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Sterile neutrino physics at NOvA experiment.
Králik, Róbert ; Soustružník, Karel (advisor) ; Zálešák, Jaroslav (referee)
Title: Sterile neutrino physics at NOvA experiment Author: Róbert Králik Institute: Institute of Particle and Nuclear Physics Supervisor: RNDr. Karel Soustružník, Ph.D., Institute of Particle and Nuclear Physics Abstract: NOvA sterile neutrinos search via neutral current (NC) disappearance analysis is moving to a two-detector fit method to be able to fit to a wider range of sterile neutrino oscillations parameters. This introduces among other things a bigger contribution of the neutrino flux systematic uncertainty, which currently makes up the largest overall uncertainty for the ongoing NC disappearance anal- ysis. This thesis focuses on reducing this uncertainty and looks for different ways of making a more precise prediction of the neutrino flux. We point out Horn-Off analysis as the base for doing so and describe the production of a new Horn-Off simulation and the analysis of the Horn-Off results. We were not able to draw any conclusions that would reduce the NC disappearance systematic uncertainty, but the results showed herein can be helpful in the future attempts at a better neutrino flux prediction and a lower neutrino flux systematic uncertainty. Keywords: sterile neutrino neutrino flux NOvA 1
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Study of heavy particle production at D0
Benedikt, Tomáš ; Soustružník, Karel (advisor) ; Žáček, Josef (referee)
This work is about properties of top quark and methods of their measurements, which took place at D0 detector. At the beginning the history of the quark model is summarized followed by introduction to D0 detector at Tevatron collider in the USA. The rest of the work is dedicated to methods of measurements of important top quark properties. The most of attention is paid to measurements of production cross section and top quark's mass. The following topics are decay width, determination of the mass difference between top and antitop quarks and determination od top quark's electrical charge. In the end the newest values of top quark's properties are summarized.
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Proton-Proton Interactions at the ATLAS Experiment at the LHC Accelerator
Přibyl, Lukáš ; Němeček, Stanislav (advisor) ; Soustružník, Karel (referee) ; Kupčo, Alexander (referee)
In this thesis the potential of the ATLAS detector to exclude or discover quark compositeness is studied in detail. There were four dierent sensitive analysis methods developed for this purpose. These methods use a detailed information about inclusive dijet pT-spectrum or dijet angular distribution and two of them use Bayesian technique (as is usual in similar analyses at Tevatron). For all four methods a larger number of systematic errors was taken into account and their inuence was studied in detail too. It is also shown, that the early data exclusion limit on quark compositeness reachable by the ATLAS experiment is + LL = 10.3 TeV at 95% C.L with 100 pb 1 of collision data of a sucient quality. This limit is considerably higher than the current limit known from Tevatron: + LL = 2.7 TeV at 95% C.L. The highest exclusion limit on quark compositeness with expected total amount of data to be collected by the ATLAS experiment is above 22 TeV, assuming 3% jet energy scale uncertainty.
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Study of high energy cosmic gamma rays
Štefánik, Stanislav ; Nosek, Dalibor (advisor) ; Soustružník, Karel (referee) ; Tománková, Lenka (referee)
In this thesis, we present our two studies focused on the detection of cosmic γ-rays and the analysis of data from γ-ray observations. One study deals with the method of the Cherenkov transparency coefficient. This method is suitable for the detector calibration in experiments employing imaging atmo- spheric Cherenkov telescopes for the indirect detection of cosmic γ-rays. Us- ing rates of recorded air showers initiated by charged cosmic rays, the method aims at the monitoring of the atmospheric transparency to Cherenkov light and the calibration of the responses of Cherenkov telescopes. We present an extension of this method for the purposes of the Cherenkov Telescope Array observatory and demonstrate its feasibility using Monte Carlo simu- lations. Our other analysis utilizes more than 7 years of data from direct γ-ray observations by the Fermi Large Area Telescope. We describe in detail signal observed from the parts of the sky around the active galactic nuclei 1ES 0229+200 and Centaurus A. We report on the findings of new astro- physical sources of high energy photons and document spectral and temporal properties of their γ-ray fluxes. 1
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Studium kinematiky rozpadů top-antitopových párů v experimentu Atlas
Berta, Peter ; Kvita, Jiří (advisor) ; Soustružník, Karel (referee)
In this thesis, I deal with the measurement of the transverse momentum spectrum of the top quark produced in top-antitop pairs at the LHC at center of mass energy 7 TeV. The analysis is carried out within the ATLAS collaboration. In the single lepton decay channel, I have performed studies on the simulation which were necessary to obtain the final spectrum from real data. I describe basic event selection rules to reduce background events. I study the efficiency of top-antitop pairs reconstruction. I study the unfolding of the measured spectrum which corrects for effects caused by imperfect resolutions. At the end, I show the measured top quark transverse momentum spectrum obtained from my analysis.
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Top Quark Physics with the ATLAS Detector
Slovák, Radim ; Kvita, Jiří (advisor) ; Soustružník, Karel (referee)
In the presented diploma thesis we study the reconstruction of the top antitop system in proton-proton colisions with central mass energy 7 TeV de- livered by LHC accelerator at CERN to the ATLAS experiment. ALPGEN and MC@NLO generators are described as two main method of top antitop pairs simulations. We compare events simulated by generators to data from LHC. The background and selection criteria are summarized. Next we de- scribed various methods of the top antitop reconstruction. Finally the Z particle was also studied. 1
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Study of neutrino oscillations at the NOvA experiment
Nosek, Tomáš ; Soustružník, Karel (advisor)
NOvA is a two detector long-baseline neutrino oscillation experiment using Fermilab's 700 kW NuMI neutrino beam. It studies the disappearance of muon (anti)neutrinos and the appearance of electron (anti)neutrinos in the beam over a distance of 810 km be- tween the detectors. This thesis presents the latest 2020 update of the NOvA neutrino oscillation analysis within the standard model of three neutrinos mixing. With about +50% new data in NuMI neutrino mode (+22% of the total available data) and nu- merous analysis upgrades compared to the previously reported results, the experiment has made over 4σ-significant observation of electron antineutrino appearance in muon antineutrino beam and constrained the oscillation parameters |∆m2 32|, sin2 θ23 and δCP. The text closely depicts the analysis and all its novelties and changes. A detailed inspec- tion is dedicated to the systematic uncertainties and their estimation and validation. Although statistical uncertainties currently dominate in these measurements, under- standing the major sources of systematic uncertainties and their correlations is vital for both the interpretation and precision of the results and for further improvements of the analysis. 1
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Study of neutrino oscillations at the NOvA experiment
Nosek, Tomáš ; Soustružník, Karel (advisor) ; Roskovec, Bedřich (referee) ; Zálešák, Jaroslav (referee)
NOvA is a two detector long-baseline neutrino oscillation experiment using Fermilab's 700 kW NuMI neutrino beam. It studies the disappearance of muon (anti)neutrinos and the appearance of electron (anti)neutrinos in the beam over a distance of 810 km be- tween the detectors. This thesis presents the latest 2020 update of the NOvA neutrino oscillation analysis within the standard model of three neutrinos mixing. With about +50% new data in NuMI neutrino mode (+22% of the total available data) and nu- merous analysis upgrades compared to the previously reported results, the experiment has made over 4σ-significant observation of electron antineutrino appearance in muon antineutrino beam and constrained the oscillation parameters |∆m2 32|, sin2 θ23 and δCP. The text closely depicts the analysis and all its novelties and changes. A detailed inspec- tion is dedicated to the systematic uncertainties and their estimation and validation. Although statistical uncertainties currently dominate in these measurements, under- standing the major sources of systematic uncertainties and their correlations is vital for both the interpretation and precision of the results and for further improvements of the analysis. 1
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Sterile neutrino physics at NOvA experiment.
Králik, Róbert ; Soustružník, Karel (advisor) ; Zálešák, Jaroslav (referee)
Title: Sterile neutrino physics at NOvA experiment Author: Róbert Králik Institute: Institute of Particle and Nuclear Physics Supervisor: RNDr. Karel Soustružník, Ph.D., Institute of Particle and Nuclear Physics Abstract: NOvA sterile neutrinos search via neutral current (NC) disappearance analysis is moving to a two-detector fit method to be able to fit to a wider range of sterile neutrino oscillations parameters. This introduces among other things a bigger contribution of the neutrino flux systematic uncertainty, which currently makes up the largest overall uncertainty for the ongoing NC disappearance anal- ysis. This thesis focuses on reducing this uncertainty and looks for different ways of making a more precise prediction of the neutrino flux. We point out Horn-Off analysis as the base for doing so and describe the production of a new Horn-Off simulation and the analysis of the Horn-Off results. We were not able to draw any conclusions that would reduce the NC disappearance systematic uncertainty, but the results showed herein can be helpful in the future attempts at a better neutrino flux prediction and a lower neutrino flux systematic uncertainty. Keywords: sterile neutrino neutrino flux NOvA 1
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Study of high energy cosmic gamma rays
Štefánik, Stanislav ; Nosek, Dalibor (advisor) ; Soustružník, Karel (referee) ; Tománková, Lenka (referee)
In this thesis, we present our two studies focused on the detection of cosmic γ-rays and the analysis of data from γ-ray observations. One study deals with the method of the Cherenkov transparency coefficient. This method is suitable for the detector calibration in experiments employing imaging atmo- spheric Cherenkov telescopes for the indirect detection of cosmic γ-rays. Us- ing rates of recorded air showers initiated by charged cosmic rays, the method aims at the monitoring of the atmospheric transparency to Cherenkov light and the calibration of the responses of Cherenkov telescopes. We present an extension of this method for the purposes of the Cherenkov Telescope Array observatory and demonstrate its feasibility using Monte Carlo simu- lations. Our other analysis utilizes more than 7 years of data from direct γ-ray observations by the Fermi Large Area Telescope. We describe in detail signal observed from the parts of the sky around the active galactic nuclei 1ES 0229+200 and Centaurus A. We report on the findings of new astro- physical sources of high energy photons and document spectral and temporal properties of their γ-ray fluxes. 1
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