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  • 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.
331

Études théoriques et expérimentales des effets singuliers induits par les muons atmosphériques sur les technologies numériques d’échelle nanométrique / Theoretical and experimental studies of the Single Event Effect induced by atmospheric muons on numerical technologies of nanometric scales

Li Cavoli, Pierre 13 December 2016 (has links)
Cette étude s’inscrit dans le domaine de la microélectronique. Elle consiste à étudier l’impact de la morphologie 3D du dépôt d’énergie sur la modélisation des événements singuliers (SEE) induits par les muons atmosphériques. La démarche a consisté dans un premier temps à modéliser le dépôt d’énergie induits par des protons dans des volumes nanométriques. Pour cela, le code Monte-Carlo GEANT4 a permis de simuler et de stocker dans une base de données, les caractéristiques des traces des dépôts d’énergie des protons. Une fois la démarche validée pour les protons, des simulations du dépôt d’énergie induit par des muons ont été réalisées. Une caméra CCD a été utilisée afin de réaliser des mesures de l’environnement radiatif atmosphérique et de contraindre la modélisation des dépôts d’énergie induits par les muons. Cette étude met en évidence et quantifie l’apport de considérer la distribution radiale du dépôt d’énergie induit par des protons pour des volumes nanométriques, dans les calculs de prédiction des SEE. En revanche, l’étude montre que la considération de la distribution radiale du dépôt d’énergie induit par des muons dans des volumes nanométriques a un impact négligeable sur la modélisation des SEE. Il serait intéressant de réaliser des mesures du dépôt d’énergie induit par des muons dans des technologies nanométriques sous accélérateur. Cela permettrait d’apporter des données expérimentales encore inexistantes, nécessaires au développement de nouveaux modèles physiques plus précis sur la modélisationdu dépôt d’énergie induit par des muons. / This study concerns the domain of the microelectronics. It consists in the studyof the impact of the 3D morphology of the energy deposit on the Single EventEffect (SEE) modeling, induced by atmospheric muons. Over a first phase, theapproach has consisted in the modeling of the energy deposit induced by protonsin nanometric volumes. For that purpose the use of the Monte Carlo code GEANT4has allowed to simulate and stock in a database the tracks characteristics of theenergy deposit induced by protons. Once the approach validated for the protons,simulations of the energy deposit induced by muons have been realized. A CCDcamera has been used in order to measure the radiative atmospheric environmentand to constrain the modeling of the energy deposit induced by muons. This studyhighlights and quantify the contribution of the radial distribution of the energydeposit incuced by protons in nanometric volumes for the SEE prediction. On theother hand, the study shows that the contribution of the radial distribution of theenergy deposit induced by muons in nanometric volumes has a negligeable impacton the SEE modeling. It will be interesting to realize measurements of the energydeposit induced by muons in nanometric technologies under accelerator. This willallow to bring experimental data still nonexistant necessary to the developpmentof new physical models more accurate on the modelization of the energy depositinduced by muons.
332

The SALT HRS Spectrograph

Tyas, Luke Martin Graham January 2012 (has links)
SALT HRS (Southern African Large Telescope High Resolution Échelle Spectrograph) is a high-resolution, high-efficiency spectrograph for the 11m SALT telescope in Sutherland, South Africa. The initial optical design work was performed at the University of Canterbury, New Zealand. Revisions to the concept, the mechanical design, manufacture, assembly and testing have been handled by the Centre for Advanced Instrumentation, at Durham University in the United Kingdom. SALT HRS is a fibre-fed echelle grating spectrograph with four operational modes: low-, medium- and high-resolution and high-stability modes, having spectral resolutions of R ≈16000, 37000, 67000 and 67000 respectively over a wavelength range of 370-890nm. The instrument is of a dual channel, ‘white pupil’ design, in which the primary mirror acts to collimate light onto a single R4 echelle grating, and also to focus dispersed light to an intermediate focus. A dichroic beam-splitter separates the dispersed light into two separate spectral channels. Spherical pupil mirrors transfer the separated beams via a fold mirror to two wavelength-specific volume-phase holographic gratings (VPHGs) used as cross-dispersers. Cross-dispersed spectra are then imaged by two fully dioptric camera systems onto optimized CCD detectors. This thesis presents the results of the laboratory testing and specification of several critical sub-systems of SALT HRS, as well as the development of key software tools for the design verification and operation at the telescope. In Chapter 1 we first review the technical development of high-resolution spectroscopy and its specific implementation in SALT HRS. In Chapter 2 we develop a comprehensive throughput model of the entire system based on a combination of as-built performance and specific throughput measurements in the laboratory. This is used to make some specific predictions for the on-sky performance of SALT HRS and the magnitude limits for science targets. We also present a graphical exposure time calculator based on these measurements which can be used by an astronomer to plan their observations with SALT HRS. Chapter 3 contains a detailed treatise on the optical fibre system of SALT HRS. Considerations for the use of optical fibres in astronomy are provided, as are details of an optional double scrambler, and the various instrument fibre modes. Extensive measurements of focal ratio degradation (FRD) are also presented, with testing of input beam speed; wavelength; fibre bending; variable pupil mirror illumination; and vacuum tank pressure dependency. The systems for fibre management are reviewed, as is the fibre bundle assembly process. Testing of two further sub-systems is described in Chapter 4. Firstly the long-term stability of the mirror mounting mechanisms is determined. The advantages of cross-dispersion of echelle spectra using volume-phase holographic gratings are then discussed, and the results of diffraction efficiency measurements are given for both red and blue channel gratings. Modern CCD technologies are examined in Chapter 5, and the blue detector is experimentally characterized using photon transfer and quantum efficiency curves. It is also used for an investigation into cosmic ray events in CCDs. Results from shielding the detector using lead are described, as is an attempt to distinguish the source of the events based on their morphology. Finally, Chapter 6 deals with the handling of data produced by SALT HRS. Methods of wavelength calibration of the spectra are discussed, including the use of Thorium-Argon lamps and an iodine absorption cell. The implementation of a Python based quick-look data reduction pipeline is reviewed, with a description of the processes performed. A summary of the thesis is given in Chapter 7.
333

Different approaches to determine the composition of the ultra-high energy cosmic rays in the Pierre Auger Observatory / Différentes approches de la détermination de la masse des rayons cosmiques d'ultra haute énergie faite à l'Observatoire Pierre Auger

Blanco Otano, Miguel 12 December 2014 (has links)
L’objectif de cette thèse est d’améliorer la détermination de la masse des rayons cosmiques d’ultra haute énergie faite à l’Observatoire Pierre Auger. Aujourd’hui cette mesure est faite à travers l’utilisation de télescopes à fluorescence qui nécessitent des conditions de luminosité spéciales réduisantle cycle utile à environ 10%. Trois approches différentes sont proposées:La première approche est une nouvelle analyse. Les muons issus des gerbes horizontales sont déviés par le champ magnétique terrestre. Cette déviation modifie l’empreinte au sol des gerbes atmosphériques et est fonction de la longueur de parcours des muons. Un estimateur de Xμmax, leur point de productionmaximum, qui dépend de la masse du primaire peut être construit.La deuxième approche explore la détection du rayonnement radio émis par les gerbes atmosphériques, une technique similaire à la fluorescence mais sans limitation du cycle utile. La détection du rayonnement de Bremsstrahlung moléculaire est revue et explorée de différentes manières.La troisième approche propose un nouveau type de détecteur pour le réseau de surface, ces détecteurs ayant une réponse distincte aux différentes composantes des gerbes atmosphériques : électromagnétique et muonique. La mesure de la composante muonique est aussi un moyen d’accéder à la nature du primaire.La nouvelle analyse semble un outil prometteur qui peut s’appliquer à tout lot de données. La radio-détection en revanche n’apparaît pas comme une alternative compétitive face aux techniques traditionnelles. Le nouveau détecteur offre de belles perspectives et devrait être considéré pour l'équipementdes futurs observatoires. / The motivation of this PhD thesis is to improve the capabilities to determine the mass composition of the ultra-high energy cosmic rays in the Pierre Auger Observatory. The measure of their mass composition is done with the fluorescence technique, that needs special luminosity conditions that reduce the exposure time to about 10% of the time. Three different approaches are proposed.The first approach is a new analysis. Muons in the horizontal showers are deviated by the magnetic field of the Earth. This deflection is related with different characteristics of the extensive air shower that allow the construction of an estimator to obtain an alternative measure of Xμmax, an observable sensitive to the mass of the primary.The second approach is to explore the detection of the radio emission produced in the extensive air showers, a technique similar to the fluorescente one, but without the limitations in the duty cycle. The detection of the Molecular Bremsstrahlung Radiation emission is revised and investigated from different points of view.The third approach is to propose a new surface detector that obtains different responses to the different components of the extensive air shower: electromagnetic and muonic. The access to the muonic component is another way to access to the composition of the primary particle.The new method of analysis proposed appears as a promising tool to be applied in any data set. The technique of the radio detection did not show clear indications of being an alternative to traditional techniques. The new detector represents a promising alternative to be considered in any future ultra-high energy cosmic rays experiment.
334

Propagação e convolução do fluxo primário de raios cósmicos ultra-energéticos segundo a resolução de energia estimada do Observatório Pierre Auger / Propagation and convolution of the ultra-high energy cosmic ray spectrum due to the estimated energy resolution of the Pierre Auger Observatory

Rodrigues, João Paulo Caminha Cascudo 26 February 2007 (has links)
Orientador: Carola Dobrigkeit Chinellato / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-08T01:00:42Z (GMT). No. of bitstreams: 1 Rodrigues_JoaoPauloCaminhaCascudo_M.pdf: 7322384 bytes, checksum: e50136f5ec9d16fff8fd6a15ba64b5f0 (MD5) Previous issue date: 2007 / Resumo: Neste trabalho estuda-se a propagação pelo meio intergaláctico de raios cósmicos ultra-energéticos partindo de fontes com distribuição espacial uniforme, considerando as perdas de energia ocasionadas pela expansão adiabática do universo e pelas interações com a Radiação , Cósmica de Fundo (produção de pares e-e+ e fotoprodução de píons), o que resulta no aparecimento do corte GZK (Greisen-Zatsepin-Kuzmin). A degradação de energia no espectro primário da radiação cósmica que chega ao topo da atmosfera terrestre é então analisada para diferentes redshifts das fontes injetoras. São utilizadas simulações de Monte Carlo bem como uma abordagem analítica, com a posterior comparação dos resultados obtidos em cada método. Uma vez conhecido o fluxo propagado, é feita uma estimativa da forma da resolução de energia do Observatório Pierre Auger, com a decorrente convolução desta resolução com o fluxo propagado, novamente utilizando-se ambos os métodos. Os resultados mostram que o corte GZK pode se mostrar severamente atenuado no fluxo convoluído, o que dificulta a sua constatação experimental / Abstract: In this work, we study the propagation of Ultra-High Energy Cosmic Rays (UHECR) which are injected into the intergalactic medium by sources with flat spatial distribution for several redshifts. The energy spectrum of UHECR observed on the Earth is directly influenced by the energy losses due to both the adiabatic expansion of the universe and interactions with the Cosmic Microwave Background radiation (e-e+ pair production and photoproduction of pions), which cause the so-called Greisen-Zatsepin-Kuzmin (GZK) cutoff. We perform Monte Carlo simulations and also consider a semi-analytical approach and compare the results obtained by each method. Once the propagated primary flux is known, we make a simple estimate of the shape of the Pierre Auger Observatory energy resolution. This resolution is folded with the propagated primary flux again utilizing both methods. The results show the GZK cutoff may be severely smeared and might not be detected as sharp as predicted. / Mestrado / Teorias Especificas e Modelos de Interação ; Sistematica de Particulas ; Raios Cosmicos / Mestre em Física
335

Comparação entre produção de múons nos chuveiros atmosféricos extensos observados no Observatório Pierre Auger e nos detetores do experimento CMS do CERN, a partir de colisões próton-próton / Comparison between muon production in extensive air showers observed at Pierre Auger Observatory and at the detectors of CMS experiment at CERN, from proton-proton colisions

Moreno, Thiago Victor, 1988- 24 August 2018 (has links)
Orientador: José Augusto Chinellato / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-24T07:17:25Z (GMT). No. of bitstreams: 1 Moreno_ThiagoVictor_M.pdf: 9704369 bytes, checksum: 4998048904230625e6cb929460a8f975 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho o programa CORSIKA foi utilizado para gerar eventos de colisão próton-próton e chuveiros atmosféricos extensos com partícula primária sendo próton ou ferro. Como modelo de interações hadrônicas usou-se o EPOS LHC, QGSJET 01c, QGSJET II-4 e SIBYLL 2,1. As colisões p-p foram simuladas com energia igual a 7 TeV no referencial centro de momenta e foi estudada a distribuição de multiplicidade de hádrons carregados e a densidade em pseudorapidez. Comparando estes observáveis com dados do CMS escolheu-se os modelos que melhor reproduzissem os dados para posteriormente, simular chuveiros atmosféricos extensos. Estes chuveiros foram gerados com partícula primária de energia igual a 1019eV no referencial do laboratório. Observou-se a densidade de múons na altitude do Detetor de Superfície do Observatório de raios cósmicos Pierre Auger. O objetivo é estudar a possibilidade de usar esta densidade para sondar modelos de interações hadrônicas e identificar a partícula primária dos eventos detetados pelo Observatório Pierre Auger / Abstract: In this work CORSIKA program was used to generate events from proton-proton collision and extensive air showers with primary particle being proton or iron. The hadronic interaction models used was EPOS LHC, QGSJET 01c, QGSJET II-4 and SIBYLL 2,1. The p-p collisions were simulated with energy equal to 7 TeV in the center of momenta reference system and the charged hadron multiplicity and the pseudorapidity density was studied. Comparing this with data collected by the CMS detector at the LHC it was chosen the best models to generate air showers. The extensive air showers were generated with primary particle energy equal to 1019 eV in the laboratory frame. It was observed the muon density in the altitude of the Surface Detector of the Pierre Auger Observatory. The objective is to study the possibility of using this density to probe the model and the primary particle of the events detected by the Pierre Auger Observatory / Mestrado / Física / Mestre em Física
336

Développement et applications de détecteurs gazeux à micro-pistes pour la tomographie muonique / Development and applications of micro-pattern gaseous detectors for muon tomography

Bouteille, Simon 11 September 2017 (has links)
Cette thèse décrit les premiers essais de tomographie muonique par absorption et par déviation en utilisant des détecteurs Micromegas à haute granularité. Cette technique d'imagerie utilisant les rayons cosmiques gratuits, sans dangers et disponibles partout a démontré sa capacité à imager des objets de tailles variées. Afin de construire des outils compacts, précis, et portables, utiliser une voie d'électronique pour lire chaque motif de lecture est impossible. Pour éviter ce problème, des détecteurs multiplexés ont été conçus, testés et mis en situation dans différentes conditions. Il a été tiré parti des dernières améliorations concernant le détecteur Micromegas telles que le multiplexage génétique ou la lecture 2D par pistes sous une couche résistive. Les prototypes qui ont été fabriqués ont atteint une résolution de 300µm sur une surface d'un quart de mètre carré en ne nécessitant que 61 voies d'électronique. Grâce à ces détecteurs, des campagnes de prise de données ont été faites, à la fois dans l'environnement semi-contrôlé du centre CEA de Saclay et sur le plateau de Gizeh en Egypte. Ces deux campagnes ont permis d'imager avec succès le château d'eau du CEA Saclay ainsi que la pyramide de Khéops et ce malgré les conditions extrêmes que les télescopes à muon ont endurées. Des variations de température de plusieurs dizaines de Kelvin ont été enregistrées alors que l'acquisition de données se déroulait de manière stable, c'est-à-dire que les variations du gain n'impactaient pas le système d'auto déclenchement. Cette stabilité a été rendue possible grâce à un ajustement des hautes tensions vis à vis des conditions environnementales. Cela constitue la première mondiale concernant le fonctionnement d'un dispositif de reconstruction de trace à base de Micromégas en extérieur. En parallèle des expériences de muographie par déviation ont été menées. Un dispositif imageant des objets de petite taille est capable de distinguer divers matériaux sur une échelle de temps de l'ordre d'une journée. Une plus grande installation a permis d'imager un conteneur entier. La résolution du problème inverse a été faite en utilisant à la fois l'algorithme simple dit du PoCA ainsi que celui de maximisation de vraisemblance proposé par Schultz et son équipe. / This thesis describes the first attempts to perform both absorption and scattering muon tomography using high granularity Micromegas detectors. This imaging technique using the free, available and harmless cosmic ray muons radiation shows great possibilities to study various sized objects. In order to make compact and precise portable devices, using one channel of electronics per readout pattern is not possible. To avoid this problem multiplexed detectors have been designed, extensively tested and used in numerous conditions. Latest developments in Micromegas design have been used such as the genetic multiplexing and the 2D strip readout using a resistive layer. The prototypes made were able to achieve a 300µm resolution at the scale of 50cm while using only 61 channels of electronics. Using these detectors, muography data taking campaigns have been performed both in the semi-controlled environment of the Saclay site of CEA and in the wild of the Giza plateau in Egypt. These two campaigns succeeded in imaging the CEA Saclay water tower and the Khufu's pyramid despite the extreme conditions endured by the Micromegas muon telescopes. Large temperature variations of a few tens of Kelvin have been recorded together with a stable operation i.e. an even gain ensuring a steady self triggering system. This stability was achieved using high voltage variations with respect to the environmental conditions. Together with this very first worldwide operation of a Micromegas-based tracker outside a laboratory, scattering muographies have also been done. A small setup imaging handheld objects performed well in separating various materials in time scales of the order of the day while a bigger 1m² setup allowing the scan of a full container was successfully operated. The inversion of the ill-posed problem of the muon scattering was performed using the crude PoCA method and the maximum likelihood one described by Schultz et al.
337

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.
338

Studium vlivu ionizujícího záření na komunikační systémy umělých družic / Investigation of Ionizing Radiation Infuence to the Communication Systems of Satellites

Golubev, Martin January 2018 (has links)
This master thesis discuss about ionizing radiation, interaction with matter and effects on her. In the work is discussed differend types of interactions of directly ionizing radiation and indirectly ionizing radiation. Below is an overview of methods of shielding from all of types of ionizing radiation. Second part of this thesis discuss about single event effects in semiconductors which are cause by ionizing radiation. At the end is described design of measuring instrument included FPGA chips. This design is discused both from point of wiew hardware and software too.
339

Vliv radiace na vlastnosti polovodičových součástek / The effects of ionizing radiation on semiconductor devices properties

Yermalayeva, Darya January 2018 (has links)
This master’s thesis deals with the problematics of influence of ionizing radiation on semiconductor devices and their properties. The aim of the thesis is to analyze the different types of radiation that can occur in the areas of application of these components. In the second part, the degradation processes are explored, with emphasis on the influence caused by the radiation dose. Also, the displacement damage and SEE effects are described, but just slightly, because they are not part of this work. The third part describes the device design process and harmful effects, that have to be considered during the design phase. In the forth and the fifth parts of this work were done modeling of radiation effects (influence of dose rate, Single-Event Upset and Total Ionizing Dose) in PSpice program and was carried out the possibility of designing a simple dosimeter with silicon diode. In conclusion, the results of the thesis are summarized and evaluated.
340

Studium vlivu ionizujícího záření na komunikační systémy umělých družic / Investigation of Ionizing Radiation Infuence to the Communication Systems of Satellites

Golubev, Martin January 2018 (has links)
This master thesis discuss about ionizing radiation, interaction with matter and effects on her. In the work is discussed differend types of interactions of directly ionizing radiation and indirectly ionizing radiation. Below is an overview of methods of shielding from all of types of ionizing radiation. Second part of this thesis discuss about single event effects in semiconductors which are cause by ionizing radiation. At the end is described design of measuring instrument included FPGA chips. This design is discused both from point of wiew hardware and software too.

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