Dissertations / Theses on the topic 'Atlas data'
To see the other types of publications on this topic, follow the link: Atlas data.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Atlas data.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Parker, Vincent. "Statistical analysis of bird atlas data from Swaziland." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/20195.
Full textAbstract:
The question of what determines the observed geographical distributions of animal species is one of great interest to natural scientists. In general terms, these distributions are known to be related to a number of environmental factors, but the nature of the relationships and the relative importance of the different factors remain poorly understood. This investigation sets out to obtain more insight into these questions by using statistical methods to explore the relationships between the observed geographical distributions of bird species in Swaziland and a number of environmental variables. In 1985 I set out to compile a bird atlas of Swaziland. Data were accumulated between 1985 and 1991 and the bird atlas submitted to a publisher in May 1993. The text of the bird atlas is included here as Appendix 2 because it provides the essential background to this dissertation. The introductory section of the atlas includes a description of the data gathering process. The analysis included in the bird atlas was aimed at a popular readership and was not intended to form part of an academic dissertation Chapter 1 describes the use of logistic regression to investigate the relationships between the bird distribution patterns and a set of environmental variables and to predict the distributions. Chapter 2 describes the results of applying the methods described in Chapter 1 for all of the bird species for which data were available. Because this paper was aimed at a different readership, some repetition of material contained in Chapter 1 was unavoidable. In Chapter 3, biplot techniques were used to obtain a graphical representation of the bird atlas data.
2
Öhman, Henrik. "Analysis of early data from the ATLAS experiment towards H+ searches." Thesis, Uppsala universitet, Högenergifysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159414.
Full textAbstract:
In the ATLAS experiment software plays a central role in data taking, reconstruction, and analysis. This thesis presents a set of analysis algorithms written for the ATLAS software framework Athena, towards H+ searches in the τ+jets channel. Data recorded by the ATLAS experiment for 900 GeV proton-proton collisions from 2009 and 7 TeV proton-proton collisions from 2010 are analyzed with these algorithms and compared to Monte Carlo. A search for top quarks is performed on 36 pb-1 of data, and the results are found to agree well with Monte Carlo.
3
Price, Darren David. "Studies of quarkonium production and polarisation with early data at Atlas." Thesis, Lancaster University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527159.
Full text
4
Zhang, Jia Ph D. Massachusetts Institute of Technology. "The constant atlas : mapping public data for individuals and their cities." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119075.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 131-136).
Over the past ten years the ability of institutions and businesses to capture, aggregate, and process an individual's data has grown significantly as digital technology has increasingly integrated into our daily lives. In the urban informatics context and in computational social science, projects use data collected about our behavior in the urban environment to solve problems including traffic congestion and public safety, the creation of targeted advertising, and the development of entire neighborhoods. Some projects using aggregate data may ultimately benefit individuals by making improvements to their environment at large. Although individuals are the source of aggregate information, an individual citizen often does not directly engage with the data collected about them. The research contained in this dissertation explores a series of visualization experiments concerning direct engagement between citizens and public datasets such as the U.S.Census. In order for such visualizations to be effective, they not only have to efficiently communicate data, but must also be intuitive, evocative, and utilize narratives presented from the user's perspective. In this dissertation I address the question: How can we design visualizations which inform daily interaction between individuals and public data about their environment? To answer this question, the dissertation introduces 4 sets of maps: (1) the Powers Map and Scopes Map contextualizes Census data(American Community Survey) by invoking changes in scale, (2) the Sightline Map and Cross Section Map use a person's physical experiences to orient Census data, (3) the Filtered Satellite Maps give qualitative comparisons of conditions described by Census tables, and (4) the Personal History Map leverages an individual's geospatial history to filter Census data. These 4 map groups share the goal of allowing us, as individuals, to use public data to design our own experiences within our environments and to make use of public data directly on our own behalf.
by Jia Zhang.
Ph. D.
5
Agius, Nicola Kristina. "Dust in Early-Type Galaxies using Herschel-ATLAS and GAMA data." Thesis, University of Central Lancashire, 2014. http://clok.uclan.ac.uk/10715/.
Full textAbstract:
This work investigates the properties of Early-Type Galaxies (ETGs; elliptical and lenticulars) containing thermal dust emission, with aims of linking the formation and evolution of these galaxies with their current dust properties. Three different proxies for morphology are considered for selecting ETGs, and these are tested against three sets of visually classified galaxies. We find that classifying ETGs as those galaxies in the optical Red Sequence results in samples with ≳35% contamination by late-types, and ≲82% completeness. Concentration and Sérsic index proxies result in slightly improved contamination levels of ≳30% and ~60-70% completeness. These results lead to the conclusion that morphological proxies cannot be used to create fully robust samples of ETGs. Therefore, we choose to use visual inspection to identify ETGs at low redshifts.
6
Beermann, Thomas [Verfasser]. "A popularity prediction and dynamic data replication study for the ATLAS distributed data management / Thomas Beermann." Wuppertal : Universitätsbibliothek Wuppertal, 2017. http://d-nb.info/1136872981/34.
Full text
7
Klemetti, Miika. "Search for Higgs bosons beyond the standard model in early ATLAS data." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104496.
Full textAbstract:
Higgs bosons are present in many extensions of the Standard Model, yet we are still waiting for the experimental confirmation of their existence. This thesis discusses Minimal and Next-to Minimal Supersymmetric Models, and presents searches for leptonic Higgs boson decays in channels that may provide the first unambiguous evidence of Higgs physics beyond the Standard Model. The channels considered are1 : gg→a1, gg→h1→2a1, H+→τν, and H+→a1W+, where a1→µµ and τ→ℓνν . A full data analysis is presented for gg→a1→µµ channel, while sensitivity prospects are discussed for the other channels. For the data analysis, we consider a data set with an integrated luminosity of 39 pb−1 collected by the ATLAS Detector at the Large Hadron Collider in 2010, operating at the centre of mass energy of √s = 7 TeV. As we observe no evidence for a signal in the gg→a1 channel, we set a model independent 95% confidence level upper limit on Higgs production cross section and branching ratio: σgg→a1×B(a1→µµ). This result represents the first measurement of σgg→a1×B(a1→µµ) in the world, and improves on the current experimental constraints on the Higgs sector beyond the Standard Model.Les bosons de Higgs sont présents dans de nombreuses extensions du Modèle Standard, mais nous sommes toujours en attente de la confirmation exprimentale de leur existence. Cette thèse traite des modèles communs supersymetriques, et presente les recherches de désintégrations leptoniques du boson de Higgs dans les processus qui peuvent fournir la premiere preuve, sans equivoque, du Higgs au-dela du Modèle Standard. Les processus considérés sont: gg→a1, gg→h1→2a1, H+→τν,et H+→a1W+, avec a1→µµ et τ→ℓνν. La sensibilité des perspectives sont discutées pour les trois derniers, alors qu'une analyse de données complète est présentée pour le premier processus. Nous considérons un ensemble de données avec une luminosité integrée de 39 pb−1 collectées par le detecteur ATLAS au Large Hadron Collider en 2010, operant au centre de masse de √s = 7 TeV. Comme on n'observe pas de signal, nous avons mis une limite superieure sur la section efficace de production de Higgs et du rapport de branchement: σgg→a1×B(a1→µµ). Ce résultat représente une toute première mesure de σgg→a1×B(a1→µµ) dans le monde, et s'améliore sur les contraintes expérimentales courantes sur le secteur de Higgs au delà du Modèle Standard.
8
Flowerdew, M. I. chael James. "Standard model Z/gamma to ee production in early data at Atlas." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526791.
Full text
9
Argyropoulos, Spyridon. "Measurement of the ttbb production cross-section with 8 TeV ATLAS data." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17476.
Full textAbstract:
Diese Dissertation beschreibt die Messung des Wirkungquerschnitts für die Produktion von ttbb in Protonkollisionen mit einer Schwerpunktsenergie von √s = 8 TeV. Der verwendete Datensatz entspricht einer integrierten Luminosität von 20.3/fb. Der Wirkungsquerschnitt wurde aus der Anzahl der Signalereignisse bestimmt, die durch harte Schnitte insbesondere auf genau 4 identifizierten b-jets, selektiert wurden, was zu einer hohen Reinheit des Signals führt. Bei der Messung wurden die präzisesten Kalibrierungen von der Jet-Energieskala und der b-jet Effizienz benutzt. Die Messung wurde in einem Referenzphasenraum durchgeführt, der daraufhin optimiert wurde, die Abhängigkeit von der Modellierung zu minimisieren. Der gemessene Wirkungsquerschnitt beträgt 18.9 ± 3.5 (stat)+5.6 (sys) ± 0.6 (Lumi) fb oder, nachdem der Beitrag von ttH(bb) und ttZ(bb) abgezogen wurde: 17.8 ± 3.5 (stat)+5.9 (sys) ± 0.6 (Lumi) fb. Das Ergebnis wurde mit einer Vielzahl von theoretischen Vorhersagen verglichen, einschließlich NLO-Berechnungen mit Partonschauern und einer Reihe von Modellen die sich in der Beschreibung der Gluon Spaltung unterscheiden. Es wurde gezeigt, dass das exstremste Model den Wirkungsquerschnitt überschätzt und dass die Messung die Vorhersagen bevorzugt, die mit einer niedrigen Renormierungs- und Faktorisierungsskala, berechnet wurden.This thesis presents the measurement of the ttbb production cross-section, using a dataset of 20.3/fb of pp collisions collected with the ATLAS detector at 8 TeV. The measurement is based on a cut-and-count method, using a sample of events with exactly four b-tagged jets, which is shown to have a high purity in signal events. The measurement exploits the most precise jet energy scale and b-tagging calibrations and is performed in a fiducial phase space that is designed to minimize the model dependence of the measurement. The fiducial cross-section is measured to be 18.9 ± 3.5 (stat)+5.6 (sys) ± 0.6 (Lumi) fb or subtracting the contribution from ttH(bb) and ttZ(bb) final states, 17.8 ± 3.5 (stat)+5.9 (sys) ± 0.6 (Lumi) fb. The result is compared with a multitude of theoretical predictions, including different NLO calculations matched to a parton shower, which constitute the most precise predictions available to date, as well as with a series of models that differ in the description of the gluon splitting to b-quarks. It is shown that the most extreme gluon splitting model overestimates the observed rate of ttbb production and that the measurement favors calculations performed with renormalization/factorization scales which are softer than the scales usually employed in similar calculations.
10
Muschter, Steffen Lothar. "Readout link and control board for the ATLAS Tile Calorimeter upgrade." Doctoral thesis, Stockholms universitet, Fysikum, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-116258.
Full textAbstract:
The Large Hadron Collider (LHC) at the CERN laboratory was designed to study the elementary particles and forces and search for new physics. Detectors at LHC were designed to observe proton-proton collisions with center of mass energies up to 14 TeV, seven times higher than previously possible. One of the largest of these is the general purpose detector ATLAS. After almost 20 years of planning and construction, LHC and its detectors were finished in 2008. Since then ATLAS has produced valuable data, which contributed to the discovery of the 1964 postulated Higgs-particle and thus to the Nobel prize in physics in 2013. To expand the searches, LHC and its detectors will undergo several upgrades to the increase luminosity at least by a factor of 5 and to exploit the full potential of the machine. In order to adapt the detector to the resulting increasing event rates and radiation levels, new electronics have to be developed. This thesis describes the development process of a new upgraded digital readout system for one of the sub-detectors in ATLAS, the scintillating Tile Calorimeter (TileCal), and more specifically one of its key components, the high-speed data link DaughterBoard. Starting from the idea of transferring all recorded information of the detector using high speed serial optical links and the concept of using re-programmable logic for the readout electronics, completely new on-detector electronics were designed to be used as a core component for communication, control and monitoring. The electronics was tested, electrical characterized and proven to work in a setup similar to the upgraded readout electronics. The DaughterBoard is the Stockholm University contribution to the ATLAS upgrade in 2023.
11
Dopke, Jens [Verfasser]. "Commissioning of the ATLAS Pixel Detector optical data transmission and studies for readout of the ATLAS IBL and future trackers / Jens Dopke." Wuppertal : Universitätsbibliothek Wuppertal, 2012. http://d-nb.info/1024305066/34.
Full text
12
Schott, Matthias. "Study of the Z Boson Production at the ATLAS Experiment with First Data." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-73164.
Full text
13
Hankache, Robert. "Jet calibration, cross section measurements and New Physics searches with the ATLAS experiment within the Run 2 data." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS610.
Full textAbstract:
Le Modèle Standard est la théorie actuelle utilisée pour décrire les particules élémentaires et leurs interactions fondamentales (à l'exception de la gravité). Ma thèse au sein de l'expérience ATLAS met ce modèle sous test utilisant des objets appelés jets, pour étudier l’état final de particules qui interagissent à travers la force forte. Tout d'abord, j'ai contribué à une méthode d'étalonnage de jet visant à calibrer l'échelle d'énergie des jets dans la région avant du détecteur par rapport à la région centrale. J'ai amélioré la calibration en la rendant plus rapide et plus précise. Ensuite, j'ai travaillé sur une analyse de recherche de la nouvelle physique en utilisant des événements à deux jets. Le Modèle Standard prédit une distribution lisse de la masse invariante des bi-jets, d'où la recherche d'une bosse pouvant provenir d’une nouvelle particule. Comme aucune bosse significative n'est détectée, nous avons mis des limites sur des signaux prédits par des théories au delà du Modèle Standard. Enfin, j'ai développé une nouvelle analyse de physique mesurant la section efficace différentielle du jet ayant le plus haut moment transverse en fonction du moment transverse et de la rapidité. Le défi consistait à factoriser les effets du détecteur (résolution et acceptance) de l'observable, ce que j'ai fait en utilisant une nouvelle technique de déploiement. J'ai également travaillé sur le calcul des prédictions théoriques qui était très difficile à réaliser et nécessitait la mise en place de régularisations spéciales. La mesure et les prédictions sont ensuite comparées et des tensions, qui s’expliquent par la complexité de la prédiction, sont observéesThe Standard Model is the current theory used to describe the elementary particles and their fundamental interactions (except the gravity). My PhD within the ATLAS experiment put this model under test using objects called jets, to study final state particles that interact through the strong force. First, I contributed to a method of jet calibration aiming at calibrating the energy scale of jets in the forward region of the detector with respect to central region. I improved the calibration by making it faster and more precise. Next, I worked on a search analysis of new physics using events with two jets. The Standard Model predicts a smooth distribution of the invariant mass of di-jets, hence we search for a bump which could come from a new particle. Since no significant bump is found, we put limits on signals as predicted by Beyond Standard Model theories and on model-independent signals. Last, I developed a new physics analysis measuring the leading (highest in transverse momentum) jet differential cross-section as a function of transverse momentum and rapidity. The challenge was to factorize the detector effects (resolution and acceptance) from the observable, which I did using a new unfolding technique. I also worked on the theoretical predictions calculation which was very challenging to perform and needed the implementation of special regularizations. The measurement and the predictions are then compared and tensions are observed due to the difficulties of theoretical predictions calculation
14
Jahan, Farzana. "New insights into Bayesian models for spatial data." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/212622/1/Farzana%20Jahan%20Thesis.pdf.
Full textAbstract:
Spatial data is often aggregated into small area. It is challenging to analyse these data. Two new statistical techniques were developed to tackle these challenges. Bayesian meta-analysis models were used to unveil geographic disparities in cancer using the Australian Cancer Atlas. More flexible Bayesian Empirical Likelihood models were used to analyse more complex data including COVID19 deaths. Both methods provided new insights into the analysis of spatial data.
15
Fisher, Matthew J. "The search for low scale technicolor in the Z + γ channel in 7 TeV ATLAS data." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343620633.
Full text
16
Lane, Jenna Louise. "Prospects for charged Higgs Boson searches at the Large Hadron Collider with early ATLAS data." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/prospects-for-charged-higgs-boson-searches-at-the-large-hadron-collider-with-early-atlas-data(517a7a6c-02a0-4ccb-ab2f-2e483de3c972).html.
Full text
17
Tanwar, Rajendra Singh. "Design and development of thematic maps for census atlas for the Brisbane City Council." Thesis, Queensland University of Technology, 1995.
Find full text
18
Eckardt, Christoph. "Jet activity in top-quark events at √s = 13 TeV using 3.2 fb-1 data collected by the ATLAS detector." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21053.
Full textAbstract:
In dieser Arbeit wird die Messung des normalisierten differentiellen Wechselwirkungsquerschnitts von Top Quark Produktionen mit zusätzlichen Jets präsentiert. Es werden Proton-Proton Kollisionsdaten des ATLAS Experiments am Large Hadron Collider bei einer Schwerpunktsenergie von 13 TeV mit einer Luminosität von 3.2 fb-1 verwendet. Die Top Quark Ereignissen werden durch ein entgegengesetzt geladenes Elektron-Muon Paar und zwei b-tagged Jets selektiert. Der differentielle Wechselwirkungsquerschnitt wird als Funktion von Observablen, die sensitiv auf zusätzliche Jets sind, gemessen: der Jetmultiplizität, des transversalen Impulses der zusätzlichen Jets, der Summe der transversalen Impulse aller Objekte im Ereignis und räumlichen Korrelationen zwischen den zwei Jets mit dem größten Impulsen. Die gemessenen Daten werden auf Teilchen-Level korrigiert und mit verschiedenen Vorhersagen für detailierte Studien des Monte Carlo QCD Models verglichen.In this thesis, the measurement of the normalised differential cross-sections of top quark pair production in association with jets using 3.2 fb-1 of proton-proton col- lision data at a centre-of-mass energy of 13 TeV by the ATLAS experiment at the LHC are presented. Jets are selected from top events which are defined by an opposite-charge electron-muon pair and two b-tagged jets in the final state. The cross-sections are measured as functions of several observables are sensitive to ad- ditional jets: jet multiplicities, transverse momentum of additional jets, transverse momentum sum of all objects in the event and spatial correlations of the two high- est momentum additional jets. The data are corrected to obtain particle-level fidu- cial cross-section. The resulting measurements are compared to several predictions allowing detailed studies of Monte Carlo QCD modelling.
19
Gandrajula, Reddy Pratap. "Study of run time errors of the ATLAS Pixel detector in the 2012 data taking period." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2499.
Full textAbstract:
The high resolution silicon Pixel detector is critical in event vertex reconstruction and in particle track reconstruction in the ATLAS detector. During the pixel data taking operation, some modules (Silicon Pixel sensor +Front End Chip+ Module Control Chip (MCC)) go to an auto-disable state, where the Modules don't send the data for storage. Modules become operational again after reconfiguration. The source of the problem is not fully understood. One possible source of the problem is traced to the occurrence of single event upset (SEU) in the MCC. Such a module goes to either a Timeout or Busy state. This report is the study of different types and rates of errors occurring in the Pixel data taking operation. Also, the study includes the error rate dependency on Pixel detector geometry.
20
Aad, G., Richard Brenner, Claus P. Buszello, Tord Ekelöf, Mattias Ellert, Arnaud Ferrari, and L. Zwalinski. "Electron performance measurements with the ATLAS detector using the 2010 LHC proton-proton collision data." Uppsala universitet, Högenergifysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-175052.
Full textAbstract:
Detailed measurements of the electron performance of the ATLAS detector at the LHC are reported, using decays of the Z, W and J/psi particles. Data collected in 2010 at root s = 7 TeV are used, corresponding to an integrated luminosity of almost 40 pb(-1). The inter-alignment of the inner detector and the electromagnetic calorimeter, the determination of the electron energy scale and resolution, and the performance in terms of response uniformity and linearity are discussed. The electron identification, reconstruction and trigger efficiencies, as well as the charge misidentification probability, are also presented.ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-012-1909-1
21
Nellist, Clara. "Characterisation and beam test data analysis of 3D silicon pixel detectors for the ATLAS upgrade." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/characterisation-and-beam-test-data-analysis-of-3d-silicon-pixel-detectors-for-the-atlas-upgrade(22a82583-5588-4675-af5c-c3595b4ceb38).html.
Full textAbstract:
3D silicon pixel detectors are a novel technology where the electrodes penetrate the sili- con bulk perpendicularly to the wafer surface. As a consequence the collection distance is decoupled from the wafer thickness resulting in a radiation hard pixel detector by design. Between 2010 and 2012, 3D silicon pixel detectors have undergone an intensive programme of beam test experiments. As a result, 3D silicon has successfully qualified for the ATLAS upgrade project, the Insertable B-Layer (IBL), which will be installed in the long-shutdown in 2013-14. This thesis presents selected results from these beam test studies with 3D sensors bonded to both current ATLAS readout cards (FE-I3) and newly developed readout cards for the IBL (FE-I4). 3D devices were studied using 4 GeV positrons at DESY and 120 GeV pions at the SPS at CERN. Measurements presented include tracking efficiency (of the whole sensor, the pixel and the area around the electrodes), studies of the active edge pixels of SINTEF devices and cluster size distributions as a function of incident angle for IBL 3D design sensors. A simulation of 3D silicon sensors in an antiproton beam test for the AEgIS experiment, with comparison to experimental results and a previous simulation, are also presented.
22
Goudet, Christophe. "Calibration of the Electromagnetic Calorimeter of the ATLAS Experiment and Application to the Measurement of (BE)H Boson Couplings in the Diphoton Channel with Run 2 Data of the LHC." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS304/document.
Full textAbstract:
La découverte du boson de Higgs en 2012 a été un des principaux succès du run 1 du LHC. Une ère de mesures de précision a alors débuté à la recherche de déviations par rapport au Modèle Standard (MS), qui seraient des indices quant à la physique au-delà du MS.Ce manuscrit s'intéresse en premier lieu à l'étalonnage du calorimètre électromagnétique de l'expérience ATLAS. L'étape finale de cet étalonnage utilise la distribution en masse du boson Z pour corriger l'énergie mesurée des électrons et des photons. Des recommandations pour le démarrage du run 2 ont été produites afin de fournir des constantes de correction pour aux premières analyses. Les corrections utilisant les données du run 2 ont également été mesurées. Les performances de l'étalonnage du run 1 ont été atteintes puis améliorées : l'incertitude systématique sur le terme constant de la résolution du calorimètre électromagnétique, dominante pour la mesure des couplages du boson de Higgs au run 1, a été divisée par 3. La mesure des couplages du boson de Higgs consiste en la mesure de la forme du signal résonnant sur un bruit de fond décroissant. Cette mesure est effectuée de manière corrélée entre différentes catégories, optimisées pour différents modes de production à travers l'identification d'objets produits avec le boson de Higgs. Les résultats ont été obtenus à partir de 36 fb$^{-1}$ de données récoltées en 2015 et 2016 à une énergie de $sqrt{s}$=13 TeV. Le rapport ($mu$) de la mesure de la section efficace inclusive du boson de Higgs sur sa valeur dans le MS a été mesuré. Aucune déviation significative par rapport au MS n'a été observée. $$mu = 0.99 pm 0.14$$Les rapports des principaux modes de production ont également été mesurés :$$mu_{ggH} = 0.80 pm 0.18$$$$mu_{VBF} = 2.1 pm 0.66$$$$mu_{VH} = 0.7 pm 0.85$$$$mu_{ttH+tH} = 0.5 pm 0.62$$The discovery of the Higgs boson was a major success of the run 1 of the LHC. The era of precision measurements began as any deviation from the expected Standard Model value would be a direct hint of new physics beyond the standard model. This thesis has a first focus on the calibration of the electromagnetic calorimeter of the ATLAS experiment. The final step of this calibration uses the knowledge of the line shape of the Z boson in order to correct the measured energy of electrons and photons. Recommendations for the beginning of run 2 have been given to provide calibration constants for early analyses. Run 2 calibration constants have been computed and the performances of run 1 have been reached and improved : the systematic uncertainty on the resolution constant term of the electromagnetic calorimeter, which was dominant for the Higgs boson couplings measurement at run 1, has been divided by a factor 3.The measurement of the H boson couplings consists in measuring the shape of the resonant signal over a smooth decreasing background in categories optimized for various processes, by tagging the objects produced in association with the Higgs boson. The results are based on 36 fb$^{-1}$ of data recorded in 2015 and 2016 at $sqrt{s}$=13 TeV. The ratio of the measured production cross-sections of the Higgs boson over the SM expected value ($mu$) has been measured. No significant deviation with respect to the SM has been observed.$$mu = 0.99 pm 0.14$$The ratios of the main production processes have also been measured:$$mu_{ggH} = 0.80 pm 0.18$$$$mu_{VBF} = 2.1 pm 0.66$$$$mu_{VH} = 0.7 pm 0.85$$$$mu_{ttH+tH} = 0.5 pm 0.62$$
23
Veatch, Jason Robert. "A Search For New Physics Using tt(bar) Resonances in the Lepton Plus Jets Channel at √(s) = 8 TeV in 20 fb⁻¹ of pp Collision Data at the ATLAS Experiment." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/578734.
Full textAbstract:
Many Beyond Standard Model theories predict particles that couple strongly to top/anti-top quark pairs. This makes tt(bar) a promising signature for new physics searches. The analysis presented in this dissertation uses 20.3 fb⁻¹ of √s = 8 TeV pp collision data from the ATLAS experiment to search for evidence of new physics in the single-lepton plus jets tt(bar) decay channel. This is done by requiring one electron or muon, large missing transverse momentum and additional hadronic jets. The tt(bar) system is reconstructed using techniques optimized for either resolved or boosted event topologies. The results of the analysis are used to set upper limits on the production cross-section times branching ratio for heavy resonances decaying to tt(bar). These limits are interpreted in the context of several benchmark models including the leptophobic topcolor Z', the Randall-Sundrum Kaluza-Klein gluon (gKK), the Randall-Sundrum Kaluza-Klein graviton (GKK) and a spin-0 scalar particle.
24
Lama, Luca. "Development and testing of the atlas ibl rod pre production boards." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/6283/.
Full textAbstract:
Il lavoro di questa tesi riguarda principalmente la progettazione, simulazione e test di laboratorio di tre versioni successive di schede VME, chiamate Read Out Driver (ROD), che sono state fabbricate per l'upgrade del 2014 dell'esperimento ATLAS Insertable B-Layer (IBL) al CERN. IBL è un nuovo layer che diverrà parte del Pixel Detector di ATLAS.
Questa tesi si compone di una panoramica descrittiva dell'esperimento ATLAS in generale per poi concentrarsi sulla descrizione del layer specifico IBL. Inoltre tratta in dettaglio aspetti fisici e tecnici: specifiche di progetto, percorso realizzativo delle schede e test conseguenti.
Le schede sono state dapprima prodotte in due prototipi per testare le prestazioni del sistema. Queste sono state fabbricate al fine di valutare le caratteristiche e prestazioni complessive del sistema di readout. Un secondo lotto di produzione, composto di cinque schede, è stato orientato alla correzione fine delle criticità emerse dai test del primo lotto.
Un'indagine fine e approfondita del sistema ha messo a punto le schede
per la fabbricazione di un terzo lotto di altre cinque schede. Attualmente la produzione è finita e complessivamente sono state realizzate 20 schede definitive che sono in fase di test.
La produzione sarà validata prossimamente e le 20 schede verranno consegnate al CERN per essere inserite nel sistema di acquisizione dati del rivelatore.
Al momento, il Dipartimento di Fisica ed Astronomia dell'Università di Bologna è coinvolto in un esperimento a pixel solamente attravers IBL descritto in questa tesi.
In conclusione, il lavoro di tesi è stato prevalentemente focalizzato sui test delle schede e sul progetto del firmware necessario per la calibrazione e per la presa dati del rivelatore.
25
Radovanovic, Lidija. "Data-driven QCD background estimation to W production in association with jets using the ATLAS detector." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/23466.
Full textAbstract:
A preliminary analysis was conducted using data from the proton-proton collisions at p s = 8 TeV recorded by the ATLAS experiment, corresponding to an integrated luminosity of approximately 18.9 ƒƅ⁻¹. It has been performed to extract the fraction of QCD events in the chosen phase space for the W boson production in association with jets. A data-driven technique was developed for measuring the QCD background. The fraction of QCD events in the signal region was estimated in exclusive jet multiplicities by performing an extended likelihood fit on the Emiss T distribution in data. The fraction of QCD events ranges 2:9 ± 0:01% for the zero jet bin and increases to 10:74 ± 0:11% for the two jet bin.The fraction of QCD events decreases with increasing jet multiplicity. Using the results from the fit, some important kinematic distributions have been made. The overall agreement between the data and Monte Carlo simulation is vastly improved by including the data-driven QCD background estimate. This agreement could be further improved by using a data-driven tt estimate where the tt MC tends to overestimate the amount of events in the higher jet multiplicities.
26
Tashiro, Takuya. "Search for single production of Vector Like Quarks using the LHC pp collision data at √s=13 TeV collected with the ATLAS detector." Kyoto University, 2019. http://hdl.handle.net/2433/242601.
Full text
27
Lapoire, Cécile. "Mise en oeuvre de l'étiquetage des jets issus de quarks beaux dans l'exprérience ATLAS au LHC." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX22071/document.
Full textAbstract:
Le Modèle Standard de la physique des particules prédit l'existence du boson de Higgs,dont le canal de désintégration privilégié à basse masse est la production de paires de quarks beaux. L'identification des jets issus de tels quarks dans le détecteur ATLAS, situé sur l'anneau du LHC, tient donc un rôle majeur dans la physique des particules moderne.Dans ce document, un aperçu des méthodes d'étiquetage de ces jets b utilisées dans ATLAS ainsi que l'optimisation d'un algorithme en particulier, JetProb, sont présentés. La préparation à la mesure de l’efficacité de ces algorithmes dans les données est également développée. Enfin, après la prise de données à 900 GeV au centre de masse puis à l'énergie record de 7 TeV en 2009-2010, les premiers résultats concernant l'étude des traces chargées et la mise en place de l'étiquetage des jets b dans les données ont été obtenus et sont rassemblés ici. La comparaison avec la simulation montre un bon accord et les premiers candidats jets b et événements top observés sont étudiésThe Standard Model of particle physics predicts the existence of the Higgs boson,which preferentially decays to b quark pairs at low mass. The identification of jets stemming from such quarks in the ATLAS detector, placed at the LHC, is thus one of the keysto modern particle physics.In this document, an overview of the b-tagging methods used in ATLAS as well as the optimization of a specific algorithm, JetProb, are presented. The preparation to the measurement of these algorithms efficiency in data is also developed. Finally, after the first datataking at 900 GeV and then at the record energy of 7 TeV in 2009-2010, the first results on charged track studies and b-tagging commissioning were obtained and are gathered together here. Comparison with simulation shows a good agreement and the first b-jet and top events candidates are studied
28
El, Haje Noura. "A heterogeneous data-based proposal for procedural 3D cities visualization and generalization." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30238.
Full textAbstract:
Ce projet de thèse est né d'un projet de collaboration entre l'équipe de recherche VORTEX/ Objets visuels: de la réalité à l'expression (maintenant REVA: Réel Expression Vie Artificielle) à l'IRIT : Institut de Recherche en Informatique de Toulouse d'une part et de professionnels de l'éducation, entreprises et entités publiques d'autre part. Le projet de collaboration SCOLA est essentiellement une plate-forme d'apprentissage en ligne basée sur l'utilisation des jeux sérieux dans les écoles. Il aide les utilisateurs à acquérir et à repérer des compétences prédéfinies. Cette plate-forme offre aux enseignants un nouvel outil flexible qui crée des scénarios liés à la pédagogie et personnalise les dossiers des élèves. Plusieurs contributions ont été attribuées à l'IRIT. L'une d'elles consiste à suggérer une solution pour la création automatique d'environnements 3D, à intégrer au scénario du jeu. Cette solution vise à empêcher les infographistes 3D de modéliser manuellement des environnements 3D détaillés et volumineux, ce qui peut être très coûteux et prendre beaucoup de temps. Diverses applications et prototypes ont été développés pour permettre à l'utilisateur de généraliser et de visualiser son propre monde virtuel principalement à partir d'un ensemble de règles. Par conséquent, il n'existe pas de schéma de représentation unique dans le monde virtuel en raison de l'hétérogénéité et de la diversité de la conception de contenus 3D, en particulier des modèles de ville. Cette contrainte nous a amené à nous appuyer largement dans notre projet sur de vraies données urbaines 3D au lieu de données personnalisées prédéfinies par le concepteur de jeu. Les progrès réalisés en infographie, les capacités de calcul élevées et les technologies Web ont largement révolutionné les techniques de reconstruction et de visualisation des données. Ces techniques sont appliquées dans divers domaines, en commençant par les jeux vidéo, les simulations et en terminant par les films qui utilisent des espaces générés de manière procédurale et des animations de personnages. Bien que les jeux informatiques modernes n'aient pas les mêmes restrictions matérielles et de mémoire que les anciens jeux, la génération procédurale est fréquemment utilisée pour créer des jeux, des cartes, des niveaux, des personnages ou d'autres facettes aléatoires uniques sur chaque jeu. Actuellement, la tendance est déplacée vers les SIG: Systèmes d'Information Géographiques pour créer des mondes urbains, en particulier après leur mise en œuvre réussie dans le monde entier afin de prendre en charge de nombreuses domaines d'applications.[...]This thesis project was born from a collaborative project between the research team VORTEX / Visual objects: from reality to expression (now REVA: Real Expression Artificial Life) at IRIT: Institute of Research in Computer Science Toulouse on the one hand and education professionals, companies and public entities on the other.The SCOLA collaborative project is essentially an online learning platform based on the use of serious games in schools. It helps users to acquire and track predefined skills. This platform provides teachers with a new flexible tool that creates pedagogical scenarios and personalizes student records. Several contributions have been attributed to IRIT. One of these is to suggest a solution for the automatic creation of 3D environments, to integrate into the game scenario. This solution aims to prevent 3D graphic designers from manually modeling detailed and large 3D environments, which can be very expensive and take a lot of time. Various applications and prototypes have been developed to allow the user to generalize and visualize their own virtual world primarily from a set of rules. Therefore, there is no single representation scheme in the virtual world due to the heterogeneity and diversity of 3D content design, especially city models. This constraint has led us to rely heavily on our project on real 3D urban data instead of custom data predefined by the game designer. Advances in computer graphics, high computing capabilities, and Web technologies have revolutionized data reconstruction and visualization techniques. These techniques are applied in a variety of areas, starting with video games, simulations, and ending with movies that use procedurally generated spaces and character animations. Although modern computer games do not have the same hardware and memory restrictions as older games, procedural generation is frequently used to create unique games, cards, levels, characters, or other random facets on each. Currently, the trend is shifting towards GIS : Geographical Information Systems to create urban worlds, especially after their successful implementation around the world to support many areas of applications. GIS are more specifically dedicated to applications such as simulation, disaster management and urban planning, with a great use more or less limited in games, for example the game "Minecraft", the latest version offers a map using real world cities Geodata in Minecraft.[...]
29
Mehlhase, Sascha. "Development of a data-driven algorithm to Determine the W+Jets Background in tt - events in ATLAS." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2010. http://dx.doi.org/10.18452/16193.
Full textAbstract:
Die Physik des Top-Quarks ist eine Schlüsselkomponente im Forschungsprogramm des ATLAS-Experiments am CERN. In dieser Arbeit werden Untersuchungen zur Leistungfähigkeit von Jet-Triggern für Top-Quark-Ereignisse präsentiert und zwei datenbasierte Methoden zur Abschätzung der Multijet-Triggereffizienz und des W+Jets-Untergrundes in Top-Quark-Ereignissen in ATLAS eingeführt. In einer tag-and-probe Methode, basierend auf einer einfachen und allgemeinen Ereignisselektion und einem hochenergetischen Lepton als Tag, wird die Möglichkeit zur Bestimmung der Multijet-Triggereffizienz aus Daten heraus evaluiert, und es wird gezeigt, dass die Methode in der Lage ist, die Effizienz ohne signifikante Verfälschung durch die Tag-Selektion zu bestimmen. In der zweiten datenbasierten Analyse wird eine neue Methode zur Abschätzung des W+Jets-Untergrundes in ATLAS eingeführt. Durch die Definition von signal- und untergrunddominierten Bereichen in Jet-Muliplizität und Pseudorapidität des Leptons wird der Anteil der W+Jets-Ereignisse aus der untergrunddominierten in die signaldominierte Region extrapoliert. Es wird gezeigt, dass die Methode, mit einer integrierten Luminosität von 100 pb^−1 bei sqrt(s) = 10 TeV, in der Lage ist den Untergrundbeitrag als Funktion der Jet-Muliplizität mit etwa 25% Genauigkeit im Großteil der signaldominierten Region zu bestimmen. Diese Arbeit umfaßt zudem eine Studie zum thermischen Verhalten und der erwarteten thermischen Leistung des Pixel-Detektors in ATLAS. Alle Messungen, durchgeführt während der Inbetriebnahme des Systems in 2008/09, zeigen Ergebnisse innerhalb der Spezifikationen beziehungweise deuten auf deren Einhaltung auch nach mehreren Betriebsjahren unter LHC-Bedingungen hin.The physics of the top quark is one of the key components in the physics programme of the ATLAS experiment at the Large Hadron Collider at CERN. In this thesis, general studies of the jet trigger performance for top quark events using fully simulated Monte Carlo samples are presented and two data-driven techniques to estimate the multi-jet trigger efficiency and the W+Jets background in top pair events are introduced to the ATLAS experiment. In a tag-and-probe based method, using a simple and common event selection and a high transverse momentum lepton as tag object, the possibility to estimate the multijet trigger efficiency from data in ATLAS is investigated and it is shown that the method is capable of estimating the efficiency without introducing any significant bias by the given tag selection. In the second data-driven analysis a new method to estimate the W+Jets background in a top-pair event selection is introduced to ATLAS. By defining signal and background dominated regions by means of the jet multiplicity and the pseudo-rapidity distribution of the lepton in the event, the W+Jets contribution is extrapolated from the background dominated into the signal dominated region. The method is found to estimate the given background contribution as a function of the jet multiplicity with an accuracy of about 25% for most of the top dominated region with an integrated luminosity of above 100 pb^−1 at sqrt(s) = 10 TeV. This thesis also covers a study summarising the thermal behaviour and expected performance of the Pixel Detector of ATLAS. All measurements performed during the commissioning phase of 2008/09 yield results within the specification of the system and the performance is expected to stay within those even after several years of running under LHC conditions.
30
Tanwar, Rajendra. "Guidelines for the preparation of thematic maps for the demographic atlas for the Brisbane City Council : 1991 census." Thesis, Queensland University of Technology, 1995.
Find full text
31
Shaikh, Nabila. "Energy Calibration of the Tile L1Calo and Data Driven Estimation of Non-prompt $e$, $\mu$ and $\tau$ Background Using Data From the ATLAS Detector." Licentiate thesis, Stockholms universitet, Fysikum, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-156377.
Full text
32
Ekelin, Svea, and Louise Hagesjö. "Making ATLAS Data from CERN Accessible to the General Public : The Development and Evaluation of a Learning Resource in Experimental Particle Physics." Thesis, KTH, Skolan för teknikvetenskaplig kommunikation och lärande (ECE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-211261.
Full textAbstract:
In 2016, the ATLAS experiment at CERN released data from 100 trillion proton-proton collisions to the general public. In connection to this release the ATLAS Outreach group has developed several tools for visualizing and analyzing the data, one of which is a Histogram analyzer. The focus of this project is to bridge the gap between the general public's knowledge in physics and what is needed to use this Histogram analyzer. The project consists of both the development and an evaluation of a learning resource that explains experimental particle physics for a general public audience. The learning resource is a website making use of analogies and two perspectives on learning: Variation Theory and Cognitive Load Theory. The evaluation of the website was done using a survey with 10 respondents and it focused on whether analogies and the perspectives on learning helped their understanding. In general the respondents found the analogies to be helpful for their learning, and to some degree they found the explanations based on Variation Theory to be helpful. The implementations of Cognitive Load Theory were considered to be helpful by the respondents who noticed them, but the majority did not, implying that improvements of the design are needed. The results indicate that analogies and the two perspectives on learning can be helpful for explaining experimental particle physics, but there might be other learning theories more suitable for this purpose.ATLAS-experimentet på CERN släppte år 2016 data från 100 biljoner proton-kollisioner fritt till allmänheten. I anslutning till detta har ATLAS Outreach-grupp utvecklat ett flertal verktyg för att visualisera och analysera datan, varav en är en analys med hjälp av histogram. Fokus för detta projekt är att överbrygga klyftan mellan allmänhetens kunskaper i fysik och vad som behövs for att kunna använda Histogram-analysverktyget. Projektet består både av utvecklandet och utvärderingen av ett läromedel som förklarar experimentell partikelfysik med målgruppen allmänheten. Läromedlet är en webbsida som använder sig av analogier och två perspektiv på lärande, Variationsteori och Kognitiv Belastningsteori. Utvärderingen av webbsidan gjordes med en enkät med tio respondenter, med fokus på huruvida analogier och perspektiven på lärande hjälpte deras förståelse. I allmänhet fann respondenterna analogierna hjälpsamma för deras lärande, och de fann Variationsteori hjälpsamt i viss utsträckning. Implementeringarna av Kognitiv Belastningsteori ansågs vara hjälpsamma av de respondenter som lade märke till dem, men majoriteten gjorde inte det, vilket tyder på att förbättringar av implementeringen krävs. Resultaten indikerar att analogier och de två perspektiven på lärande kan vara hjälpsamma för att förklara experimentell partikelfysik, men det kan finnas andra lärandeteorier som uppfyller syftet bättre.
33
Prichard, Paul Michael. "An investigation into the discovery potential for SUperSYmmetry at the LHC with early data from the ATLAS detector." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533931.
Full text
34
Rzehorz, Gerhard Ferdinand [Verfasser], Arnulf [Akademischer Betreuer] Quadt, Arnulf [Gutachter] Quadt, and Ramin [Gutachter] Yahyapour. "Data intensive ATLAS workflows in the Cloud / Gerhard Ferdinand Rzehorz ; Gutachter: Arnulf Quadt, Ramin Yahyapour ; Betreuer: Arnulf Quadt." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1160753555/34.
Full text
35
De, Luca Silvia. "Search for scalar and vector doubly charged bosons with Run2 data collected by the ATLAS experiment at LHC." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23285/.
Full textAbstract:
Il lavoro riportato in questa tesi si svolge nell’ambito delle teorie oltre il Modello Standard e riguarda la ricerca di bosoni scalari e vettoriali doppiamente carichi predetti nel Bilepton Model e nel Left-Right Symmetric Model (LRSM). Lo studio impiega i dati delle collisioni protone-protone raccolti dal rivelatore ATLAS durante il Run 2 del Large Hadron Collider a un’energia del centro di massa di 13 TeV, corrispondente a 139 fb−1 di luminosità integrata. L’analisi condotta sfrutta il canale multileptonico pp → H±±H∓∓(∆±±∆∓∓,Y±±Y∓∓) → `±`±`′∓`′∓ caratterizzato da uno stato finale formato da leptoni leggeri (`,`′=e,μ), di alta energia, isolati e prodotti direttamente dai bosoni provenienti dal vertice primario. Lo scopo è quello di estendere una precedente analisi includendo per la prima volta la presenza di bosoni vettoriali doppiamente carichi. Non osservando un eccesso rispetto alle predizioni del Modello Standard, è statocalcolato un limite di esclusione al 95% di CL per le masse dei bosoni interessati.
36
Wollrath, Julian [Verfasser], Christian [Akademischer Betreuer] Weiser, and Karl [Akademischer Betreuer] Jakobs. "Search for supersymmetry with top-squarks and ATLAS data at a centre-of-mass energy of 13 TeV." Freiburg : Universität, 2021. http://d-nb.info/1234910853/34.
Full text
37
Jeuthe, Julius. "Automatic Tissue Segmentation of Volumetric CT Data of the Pelvic Region." Thesis, Linköpings universitet, Medicinsk informatik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-133153.
Full textAbstract:
Automatic segmentation of human organs allows more accurate calculation of organ doses in radiationtreatment planning, as it adds prior information about the material composition of imaged tissues. For instance, the separation of tissues into bone, adipose tissue and remaining soft tissues allows to use tabulated material compositions of those tissues. This approximation is not perfect because of variability of tissue composition among patients, but is still better than no approximation at all. Another use for automated tissue segmentationis in model based iterative reconstruction algorithms. An example of such an algorithm is DIRA, which is developed at the Medical Radiation Physics and the Center for Medical Imaging Science and Visualization(CMIV) at Linköpings University. DIRA uses dual-energy computed tomography (DECT) data to decompose patient tissues into two or three base components. So far DIRA has used the MK2014 algorithm which segments human pelvis into bones, adipose tissue, gluteus maximus muscles and the prostate. One problem was that MK2014 was limited to 2D and it was not very robust. Aim: The aim of this thesis work was to extend the MK2014 to 3D as well as to improve it. The task was structured to the following activities: selection of suitable segmentation algorithms, evaluation of their results and combining of those to an automated segmentation algorithm. Of special interest was image registration usingthe Morphon. Methods: Several different algorithms were tested. For instance: Otsu's method followed by threshold segmentation; histogram matching followed by threshold segmentation, region growing and hole-filling; affine phase-based registration and the Morphon. The best-performing algorithms were combined into the newly developed JJ2016. Results: For the segmentation of adipose tissue and the bones in the eight investigated data sets, the JJ2016 algorithm gave better results than the MK2014. The better results of the JJ2016 were achieved by: (i) a new segmentation algorithm for adipose tissue which was not affected by the amount of air surrounding the patient and segmented smaller regions of adipose tissue and (ii) a new filling algorithm for connecting segments of compact bone. The JJ2016 algorithm also estimates a likely position for the prostate and the rectum by combining linear and non-linear phase-based registration for atlas based segmentation. The estimated position (center point) was in most cases close to the true position of the organs. Several deficiencies of the MK2014 algorithm were removed but the improved version (MK2014v2) did not perform as well as the JJ2016. Conclusions: JJ2016 performed well for all data sets. The JJ2016 algorithm is usable for the intended application, but is (without further improvements) too slow for interactive usage. Additionally, a validation of the algorithm for clinical use should be performed on a larger number of data sets, covering the variability of patients in shape and size.
38
Renaud, Adrien. "Recherche de gluons scalaires avec le détecteur ATLAS auprès du LHC." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00934510.
Full textAbstract:
Cette thèse décrit la recherche de nouvelles particules scalaires octets de couleur dans les données de l'expérience ATLAS auprès du Grand Collisionneur de Hadrons (LHC). Pour une large gamme de masse, la désintégration de ces scalaires en deux partons du MS domine. Cela motive la recherche de ces nouveaux scalaires dans des états finaux multijet, où ils se signaleraient comme des résonances dijet. Comme les nouveaux scalaires sont produits par paires, un état final contenant au moins quatre jets est utilisé comme environnement de recherche. Une méthode est développée pour extraire une possible résonance multijet scalaire du grand fond QCD et est utilisée pour chercher de tels scalaires dans les données de l'expérience ATLAS collectées en 2010 et 2011. Les données sont en accord avec l'estimation du fond et des limites sont posées sur la section efficace de production des scalaires en fonction de leur masse. En interprétant ces limites dans des modèles de supersymétrie, le gluon scalaire du MRSSM et du modèle hybride N=1/N=2 est exclu à 95 % CL entre 100 et 287 GeV. Les limites sont aussi interprétées dans un modèle de symétrie de jauge à la QCD, où le sgluon est remplacé par l'hyperpion qui est exclu dans une gamme de masse légèrement plus restreinte de part sa section efficace plus faible.
39
Gregory, Richard Cedric Thomas Art College of Fine Arts UNSW. "A graphic investigation of the atlas as a narrative format for the visual communication of cultural and social data." Awarded by:University of New South Wales. Art, 2009. http://handle.unsw.edu.au/1959.4/43798.
Full textAbstract:
Maps and atlases are traditionally convenient documents for representing the surface of the earth. They provide an impression of spatial relationships and facilitate an appreciation of geographical and environmental characteristics. They are essential tools for creating an awareness of the world beyond the limits of our experience. Maps can also inform readers on the flow of cultural or economic influences, because they show localities in relation to their neighbours. Furthermore, they capture the reader's imagination by provoking the desire for adventure and exploration. Occasionally maps are also censored because they are an efficient means of indicating strategic features. This project concerns the historical and contemporary examples of communicating information visually by analysing a selection of conventional literary and visual sources, which informs the research. It includes graphic forms that present abundant data, for example, atlases and texts on the architectural history of Central Asia, Tibet, China and Japan. The studio works will examine illustration, draughtsmanship, rendering, and textual/visual imagery. The outcome will be an illustrated atlas of traditional architecture in the earthquake zones of Central Asia (Xinjiang), Tibet, China, Japan and related areas. The graphic format is used as a narrative for the communication of environmental, cultural and architectural data of the region. The atlas is also intended to present the subject in a holistic form in relation to environmental influences on the structures and materiality of buildings, and the broader field of history.
40
Dugdale, Stephen John. "GIS-based modelling of the distribution of farmland birds in England and Wales using atlas data and functional guilds." Thesis, University of East Anglia, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539337.
Full text
41
Young, Christopher. "Searches with the ATLAS detector for new coloured particles in the Jets + Missing Energy channel in early LHC data." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:95c62feb-5e3c-47cb-889b-c3485cb95ca0.
Full textAbstract:
The switching on of the Large Hadron Collider (LHC) in March 2010 and its successful operation thereafter has opened doors in the search for new physics beyond the Standard Model. Supersymmetry (SUSY) is one of the leading theories that extends the Standard Model of particle physics. A search for new SUSY particles is presented requiring large numbers of hadronic jets and missing transverse momentum. Novel background estimation techniques were developed specifically for this final state, allowing the control of the backgrounds where the missing transverse momentum is dominated by jet miss-measurement. Other backgrounds are estimated from Monte-Carlo simulations validated and normalised in dedicated control regions. No significant excess was observed in the search. Model independent upper limits on the number of signal events passing the selection are given and the results are also interpreted in two planes of the parameter space. This is the most recent and sensitive incarnation of several searches developed by the author in this channel.
42
Little, Francesca. "The smooth is better than the rough : an exploitation of reporting rate information in Southern Africa bird atlas data." Doctoral thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/8592.
Full textAbstract:
Includes bibliographical references.The Southern African Bird Atlas Project (Harrison at el. 1997a, b) and the Mozambique Bird Atlas Project (Parker 1999) generated data on reporting rates for birds that takes into account the likelihood of species detection in a given area. Our main objective in this thesis is to explore methods for analysing and summarising reporting rate data. The observed reporting rate data are subject to bias due to differential sampling effort and observer errors. We use a logistic regression model suitable for binomial type data to replace the observed reporting rates with smoothed probabilities of detection. To base our prediction on data from the surrounding neighbourhood, we choose as explanatory variables the north-south and west-east coordinates relative to the target grid cell for which the prediction is being made. We explore some variants of our general smoothing approach that relates to the presentation of the smoothed distributions. The smoothed distributions of detection probabilities are presented as multicoloured maps. We consider two alternative ways of subdividing the range of detection probabilities into sub-intervals. One approach is species-specific, while the other imposes an absolute subdivision on all species distributions. For species with highly fragmented distributions, we introduce the possibility of using a weighted average between observed reporting rates and smoothed detection probabilities as the final value to be plotted. The weights are based on the extent of coverage and the underlying degree of fragmentation. The identification of patterns of distributions for species is an important part of biogeography and plays a major role in the identification of areas where conservation efforts should be targeted. Interest centres around identifying areas of species richness, centres for narrow eudemism and zones of transition in species composition. We explore the benefits of using a range of detection probabilities in comparison to the use of presence-absence data to identify areas rich in species and rich in narrow-endemic species. We transform existing measures for species richness and species endemism by replacing presence-absence data with detection probability deciles that reflect the relative likelihood of detecting a species in a given grid cell. The resulting measures give more weight to the areas where species have the core of their distributions and down-weight the peripheral edges of the species distributions, where detection probabilities may be too small to guarantee continued survival. The use of a mathematical model to generate smoothed distributions of detection probabilities enables us to calculate gradients for the detection probability surfaces for species. We can define the concept of individual species gradients that reflect the relative degree of change among detection probabilities within the overall range of occurrence for the species. We combine the gradients for all species in several different ways. Large values for the overall sums of the gradients indicate areas of large fluctuation in species composition. On the other hand, small values for the overall gradient sums indicate areas of relative stability. We also sum the gradients in one of 16 directions. These directional gradient sums distinguish between areas where the changes in species detection probability distributions occur in isolated directions, thus indicating ecological transition zones, and areas of random fluctuation, indicative of species fragmentation. In this thesis we do not derive new statistical methods. We adapt existing techniques to deal with the abundance component of the data generated by the bird atlas projects. We show how the measures based on reporting rate data, rather than presence-absence data, add substantial insight into patterns of distribution of bird species in southern Africa.
43
Erni, Birgit. "Analysis of distribution maps from bird atlas data : dissimilarities between species, continuity within ranges and smoothing of distribution maps." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/14721.
Full textAbstract:
Includes bibliographical references.A dissimilarity coefficient for estimating the dissimilarity between two bird atlas distributions is developed. This coefficient is based on the Euclidean distance concept. The atlas distributions are compared over all quarter degree grid cells. Existing coefficients are not suitable for the comparison of distributions with different total areas and species with different mean reporting rates. In each grid cell the reliability of the reporting rates depends on the number of checklists collected for the grid cell. Weights are used to solve this problem. To solve the problem of different levels of abundance and conspicuousness of species, the reporting rates are sorted into percentiles, using five or 10 categories for the strictly positive reporting rates. Each grid cell is weighted by a function of the number of checklists collected for the grid cell. The coefficient is scaled by the maximum possible sum of the differences which would occur if there is no overlap between the two distributions, so that the dissimilarity coefficient lies between zero (a perfect match) and one (no overlap). A variety of these coefficients are investigated and compared. The continuity of observed reporting rates in a spatial cellular map is an indication of spatial autocorrelation present, especially between observations which are in close vicinity. We are particularly interested in measuring and comparing the continuity of the reporting rates in the bird distributions from The Atlas of Southern African Birds. The variogram, developed in geostatistics, estimates this spatial autocorrelation. The classical variogram estimator, however, is dependent on the scale of measurement and assumes that the data are intrinsically stationary. The bird atlas distribution maps contain trend and the variance of each observation (reporting rate) is a function of the number of checklists collected for the grid cell and the underlying probability of encountering the species in the grid cell. The approach of removing this binomial measurement error from the variogram developed by McNeill (1991) is investigated but not found satisfactory. A weighted variogram, where each squared difference is weighted by a function of the smaller number of checklists, is developed. To make the variogram values comparable between species a function of the mean reporting rates is used to scale the variogram. We were particularly interested in the first variogram value of each species distribution, 2y(1). The bird distribution maps in The Atlas of Southern African Birds show the raw observed reporting rates. Each of these reporting rates is a random variable dependent on sampling error due to binomial variation based on the number of checklists collected for the grid cell and on the underlying probability of encountering the species. The distribution maps show this measurement error. It is believed that a smoothed version of the bird distribution maps will to some extent improve the statement these observed distributions are aiming to make. Single-step regression methods are investigated for a fast approach to this problem. These cause problems because of frequent 'zero' observed reporting rates and because they smooth the maps too heavily. Generalized Linear Models are investigated and this iterative procedure is applied to model the reporting rates with a binomial distribution on square blocks of nine grid cells where a value for the central cell is 'predicted' in each regression. This approach is especially suited to accommodate the binomial distribution characteristics and is found to smooth the bird atlas distributions well. Because only a local window is taken for each regression, the spatial autocorrelation is adequately included in the spatial explanatory variables.
44
Allen, Benjamin. "Search for New Phenomena in Dijet Events Using 13 TeV Proton-Proton Collision Data Collected With the ATLAS Detector." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23801.
Full textAbstract:
Dijet events are studied in the proton--proton collision dataset recorded at $\sqrt{s}=$13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated luminosities of 37 fb$^{-1}$. Invariant mass distributions are compared to background predictions and no significant deviation is observed. A new method for fitting the background component of the invariant mass distribution is employed. The dataset is used to set upper limits at a 95\% confidence level on a range of new physics scenarios. Excited quarks with masses below 6.0 TeV are excluded, and limits are set on quantum black holes, heavy W' bosons, W* bosons, and a range of masses and couplings in a Z' dark matter mediator model. These results represent a substantial improvement over those obtained previously with lower integrated luminosity.
45
Belias, Anastasios. "Electron/jet discrimination and b-jet tagging at the second level trigger of ATLAS." Thesis, Royal Holloway, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326090.
Full text
46
Friedrich, Conrad. "Search for single top-quark production via flavour-changing neutral currents in strong interactions using s = 8 TeV ATLAS data." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2015. http://dx.doi.org/10.18452/17348.
Full textAbstract:
In dieser Dissertation werden Resultate einer Suche nach der Produktion von Einzel-Top-Quarks über flavour-verletzende neutrale Ströme (FCNCs) in starken Welchselwirkungen vorgestellt. Hierfür werden Daten aus Proton-Proton-Kollisionen am Large Hadron Collider bei einer Schwerpunktsenergie von 8TeV verwendet. Die Daten wurden mit dem ATLAS-Experiment im Jahr 2012 aufgenommen und entsprechen einer integrierten Luminosität von 14.1 fb−1. In der Analyse werden FCNC-Ereignisse selektiert, in denen ein leichtes Quark (u oder c) mit einem Gluon wechselwirkt, und ein einzelnes Top-Quark und potentiell ein weiterer einzelner Jet produziert wird. Mittels der Forderung nach genau einem Myon oder Elektron, großer fehlender Transversalenergie und exakt einem Bottom-Quark-Jet und eventuellem zusätzlichen Jet im Endzustand werden Kandidaten der gesuchten Ereignisse im leptonischen Zerfallskanal des Top-Quarks selektiert. Zur Unterscheidung zwischen Signal- und Untergrundereignissen werden multivariate Methoden herangezogen. Künstliche neuronale Netze werden verwendet, um diverse kinematische Variablen zu einem einzelnen Klassifikator zu kombinieren. Um die potentielle Produktion von Top-Quarks über FCNCs zu quantifizieren, werden die Ausgaben der neuronalen Netze einer Bayes''schen statistischen Analyse unterzogen. Da kein Überschuss an Signalereignissen festgestellt werden kann und die Ergebnisse den Erwartungen der theoretischen Vorhersagen entsprechen, werden neue obere Schranken auf den FCNC-Produktionswirkungsquerschnitt von Einzel-Top-Quarks ermittelt. Aus diesen werden unter Verwendung von modell-unabhängigen theoretischen Berechnungen neue obere Schranken auf die Kopplungskonstanten sowie auf die entsprechenden Verzweigungsverhältnisse ermittelt.This thesis presents results of a search for single top-quark production via flavour-changing neutral currents (FCNCs) in strong interactions using data recorded with the ATLAS experiment at the Large Hadron Collider in 2012. A dataset from proton-proton collisions at a centre-of-mass energy of 8TeV and corresponding to an integrated luminosity of 14.1 fb−1 is used. It is searched for FCNC events in which a light quark (u or c) interacts with a gluon to produce a single top quark, either with or without the associated production of another light quark or gluon. Candidate events of leptonically decaying top-quarks are selected by requiring a single electron or muon, a substantial amount of missing transverse energy, and exactly one or two jets of which exactly one has to fulfil a b-tagging criterion. Multivariate techniques are employed in order to distinguish between signal- and background-like events by making use of artificial neural networks that combine multiple kinematic variables into a single classifier output. A Bayesian statistical analysis is performed on the classifier outputs in order to quantify potential signs of FCNC single top-quark production. No excess in signal events is observed and the results are in agreement with the theory predictions. Consequently a new upper limit is set on the FCNC single top-quark production cross-section multiplied by the t->Wb branching fraction. Using theory calculations within a model-independent effective theory framework, this limit is converted into upper limits on the coupling constants of the FCNC interactions as well as into respective upper limits on the branching fractions.
47
Aad, G., Richard Brenner, Claus P. Buszello, Tord Ekelöf, Mattias Ellert, Arnaud Ferrari, and L. Zwalinski. "Search for a heavy neutral particle decaying into an electron and a muon using 1 fb(-1) of ATLAS data." Uppsala universitet, Högenergifysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-171766.
Full textAbstract:
A search is presented for a high mass neutral particle that decays directly to the e(+/-) mu(-/+) final state. The data sample was recorded by the ATLAS detector in root s = 7 TeV pp collisions at the LHC from March to June 2011 and corresponds to an integrated luminosity of 1.07 fb(-1). The data are found to be consistent with the Standard Model background. The high e(+/-) mu(-/+) mass region is used to set 95% confidence level upper limits on the production of two possible new physics processes: tau sneutrinos in an R-parity violating supersymmetric model and Z'-like vector bosons in a lepton flavor violating model.ATLAS Collaboration, for complete list of authors see http://dx.doi.org/10.1140/epjc/s10052-011-1809-9
48
Hönig, Georg Friedrich [Verfasser], and Dorothee [Akademischer Betreuer] Schaile. "Search for a scalar dimuon resonance with LHC Run2 data from the ATLAS detector / Georg Friedrich Hönig ; Betreuer: Dorothee Schaile." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1135136351/34.
Full text
49
Stärz, Steffen. "Energy Reconstruction and high-speed Data Transmission with FPGAs for the Upgrade of the ATLAS Liquid Argon Calorimeter at LHC." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-172213.
Full textAbstract:
The Liquid Argon calorimeter of the ATLAS detector at CERN near Geneva is equipped with improved readout and trigger electronics for the operation at higher luminosity LHC in the frame of several upgrades (Phase-0, I, and II). Special attention is given to an early digitisation of detector raw data and their following digital data transmission and processing via FPGAs already for the Level-1 trigger. The upgrades additionally foresee to provide higher spatial granularity information for the Level-1 trigger in order to improve its performance for low momentum single particles at increased collision rates. The first part of this dissertation contains the development and implementation of a modular detector simulation framework, AREUS, which allows to analyse different filter algorithms for the energy reconstruction as well as their performance with respect to the expected digitised detector raw data. In this detector simulation framework the detailed algorithmic functionality of the FPGAs has been taken into account. Various filter algorithms, especially the Optimal Filter and a Wiener Filter with Forward Correction, are discussed with regard to their performance in energy reconstruction of the future Liquid Argon calorimeter trigger system. In the second part of this thesis, the high-speed data transfer for the acquisition of the trigger data is being developed. For this purpose, a generic 10 Gigabit Ethernet UDP stack is designed in VHDL, that is currently applied in an ALTERA® Stratix-IV FPGA as part of the readout electronics of a demonstrator setup in the context of the Phase-0 Upgrade. After implementation in a prototype electronics board, data transfer from the detector front-end is realised. A successful test in the demonstrator setup installed in the ATLAS detector verifying the correct transmission of the Liquid Argon calorimeter trigger signals concludes this workDas Flüssig-Argon-Kalorimeter des ATLAS-Detektors am CERN bei Genf wird für den Betrieb am LHC mit erhöhter Luminosität im Rahmen mehrerer Upgrades (Phase-0, I und II) mit verbesserter Auslese- und Triggerelektronik ausgestattet. Ein besonderes Augenmerk liegt hierbei auf der frühzeitigen Digitalisierung der Detektorrohdaten und deren folgende digitale Übertragung sowie Verarbeitung mittels FPGAs bereits für den Level-1 Trigger. Die Upgrades sehen zusätzlich vor, dem Level-1 Trigger eine höhere Ortsauflösung bereitzustellen um seine Leistungsfähigkeit der Energierekonstruktion von niedrigenergetischen Teilchen bei erhöhter Kollisionsrate zu verbessern. Der erste Teil dieser Dissertation beinhaltet die Entwicklung und Umsetzung einer modularen Detektorsimulationsumgebung, AREUS, mit der verschiedene Filteralgorithmen zur Energierekonstruktion sowie deren Performanz in Abhängigkeit der erwarteten digitalisierten Detektorrohdaten analysiert werden können. Dabei wurde in der Simulationsumgebung die Funktionalität der Rechenarithmetik der später verwendeten FPGAs berücksichtigt. Verschiedener Filteralgorithmen, im Besonderen der Optimal Filter und ein Wiener Filter mit Korrekturglied, werden im Hinblick auf ihre Performanz der Energierekonstruktion für das zukünftige Triggersystem des Flüssig-Argon-Kalorimeters diskutiert. Der zweite Teil dieser Arbeit beschäftigt sich mit der Hochgeschwindigkeitsdatenübertragung zur Erfassung von Triggerdaten. Zu diesem Zweck wird ein generischer 10 Gigabit Ethernet UDP Stack in VHDL entworfen, der als Teil der Ausleseelektronik eines Demonstrator-Testaufbaus im Rahmen des Phase-0 Upgrades in einem ALTERA® Stratix-IV FPGA aktuell zum Einsatz kommt. Nach Implementierung in einem Prototypen einer Auslesekarte konnte ein Transfer von Detektordaten realisiert werden. Eine Überprüfung am Demonstrator-Testaufbau, welcher im ATLAS Detektor installiert ist, schließt diese Dissertation ab. Sie hat eine korrekte Übertragung von Triggersignalen des Flüssig-Argon-Kalorimeters erfolgreich bestätitgt
50
Hidvégi, Attila. "FPGA-based Instrumentation for Advanced Physics Experiments." Doctoral thesis, Stockholms universitet, Fysikum, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-64506.
Full textAbstract:
Modern physical experiments often demand advanced instrumentation based on advances in technology. This work describes four instrumentation physics projects that are based on modern, high-capacity Field-Programmable Gate Arrays, making use of their versatility, programmability, high bandwidth communication interfaces and signal processing capabilities. In the first project, a jet-finding algorithm for the ATLAS detector at the LHC experiment at CERN was developed and implemented, and different verification methods were created to validate the functionality and reliability. The experiment uses a three level trigger system, where the first level uses custom FPGA-based hardware for analysis of collision events in real-time. The second project was an advanced timing and triggering distribution system for the new European X-Ray Free Electron Laser (XFEL) facility at DESY in Hamburg. XFEL will enable scientists to study nano structures on the atomic scale. Its laser pulses will have the strongest peak power in the world with extremely short duration and a high repetition rate, which will even allow filming of chemical reactions. The timing system uses modern FPGAs to distribute high-speed signals over optical fibers and to deliver clocks and triggers with high accuracy. The third project was a new data acquisition board based on high-speed ADCs combined with high-performance FPGAs, to process data from segmented Ge-detectors in real-time. The aim was to improve system performance by greatly oversampling and filtering the analog signals to achieve greater effective resolution. Finally, an innovative solution was developed to replace an aging system used at CERN and Stockholm University to test vital electronics in the Tile Calorimeters of the ATLAS detector system. The new system is entirely based on a commercial FPGA development board, where all necessary custom communication protocols were implemented in firmware to emulate obsolete hardware.Inom området instrumenteringsfysik bedrivs forskning och utveckling av avancerade instrument, som används inom moderna fysikexperiment. Denna avhandling beskriver fyra projekt där programmerbara kretsar (FPGA) har nyckelfunktioner för att lösa krävande instrumenteringsuppgifter. Den första projektet beskriver utveckling och implementering av en algoritm för detektering av partikelskurar efter partikelkollisioner i LHC-experimentets ATLAS-detektor. Experimentet genererar 40 miljoner händelser per sekund, som måste analyseras i real-tid med hjälp av snabba parallella algoritmer. Resultatet avgör vilka händelser som är tillräckligt intressanta för fortsatt noggrannare analys. Den andra projektet beskriver utvecklingen av ett system som distribuerar klock- och trigger-signaler över ett 3 kilometers experimentområde med extrem precision, i den nya röntgenlaseracceleratorn XFEL vid DESY i Hamburg. Vid XFEL kommer man utforska nanostrukturer och till och med filma molekylers kemiska reaktioner. I den tredje projektet beskrivs utvecklingen av ett höghastighets datainsamlingssystem, för segmenterade Ge-detektorer. Genom att översampla signalen med hög hastighet kan man uppnå en bättre noggrannhet i mätningen än vad AD-omvandlarens egna upplösning medger. Detta leder i sin tur till förbättrade systemprestanda. Slutligen beskrivs en innovativ lösning till ett test system för den elektronik, som Stockholms universitet har levererat till ATLAS detektorn. Det nya systemet ersätter det föregående testsystemet, som är baserad på föråldrade inte längre tillgängliga komponenter. Det nya systemet är dessutom också billigare eftersom det är baserat på ett standard FPGA utvecklingskort.
ATLAS experiment of the Large Hadron Collider experiment
European X-ray Free Electron Laser