell simuliert, welches die Abhängigkeit der Strahlungsprozesse von den verschiedenen Dissipationsradien im Plasmajet berücksichtigt. Für dieses Modell wird der Effekt demonstriert, den verschiedene Annahmen über die anfängliche Verteilung des Plasmajets und das hydrodynamische Modell auf die resultierende UHECR- und Neutrinosstrahlung haben. Für den Gammastrahlenblitz GRB170817A, welcher zusammen mit einem Gravitationswellensignal beobachtet wurde, werden Vorhersagen für den Neutrinofluss und ihre Abhängigkeit vom Beobachtungswinkel gemacht. / Ultra-high-energy cosmic rays (UHECRs) are the most energetic particles observed in the Universe. While the astrophysical sources of UHECRs have not yet been uniquely identified, there are strong indications for an extragalactic origin. The interpretation of the observations requires both simulations of UHECR acceleration and energy losses inside the source environment as well as interactions during extragalactic propagation. Due to their extreme energies, UHECR will interact with photons in these environments, producing a flux of secondary neutrinos. This dissertation deals with models of UHECR sources and the accompanying neutrino production in the source environment and during extragalactic propagation. We have developed a new, computationally efficient code, PriNCe, for the extragalactic propagation of UHECR nuclei. The PriNCe code is applied for an extensive parameter scan of a generic source model that is described by the spectral index, the maximal rigidity, the cosmological source evolution and the injected mass composition. In this scan, we demonstrate the impact of different disintegration and air-shower models on the inferred source properties. A prediction for the expected flux of cosmogenic neutrinos is also derived. GRBs are discussed as specific UHECR source candidates in the multi-collision internal-shock model. This model takes the radiation from different radii in the GRB outflow into account. We demonstrate how different assumptions about the initial setup of the jet and the hydrodynamic collision model impact the production of UHECRs and neutrinos. Motivated by the multi-messenger observation of GRB170817A, we discuss the expected neutrino production from this GRB and its dependence on the observation angle. We show that the neutrino flux for this event is at least four orders of magnitude below the detection limit for different geometries of the plasma jet.
17

New Interaction Models of Ultra-high-energy Cosmic Rays from a Nuclear Physics Approach

Morejon, Leonel 25 March 2021 (has links)
Der Ursprung der ultrahochenergetischen kosmischen Strahlung (UHECRs) benötigt Modelle der photonuklearen kosmischen Strahlungsinteraktionen. In dieser Arbeit stelle ich Modelle vor, die drei Aspekte der Modellierung der Hochenergie-Astronuklearphysik verbessern: die Photomesonenproduktion durch Kerne der kosmischen Strahlung, die schwerer als Protonen sind, die Gammastrahlenemission von instabilen Kernen, die durch den Photodisintegrationsprozess der kosmischen Strahlung erzeugt werden, und die Simulation der extragalaktischen Ausbreitung von Kernen, die schwerer als Eisen sind (sogenannte superschwere Isotope). Das Photomesonenmodell ist das erste in der Literatur, das über das einfache Prinzip der Nukleonen-Superposition hinausgeht. Es liefert eine detailliertere Beschreibung der inelastischen Wirkungsquerschnitte und des emittierten Spektrums von Sekundärteilchen, einschließlich Isotopen und Pionen, die zu Photonen und Neutrinos führen. Die Auswirkungen des Modells werden in Simulationen von Gammastrahlenausbrüchen und Gezeitenstörungsereignissen gezeigt, und es beeinflusst signifikant die hochenergetische Neutrinoemission, die chemische Zusammensetzung und das Spektrum der emittierten UHECRs. Das zweite Modell beschreibt die Photoproduktion aus den De-Exzitationen und Zerfällen instabiler Kerne, die aus dem Photozerfall der kosmischen Strahlung in Wechselwirkung mit astrophysikalischen Photonen resultieren sollen. Ihre Wirkung wird am Photoemissionsspektrum des Kerns von Centaurus A veranschaulicht und mit ähnlichen Arbeiten verglichen, mit denen es Unstimmigkeiten gibt. Schließlich wird der Photodesintegration von UHECR überschweren Kernen diskutiert. Eine Wechselwirkungstabelle wird unter Verwendung von Querschnitten aus TALYS konstruiert, und die Wechselwirkungsraten werden im Zusammenhang mit der extragalaktischen Ausbreitung berechnet. Überschwere Kerne breiten sich in bestimmten Energiebereichen weiter aus als leichtere Kerne. / The origin of the ultra-high-energy cosmic rays (UHECRs) is still unknown. Photonuclear interactions of cosmic rays are key to understanding this problem in a multimessenger context. Nuclear physics insights are crucial in building accurate models to interpret the data that indicates UHECR can be heavier than protons. This thesis presents models that improve three aspects of high-energy astronuclear physics modelling: photomeson production by cosmic-ray nuclei heavier than protons, gamma-ray emission from unstable nuclei created by the photodisintegration of cosmic rays, and the simulation of extragalactic propagation of nuclei heavier than iron (so-called superheavy isotopes). The photomeson model is the first in the literature to go beyond the simple principle of nucleon superposition. It provides a more accurate description of the inelastic cross sections, and the emitted spectrum of secondary particles, including isotopes and pions which lead to photons and neutrinos.The model’s impact is shown in simulations of gamma-ray bursts and tidal disruption events, and it affects significantly the high-energy neutrino emission, the chemical composition and the spectrum of the emitted UHECRs. The second model describes photoproduction from de-excitations and decay of unstable nuclei, which are expected to be produced in photo-disintegration of cosmic rays interacting with astrophysical photons. Its impact is illustrated in the photo-emission from the core of the Centaurus A and compared to similar works with which is in disagreement. This supports the need for sufficiently accurate models. Lastly, the photodisintegration of UHECR superheavy nuclei is discussed. An interaction table is produced with cross sections obtained from TALYS and the interaction rates computed in the context of extragalactic propagation. Superheavy nuclei propagate further than lighter nuclei in certain energy ranges. The models developed are publicly available as open-source software.

Page generated in 0.083 seconds