Supersymmetry is a promising candidate theory that could solve the hierarchy problem and explain the dark matter density in the Universe. The ATLAS experiment at the Large Hadron Collider is sensitive to a variety of such supersymmetric models. This thesis reports on a search for pair production of the supersymmetric scalar partners of bottom and top quarks in 20.1 fb⁻¹ of pp collisions at a centre-of-mass energy of 8 TeV using the ATLAS experiment. The study focuses on final states with large missing transverse momentum, no electrons or muons and two jets identified as originating from a b-quark. This final state can be produced in a R-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom decays exclusively to a bottom quark and a neutralino and the scalar top decays to a bottom quark and a chargino, with a small mass difference with the neutralino. As no signal is observed above the Standard Model expectation, competitive exclusion limits are set on scalar bottom and top production, surpassing previously existing limits. Sbottom masses up to 640 GeV are excluded at 95% CLs for neutralino masses of up to 150 GeV. Differences in mass between ^~<sub style='position: relative; left: -.7em;'>b</sub>₁ and ^~<sub style='position: relative; left: -.7em;'>X</sub>⁰<sub style='position: relative; left: -.5em;'>1</sub> larger than 50 GeV are excluded up to sbottom masses of 300 GeV. In the case of stop pair production and decay ^~<sub style='position: relative; left: -.7em;'>t</sub>₁ → b + ^~<sub style='position: relative; left: -.7em;'>X</sub>^±<sub style='position: relative; left: -.5em;'>1</sub> and ^~<sub style='position: relative; left: -.7em;'>X</sub>^±<sub style='position: relative; left: -.5em;'>1</sub> → ^~<sub style='position: relative; left: -.7em;'>X</sub>⁰<sub style='position: relative; left: -.5em;'>1</sub> + W* with mass differences &triangle;m = m_{^~<sub style='position: relative; left: -.7em;'>X}^±<sub style='position: relative; left: -.5em;'>1</sub></sub> − m_{^~<sub style='position: relative; left: -.7em;'>X}⁰<sub style='position: relative; left: -.5em;'>1</sub></sub> = 5 GeV (20 GeV), stop masses up to 580 GeV (440 GeV) are excluded for m_{^~<sub style='position: relative; left: -.7em;'>X}⁰<sub style='position: relative; left: -.5em;'>1</sub></sub> = 100 GeV. Neutralino masses up to 280 GeV (230 GeV) are excluded for m_{^~<sub style='position: relative; left: -.7em;'>t}₁</sub> = 420 GeV for &triangle;m = 5 GeV (20 GeV). In an extension of this analysis, sbottom quarks cascade-decaying to at least a Higgs boson are searched for in final states with large missing transverse momentum, at least 3 b-tagged jets and no electrons or muons, using neural network discriminants.

The search for a Higgs boson decaying to a b¯b pair is one of the key analyses ongoing at the ATLAS experiment. Despite being the largest branching ratio decay for a Standard Model Higgs boson, a large dataset is necessary to perform this analysis because of the very large backgrounds affecting the measurement. To discriminate the electroweak H → b¯b signal from the large QCD backgrounds, the associated production of the Higgs with a W or a Z boson decaying leptonically is used. Different techniques have been proposed to enhance the signal over background ratio in the VH(b¯b) channel, from dedicated kinematic cuts, to a single large radius jet to identify the two collimated b’s in the Higgs high transverse momentum regime, to multivariate techniques. The high-pT approach, using a large radius jet to identify the b’s coming from the Higgs decay, has been tested against an analysis based on kinematic cuts for a dataset of 4.7 fb−1 luminosity at √s = 7 TeV, and compatible results were found for the same transverse momentum range. Using a kinematic cut based approach the VH(b¯b) signal search has been performed for the full LHC Run 1 dataset: 4.7 fb−1 at √s = 7 TeV and 20.7 fb−1 at √s = 8 TeV. Several backgrounds to this analysis, such as Wb¯b have not been measured in data yet, and an accurate study of the theoretical description has been performed, comparing the predictions of various Monte Carlo generators at different orders. The complexity of the analysis requires a profile likelihood fit with several categories and almost 200 parameters, taking into account all the systematics coming from experimental or modelling limitations, to extract the result. To validate the fit model, a test of the ability to extract the signal is performed on the resonant V Z(b¯b) background. A 4.8σ excess compatible with the Standard Model rate expectation has been measured, with a best fit value μVZ = 0.93+0.22−0.21. The full LHC Run1 dataset result for the VH(b¯b) process is a limit of (1.3)1.4 x SM (expected) observed, with a best fit value of 0.2±0.5(stat)±0.4(sys) for a Higgs boson of 125 GeV mass.

Atlas Copco Craelius är en del av Atlas Copcos division Geotechnical Drilling and Exploration inom affärsområdet anläggnings- och gruvteknik. Atlas Copco Craelius som är beläget i Märsta utanför Stockholm utvecklar, tillverkar och marknadsför utrustning för undersöksborrning, grundläggning och markförstärkning. Detta examensarbete syftar till att identifiera möjliga förbättringsområden i materialhanteringen och effektivisering av materialflöden. Fokus för examensarbetet har riktats mot vilken strategi och principer som används för lagerhållningen och utformning av lagerlayouten. Examensarbetet är också en del av Atlas Copco Craelius kontinuerliga verksamhet om att ständigt utveckla och förbättra verksamheten och arbetsmetoder. I examensarbetet har en organisationsjämförelse gjorts mot både Scania och Öhlins för att nyansera infallsvinklarna och bidra med ett annat perspektiv på verksamheten. Slutligen har denna rapport författats innehållande förbättrings- och utvecklingsområden med förslag på hur materialhanteringen kan förbättras samt materialflöden effektiviseras, med reducerade ledtider och transporter samt förbättrad arbetsmiljö som positiva effekter.

Global illumination algorithms are used to render photorealistic images of 3D scenes taking into account both direct lighting from the light source and light reflected from other surfaces in the scene. Algorithms based on computing radiosity were among the first to be used to calculate indirect lighting, although they make assumptions that work only for diffusely reflecting surfaces. The classic radiosity approach divides a scene into multiple patches and generates a linear system of equations which, when solved, gives the values for the radiosity leaving each patch. This process can require extensive calculations and is therefore very slow. An alternative to solving a large system of equations is to use a Monte Carlo method of random sampling. In this approach, a large number of rays are shot from each patch into its surroundings and the irradiance values obtained from these rays are averaged to obtain a close approximation to the real value. <br /><br /> This thesis proposes the use of a Monte Carlo method to generate radiosity texture maps on graphics hardware. By storing the radiosity values in textures, they are immediately available for rendering, making this algorithm useful for interactive implementations. We have built a framework to run this algorithm and using current graphics cards (NV6800 or higher) it is possible to execute it almost interactively for simple scenes and within relatively low times for more complex scenes.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

The thesis Czech-Slovak lexical correspondences and differences in terms of their position in the standard language and dialects focuses on lexemes occurring equally in the areas of Czech and Slovak Republic (with a preference focus on border line of East Moravian and West Slovak dialects) and confrontation of their statuses in the national languages. The aim of the thesis is to track differences and concordances of Czech (Moravian) and Slovak dialect lexical parallels on a chosen sample of vocabulary from the perspective of their relation to the standard vocabulary of Czech and Slovak language. The opening chapter deals with language atlases and dictionaries used as sources for confrontation. This is followed by an image of Czech - Slovak language relations' development, question of border and evaluation of dialects from the perspective of belonging to Czech/Slovak dialects; and delimitation of assumed areas with the highest number of language concordances. The essence of the thesis are chosen dialectical lexemes obtained primarily from the Slovak Language Atlas (Atlas slovenského jazyka) and Czech Language Atlas (Český jazykový atlas), the assessment of extensity of area distribution of the researched lexemes and their comparison with codification dictionaries, Czech and Slovak. A separate...

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.

The Standard Model of Particle Physics describes the fundamental building blocks of matter and phenomena up to the highest particle interaction energies. The theory demands the existence of a scalar particle: the Higgs boson. The Higgs boson was discovered by the ATLAS and CMS collaborations at CERN using bosonic final states and is measured to have a mass of around 125 GeV. This particle is predicted to decay predominantly into pairs of b-quarks at this mass, but suffers from overwhelming backgrounds from the multijet production expected from QCD interactions. Therefore, H→bb- production in association with a leptonically decaying W or Z boson is considered, with Z → vv-, W → lv and Z → ll, where ` denotes electrons and muons. This thesis presents a search for the Higgs boson decaying into bb- pairs in association with a W or Z boson using the ATLAS detector at the Large Hadron Collider (LHC) at CERN. The analysis uses the full dataset recorded during pp collisions at the LHC in Run-1, corresponding to 4.7 fb-1 at √s = 7 TeV and 20.3 fb-1 at √s = 8 TeV. A multivariate technique and a kinematic cut-based approach have been used to maximize the signal over background ratio, where a particular emphasis on the latter approach is made in this thesis. Final state radiation and reconstruction effects may decrease the bb- resonance resolution significantly, while comparably decreasing the probability of observing the decay over the background. The b quark pairs from the Higgs boson are reconstructed as topological clusters formed to jets in the ATLAS calorimeter. Thus, the reconstruction and calibration of these jets are crucial for the final Higgs mass resolution and paramount for the search and for future precision measurements of V H, H→bb- production. This thesis presents the development and evaluation of advanced techniques to improve the invariant dijet mass reconstruction of the H→bb- candidate. Sequential jet calibrations, semileptonic corrections and pT corrections to account for the interplay between jet resolution/scale and the underlying signal pT spectrum obtained from Monte Carlo simulations have been studied. A major focus has been made on the development and evaluation of an event-level kinematic likelihood fitting framework to exploit the full kinematic potential of V H topologies within the detector uncertainties of the reconstructed final state signatures in order to improve the measurement of the b-tagged jet kinematics. The jet energy calibrations of the H→bb- signal candidates yield an overall improvement of the dijet invariant mass resolution of up to ~30%, and of the expected statistical significance of ~12%. The analysis procedure is validated using the resonant V Z(bb-) production in the same final states as for the Higgs boson search, and is observed, compatible with the Standard Model expectation, with a significance of 4.9 standard deviations and a signal strength of μ^V Z = 0:74+0:17 -0:16. For a Higgs boson mass of 125.36 GeV, the observed (expected) deviation from the background-only hypothesis is found with a significance of 1.4 (2.6) standard deviations and a signal strength is determined to be μ^V H = 0:52±0:32(stat.)±0:24(syst.).

This thesis describes a measurement of the Standard Model Higgs boson coupling to fermions in decays to two τ-leptons, a search for charged Higgs bosons in decays to a τ-lepton and a neutrino, as well as the reconstruction, identification and triggering of hadronically decaying τ-leptons. The data considered are collected by the ATLAS experiment at the Large Hadron Collider. The reconstruction and identification of hadronically decaying τ-leptons in the ATLAS experiment during Run 2 of the Large Hadron Collider are described, and the performance of the τ trigger is measured in events with top–antitop-quark pairs using data from 13 TeV proton–proton collisions, corresponding to an integrated luminosity of 3.2 fb-1, collected in 2015, and 11.5 fb-1, collected in 2016. Hadronically decaying τ-leptons are of importance to many physical processes involving Higgs bosons. The coupling of the Standard Model Higgs boson to fermions is measured in decays to two τ-leptons using 7 TeV data corresponding to an integrated luminosity of 4.5 fb-1, collected in 2011, and 8 TeV data corresponding to an integrated luminosity of 20.3 fb-1, collected in 2012. The signal strength is measured to be μ = 1.4, corresponding to an excess over the background-only model of 4.5σ. Charged Higgs bosons are searched for in decays to a τ-lepton and a neutrino, where the τ-lepton decays hadronically. 13 TeV data corresponding to an integrated luminosity of 14.7 fb-1, collected in 2015 and 2016, are used. No excess over the Standard Model background is observed, and the 95 % confidence-level exclusion limits on σ(pp → [b]tH+) × (H+ → τν) are set to 2.0 pb–8 fb in the range 200–2000 GeV.

This thesis presents searches for evidence for Weakly Interacting Massive Particles (WIMPs) and Extra Dimensions in proton-proton collisions recorded by the ATLAS experiment at the CERN Large Hadron Collider (LHC). The WIMP is one of the main candidates to constitute the particle content of Dark Matter. Extra Dimensions are introduced in several theories in order to explain the apparent weakness of gravity when compared to the other interactions in Nature. Theories with WIMPs as well as Extra Dimensions can manifest themselves at the LHC, with experimental signatures characterized by an energetic hadronic jet associated with large missing momentum. These signatures are known as monojet signatures, and are investigated in this thesis.  The first analysis is performed using L = 20.3 fb-1 of proton-proton collisions at √s = 8 TeV recorded in the ATLAS Run 1. The second analysis is performed using L = 3.2 fb-1 of proton-proton collisions at √s = 13 TeV recorded in the ATLAS Run 2. No significant excess over the expected background is found in either of the analyses. New exclusion limits are set at 95% confidence level on Dark Matter particle production. New limits are also set on graviton production in the so-called ADD scenario with Extra Dimensions.