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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.
1

Modernizace vnitřního detektoru ATLAS / Modernizace vnitřního detektoru ATLAS

Mészárosová, Lucia January 2016 (has links)
The main goal of this master thesis is, at first, to describe upcoming upgrade of ATLAS experiment in CERN in Switzerland and to describe the principle of strip silicon detectors. Then it is measurement and analysis of data from laser tests with two lasers: red and infra-red. Last but not least goal is to document the method of measurement and analysis of laser tests for the future laser tests. The text of the thesis is divided into five chapters. The first chapter is dedicated to the research facility CERN, its present experiment ATLAS and future experiment ATLAS Upgrade. The second chapter explains properties of semiconductors and the principle of strip semiconductor detectors. The third chapter describes whole measurement layout: a lab for testing, equipment needed for the tests and the whole system functioning. In the fourth chapter there are actual results from the laser tests. The tests were done on two end-cap prototype modules for ATLAS Upgrade with strip silicon sensors using two lasers: red and infra-red. The last chapter briefly explains the functions of macros that were created for measuring and analysing data from laser tests.
2

An investigation of processing techniques and characterisation methods for 3D diamond detectors

Murphy, Steven January 2018 (has links)
In this thesis 3D diamond detectors were fabricated using an ultrafast femtosecond (120 fs) pulse length laser, with a 800nm wavelength, to induce a phase change of diamond to graphite to form electrodes in the diamond bulk. Graphitic electrodes, with diameters of O(um), were fabricated using a known processing technique and were enhanced further through the use of a Spatial Light Modulator (SLM), which is a new technology in this field. These detectors were subsequently characterised through the use of particle beams, and this work also presents methods for characterising such detectors: A pair of crossed polarisers to determine the stress induced by the electrodes on the diamond bulk; Raman spectroscopy to assess the relative quantity of diamond:graphite formed; Scanning Electron Microscopy (SEM) to image the starting (seed) and finishing (exit) sides of electrode formation; and current-voltage (I-V) measurements to calculate the electrical properties of the electrodes. These characterisation methods (alongside the use of particle beams) serve as a means to compare the two fabrication techniques and to determine the optimum fabrication parameters to produce 3D diamond detectors for use as tracking detectors in high luminosity environments such as those in the Large Hadron Collider (LHC). This work shows that using a higher beam energy and translation speed of the focal spot results in electrodes of lower electrical resistivity, which is an ideal characteristic for a tracking detector. These higher processing parameters also result in more graphitic structure on the seed and exit sides of the diamond, determined separately via Raman spectroscopy and SEM. An increased beam energy also results in larger electrode diameters, reducing the active area of the detector and inducing more stress in the diamond bulk. These measurements therefore indicate an upper limit on the fabrication parameters. A further study into these processing parameters shows the translation speed scales with the pulse repetition rate of the laser and allows for fast fabrication of 3D diamond detectors. Two devices were fabricated with and without the use of an SLM, with a more uniform detector response (through characterisation by particle beams), lower electrical resistivity, and more graphitic material observed for SLM-fabricated electrodes. The benefits of square and hexagonal cell structures were also investigated with both structures showing a similar response to particle beams. A lower charge sharing region is observed in hexagonal cells and indicates potentially different applications for these cell geometries. Transient Current Technique (TCT) measurements were also taken on both detectors, where faster charge collection and higher quality data were seen for the SLM-fabricated device. These measurements indicate a preference in the use of an SLM for the future fabrication of 3D diamond tracking detectors. These TCT measurements were then compared to simulations to extract the charge carrier properties in diamond. Only qualitative agreement was obtained, motivating further work in this area to fully understand the charge carrier dynamics and demonstrate the future viability of 3D diamond detectors.
3

Etude d'un détecteur pixel monolithique pour le trajectographe d'ATLAS auprès du LHC de haute luminosité / Study of a monolithic pixel detector for the ATLAS tracker at the High Luminosity LHC

Liu, Jian 27 May 2016 (has links)
Prévue pour 2024, une série d’améliorations doit être apportée au grand collisionneur d’hadrons du CERN (LHC) de manière à élargir son potentiel de découverte de nouvelle physique. Cette thèse se situe dans la perspective des études d’amélioration du détecteur ATLAS dans ce nouvel environnement, et concerne une nouvelle technologie monolithique HV/HR CMOS qui pourrait être utilisée pour les détecteurs de traces centraux pixélisés. Cette technologie a le potentiel de permettre la réduction de l’épaisseur des détecteurs, d'augmenter la granularité ainsi que de réduire les couts de production.Au sein de la collaboration HV/HR CMOS d’ATLAS, divers prototypes ont été développés en utilisant les technologies de différents partenaires industriels : GlobalFoundries (GF) BCDlite 130 nm et LFoundry (LF) 150 nm entre autres. Pour comprendre le comportement électrique et la capacité de détection de telles technologies, des simulations TCAD -Technology Computer Aided Design- en 2D et 3D ont été réalisées pour extraire le profil de la zone déplétée, la tension de claquage, la capacitance ainsi que la collection de charges ionisées des prototypes. Le développement de systèmes de test complexes et la caractérisation des prototypes HV/HR CMOS ont aussi été une partie du travail fourni pour cette thèse. Les programmes d’acquisition, en particulier pour ce qui concerne les tests sous protons ou auprès d’irradiateurs à rayons X, ainsi que les programmes de réglages de seuil ont été implémenté dans divers systèmes de test. Plusieurs versions des prototypes développés dans 3 technologies HV/HR CMOS différentes (AMS 0.18 μm HV, GF BCDlite 130nm et LF 150nm) ont été caractérisées. / A major upgrade to the Large Hadron Collider (LHC), scheduled for 2024 will be brought to the machine so as to extend its discovery potential. This PhD is part of the ATLAS program and aims at studying a new monolithic technology in the framework of the design of an upgraded ATLAS inner tracker. This new type of sensor is based on a HV/HR CMOS technology, which would potentially offer lower material budget, reduced pixel pitch and lower cost with respect to the traditional hybrid pixel detector concept.Various prototypes have been developed using different HV/HR CMOS technologies from several industrial partners, within the ATLAS HV/HR collaboration, for instance Global Foundry (GF) BCDlite 130 nm and LFoundry (LF) 150 nm. In order to understand the electric behavior and the detection capabilities of these technologies, 3D and 2D Technology Computer Aided Design (TCAD) simulations have been performed to extract the depletion zone profile, the breakdown voltage, the leakage current, the capacitance as well as the charge collection of the prototypes. Test setup developments and characterizations of the HV/HR CMOS prototypes were also part of this thesis. The data acquisition programs, in particular dedicated to the proton test beams, X-ray sources and threshold tuning, have been implemented into various test setups. Several HV/HR CMOS prototypes developed in three HV/HR technologies, AMS 0.18 µm HV, GF BCDlite 130 nm and LF 150 nm, have been characterized.

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