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Study of B-meson decays in the Belle experiment
Krištof, Michal ; Doležal, Zdeněk (advisor) ; Davídek, Tomáš (referee)
In the thesis we study the decay of B0 meson to D∗ s and ρ mesons. The thesis explains the methods and approaches to data analysis in so-called B-factories, simmilar to the KEKB accelerator. The aim of this thesis is to calculate the branching fraction of this decay to further improve the previously measured branching ratio at BaBar experiment with additional data gained from an ex- periment with higher integrated luminosity. This thesis's prospect is not only broadening our knowledge of branching fractions of B0 meson decays, but also it is a starting point for further analysis with the goal of broadening our knowl- edge of CP symmetry violation in the Standard Model by measuring angles of the Unitary Triangle. 1
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Presentation of particle detectors for public
Knot, Josef ; Doležal, Zdeněk (advisor) ; Dolejší, Jiří (referee)
This diploma thesis deals with particle detectors and their use. In the introduction the reader becomes familiar with concepts of radioactivity and radiation. Next part tells the reader how nuclear radiation penetrates through matter and how this is used for particle detection. Next part presents utilizing radiation in nuclear medicine and medical imaging. The main part of this work concentrates on the design and preparation of an original high school experiment. Here the aim of this experiment is described and its design and implementation is documented. Last part brings the description of technical solutions used, steering computer program developed for this experiment and results of tests.
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Map Information System
Doležal, Zdeněk ; Kopecký, Michal (advisor) ; Skopal, Tomáš (referee)
This work describes design and implementation of a system for on-line displaying multileveled maps in the modern web browsers. The system supports operation with multilayer maps, smooth moving of the map with variable count of the map levels in different areas, searching for routes as well as points of interest and their showing in the map. It is supposed that there will be several client applications running on the system with their own user interfaces. These applications can modify the standard functions of the system which ensures their independency and scalability.
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Testování polovodičových detektorů typu DEPFET
Malina, Lukáš ; Kodyš, Peter (advisor) ; Doležal, Zdeněk (referee)
DEPFET pixel detectors were developed more than 20 years ago and they are still being improved, for example on Belle II experiment in Japan. In this thesis we studied the properties of readout cycle of detector matrix and the movement of counted hit positions close to the edges of DEPFET matrix, the which is reffered to as edge effect. The main goal of this work was to familiarize with particle detectors and their principles, especially with DEPFET matrices, to set up laser test system and to write ROOT macro for measurement automatization, run the measurement and analyze obtained data. For this purpose we used red 3 nanosecond long laser pulses, moving stages with very fine step and two connected pulse generators. As a result, the voltage between the outer ring and the inner part of the detector active area was optimalised, the edge effect was reduced by a factor of 2. The time properties of readout cycle, the time period of charge clearing and the time in which is the matrix read out, have been found.
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Development of optimal algorithms for the selection of rare semimuonic B decays in ATLAS
Scheirich, Daniel ; Doležal, Zdeněk (advisor) ; Mašík, Jiří (referee)
In this thesis we propose the trigger algorithm for the semimuonic rare B decay selection in ATLAS experiment and we study its performance using the Monte Carlo sample of b 0u+u. The cut optimisation have been performed in order to obtain the optimal cut values and the signal rate for the process was estimated. The feasibility and performance of the tag-and-probe method for the calibration of di-muon triggers is investigated, too. Eects of the systematic uncertainties of the method on the measurements of J/ polarisation and the forward-backward asymmetry of b 0u+u were studied.
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Studium procesů s účastí kvarku b v experimentu Belle
Červenkov, Daniel ; Doležal, Zdeněk (advisor) ; Kepka, Oldřich (referee)
Title: Study of b-quark processes in the Belle experiment Author: Daniel Červenkov Department: Institute of Particle and Nuclear Physics Supervisor: Zdeněk Doležal Co-Supervisor: Karim Trabelsi Abstract: A study regarding the plausability of using the B0 → D∗ ρ± decay channel and the data set of the Belle experiment to measure sin(2φ1+φ3) has been carried out. Two fitters have been created. A time-independent one, which ex- hibits high stability and reports gratifying fit uncertainties, and a time-dependent one. During the testing of the latter we have discovered an EvtGen flaw and pro- posed a temporary workaround. Nevertheless, the time-dependent fitter fails to recover the correct values. More work will be needed to reach conclusive results. Keywords: B meson, CP violation, angular analysis, time-dependent, fitter
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Rozpoznávání drah částic v pixelovém detektoru typu Timepix
Čermák, Jakub ; Čermák, Pavel (advisor) ; Doležal, Zdeněk (referee)
In current particle physics field, the progressive detection technologies are used. The pixel detectors are one of them. These detectors are divided into small subdetectors (pixels), which allow viewing exact tracks of the detected particles. This thesis defines criteria for mathematical description of the shape of the particle tracks of different kinds (e-, γ, p, α, μ) and compares several methods used for a classification -neural networks, decision trees and others. The Pixa software was implemented to process the data measured by pixel detectors. This software implements the characteristics and classification methods and creates statistical and other physical results.
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Modernizace vnitřního detektoru ATLAS
Mészárosová, Lucia ; Doležal, Zdeněk (advisor) ; Mikeštíková, Marcela (referee)
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.
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