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Cross-section measurements of the Higgs boson decaying into a pair of tau leptons with the ATLAS detector
Mlynáriková, Michaela ; Davídek, Tomáš (advisor) ; Hubáček, Zdeněk (referee) ; Šumbera, Michal (referee)
The ATLAS experiment is one of the two general-purpose detectors at the Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) in Switzerland. ATLAS is designed for precision mea- surements of particle properties, the search of the Higgs boson and new physics beyond the Standard Model. The experiment got worldwide atten- tion in 2012, when after the collaborative efforts with the CMS experiment the Higgs boson discovery was announced. After the discovery, the preci- sion measurements of its properties became one of the main objectives of the LHC physics programme, since a potential observation of deviations from the Standard Model predictions might lead to the discovery of new physics. In this thesis, the measurements of the Higgs boson production cross-sections in the H → ττ decay channel are presented. Based on the proton-proton collision data collected at the centre-of-mass energy of 13 TeV in years 2015 and 2016, the signal over the expected background from the other Standard Model processes is established with the observed significance of 4.4σ. Com- bined with the data collected at 7 and 8 TeV, the observed signal significance amounts to 6.4σ, which constitutes a single experiment observation of the H → ττ decays by ATLAS. All presented results are found to be consistent with...
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Response of the ATLAS Tile Calorimeter
Adámek, Tomáš ; Davídek, Tomáš (advisor) ; Faltová, Jana (referee)
TileCal is the Hadronic calorimeter covering the most central region of the ATLAS experiment which is one of the four major experiments at the Large Hadron Collider (LHC) at CERN. Main area of interest of this bachelor thesis is to examine the energy response and resolution of tested modules to electrons. Furthermore, the goal of this work is to make correction to the energy response with respect to the periodic structure of TileCal's cell.
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Response of the ATLAS Tile Calorimeter
Poláček, Stanislav ; Davídek, Tomáš (advisor) ; Novotný, Vladimír (referee)
Sandwich hadronic Tile Calorimeter is part of the ATLAS experiment at the Large Hadron Collider in European Organization for Nuclear Research CERN laboratory near Geneva in Switzerland. The goal of this thesis is to examine the response of parts of the Tile Calorimeter to the beam of electrons accelerated to energy of 100 GeV and the dependance of the electron signal on the beam impact point. 1
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Time calibration of the ATLAS Tile Calorimeter
Uhliarová, Lea ; Davídek, Tomáš (advisor) ; Slovák, Radim (referee)
The ATLAS is one of several particle experiments at the Large Hadron Col- lider at CERN. Millions of particles are colliding in it every second and it is one of two experiments which have proved the existence of the Higgs boson in 2012. The ATLAS experiment has two main goals. The search for new physics phenomena and precision measurement of the particle interactions. It consists of a complex system of detectors and read out electronics. The cal- ibration of the whole system is essential for getting correct results and mak- ing reasonable conclusions. This thesis is aimed to time calibration of Tile Calorimeter, which is one of calorimeters measuring energy of particles issued from the collision. Time monitoring and correction is performed primarily using laser pulses. In this thesis we described the used laser method which leads to the good time setting. 1
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Measurement of the top quark properties
Schovancová, Jaroslava ; Chudoba, Jiří (advisor) ; Davídek, Tomáš (referee) ; Filipčič, Andrej (referee)
Title: Measurement of the top quark properties Author: Mgr. Jaroslava Schovancová Department: Institute of Physics, Academy of Sciences of the Czech Re- public Supervisor: RNDr. Jiří Chudoba, Ph.D., Institute of Physics, Academy of Sciences of the Czech Republic Abstract: This Thesis presents the ATLAS experiment measurement of the top quark differential cross-section as a function of pT, mass and rapidity of the t¯t system. A sample of approx. 4.7 fb−1 of the 2011 pp collision data at the center-of-mass energy of 7 TeV was analyzed. The differential spectra shapes in the t¯t system are consistent with the Standard Model and reason- ably described by the event generators. Several activities in the scope of ATLAS Distributed Computing are pre- sented, particularly in the area of operations, monitoring, automation, and development of the PanDA Workload Management System. Such activities aim to improve efficiency and facilitate the use of distributed computing re- sources and therefore contribute in supporting the ATLAS Physics Program. Keywords: ATLAS, top quark, differential cross-section, missing transverse energy, ATLAS Distributed Computing
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Time calibration and resolution of the hadronic Tile Calorimeter
Krejčíková, Martina ; Davídek, Tomáš (advisor) ; Spousta, Martin (referee)
The thesis deals with Tilecal hadron calorimeter, which is part of the ATLAS detector at the LHC at CERN. Main area of interest is a time calibration of the detector, which is necessary to accurately determine the energy especially of jets produced as a result of precipitation collisions of protons. Based on obtained experimental data from 2011 thoroughly explored the relationships between the time of arrival of the particles into the cells of the detector and their energies, or the distance from the given objects. By describing the time calibration, one can correct originally obtained time constants. Description and resolution of time jumps in timing of channels are part of the thesis, corrections of identified examples are included. Powered by TCPDF (www.tcpdf.org)
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Studium kosmického záření o nejvyšších energiích
Novotný, Vladimír ; Nosek, Dalibor (advisor) ; Davídek, Tomáš (referee)
Research of the highest energy cosmic ray particles is in the middle of the interest of theoretical and experimental physics. Their energies are several orders of magnitude higher than energies accessible at present accelerators. In this work, the reconstruction techniques of extensive air showers measured at the Pierre Auger Observatory are studied. For this purpose, extensive air showers are modelled in the simulation tool CORSIKA. Data collected at the Pierre Auger Observatory together with simulations are used to calculate resolutions of reconstruction methods. The Multiple--eye reconstruction is the main interest of this work. It can be used for independent verification of experimental results of the Observatory.
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Cosmic ray showers with anomalous longitudinal profile
Blažek, Jiří ; Trávníček, Petr (advisor) ; Davídek, Tomáš (referee)
Title: Cosmic Ray Showers with Anomalous Longitudinal Profile Author: Jiří Blažek Department: Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University Supervisor: RNDr. Petr Trávníček, Ph.D., Institute of Physics ASCR Abstract: The aim of this work was to study high-energy cosmic ray showers with anomalous longitudinal profiles generated by Monte-Carlo simulation and subse- quently use the acquired analysis techniques on results from the Pierre Auger Observatory (PAO) in Argentina. Firstly, a short introduction of various de- scriptions of the extensive air showers was given. Then a systematic analysis was performed on approx. 7 × 105 simulated showers with three different tech- niques. A brief explanation of the functionality of the PAO was given, then the importance of monitoring the immediate state of the atmosphere using the Shoot- the-Shower program was elucidated and the FRAM telescope was described in detail. FRAM enabled an identification of showers with a clear atmospheric back- ground, this sample of showers was then analyzed and several interesting events warranting a further study were chosen. Keywords: Pierre Auger Observatory, Extensive Air Showers, Chemical Compo- sition, Anomalous Longitudinal Profile, Gaisser-Hillas Function
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Measurement of the inclusive jet cross-section with the ATLAS detector
Pleskot, Vojtěch ; Davídek, Tomáš (advisor) ; Starovoitov, Pavel (referee) ; Taševský, Marek (referee)
The Large Hadron Collider is an accelerator based in the European Organization for Nuclear Research (CERN). It accelerates protons to the highest energies ever reached by the mankind. The ATLAS experiment records data from the proton-proton collisions. Common objects born in the collisions are jets, i.e. collimated bursts of hadrons. This thesis presents the newest ATLAS measurement of the inclusive jet cross-section. The data sample used was recorded in 2011 at 7 TeV centre-of-mass energy. Calorimeter is the most important part of ATLAS for the jet reconstruction. During the data taking, the hadronic calorimeter faced several failures of its components, modules. These non-operating parts have important impact on the jet energy measurement. The thesis describes tests of two available software corrections of the affected jet energies. 1
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Monte Carlo Simulations of the Tile Calorimeter and Measurement of the Z→ττ Cross Section with the ATLAS Detector
Nováková, Jana ; Davídek, Tomáš (advisor) ; Trávníček, Petr (referee) ; Taševský, Marek (referee)
Title: Monte Carlo Simulations of the Tile Calorimeter and Measurement of the Z → ττ Cross Section with the ATLAS Detector Author: Mgr. Jana Nováková Department: Institute of Particle and Nuclear Physics (IPNP) Supervisor: RNDr. Tomáš Davídek, PhD., IPNP Supervisor's e-mail address: davidek@ipnp.troja.mff.cuni.cz Abstract: The Monte Carlo simulations of the Tile calorimeter in the ATLAS experiment at the LHC, especially the electronic noise and multiple interactions (co-called pile-up), are discussed in the thesis. A good agreement in the cell energy distribution between data and Monte Carlo simulations is found. The cross section measurement of Z → ττ events with the ττ invariant mass between 66 and 116 GeV with the ATLAS experiment is described in the next part of the thesis. Data samples collected during 2011 corresponding to the integrated luminosity of 1.34 - 1.55 fb−1 are used for the analysis. The measurements are performed in three different final states depending on the decay mode of the τ leptons. The measurement in the channel with one τ lepton decaying leptonically into the electron + neutrinos (schematically τ → e + νe + ντ ) and the other one hadronically (schematically τ → hadrons + ντ ), especially the calculation of the nominal cross section and the evaluation of the systematic...
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