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Measurement of scintillator light yield nonlinearity in the neutrino experiment JUNO
Tměj, Tomáš ; Vorobel, Vít (advisor) ; Krtička, Milan (referee)
In order to be able to determine neutrino mass hierarchy in the neutrino oscillation experiment JUNO we need to understand the dependence of the response of the signal from the scintillator on the deposited energy inside the scintillator. We measure the nonlinearity of the signal response via the Compton scattering inside the scintillator and via the precision gamma spectroscopy inside the HPGe detector. We observe effects of different parameters on the experiment via the Monte Carlo simulations. We also improve the data processing of the measured data and discuss what improvements of the experiment we can use in the future.
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Study of Detection Performance of Silicon Strip Sensors for ATLAS ITk Upgrade Project
Latoňová, Věra ; Mikeštíková, Marcela (advisor) ; Vorobel, Vít (referee)
The upgrade of the Large Hadron Collider into the High Luminosity Large Hadron Collider requires a complete replacement of the ATLAS Inner Detector by a new all-silicon Inner Tracker. For this reason a new micro-strip sensor type n+ -in-p was developed. These sensors are expected to have many advantages, such as higher radiation resistance, the ability to operate even if not fully de- pleted and faster response. The main purpose of this thesis is to study and evaluate the detection performance and radiation hardness of the n+ -in-p sen- sor type with the help of electrical characteristics performed on the delivered sensors. The obtained results are compared to the Market Survey Step-2 require- ments and in the case of the sensors designed for the ATLAS Inner Tracker also to the corresponding Technical Specification document. 1
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Neutrino physics at NOvA experiment
Králik, Róbert ; Soustružník, Karel (advisor) ; Vorobel, Vít (referee)
Title: 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: This thesis describes neutrino phenomenology, with special aim at the phenomenon of sterile neutrinos and its experimental study, particularly in the NOvA experiment. Its aim is to clearly and comprehensibly introduce sterile neutrinos in context of historical and present measurements and discoveries. A brief summary of neutrino history is shown, as well as the theory of neutrino oscillations, including a description of matter effects and the effect of adding sterile neutrinos on the oscillation probabilities. NOvA experiment is presented, describing the neutrino source, the detectors and the used particle identification methods. Different experiments for the study of sterile neutrinos are listed and shortly described, with special concentration on the NOvA experiment and its measurement via the neutral-current channel. A detailed description of the first NOvA sterile neutrino result is provided, as well as the aspects of NOvA's current sterile neutrino analyses. Keywords: neutrino, neutrino oscillations, sterile neutrinos, NOvA experiment 1
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Two- neutrino double beta decay of 150Nd in the NEMO-3 experiment and scintillator characterization for the SUPER NEMO
Žukauskas, Aivaras ; Vorobel, Vít (advisor) ; Lokajíček, Miloš (referee) ; Wagner, Vladimír (referee)
The half-life of two-neutrino double beta decay of 150 Nd has been measured with data taken by the NEMO-3 experiment at the Modane Underground Laboratory. Using 1918.5 days of data recorded with 36.55 g of 150 Nd the half-life of this process is measured to be T2ν 1/2 = (8.99 ± 0.18 (stat.) ± 0.71 (syst.)) × 1018 y. SuperNEMO is the successor to NEMO-3 and will be one of the next generation of 0νββ experiments. It aims to measure 82 Se with an half-life sensitivity of 1026 yr corresponding to ⟨mββ⟩ < 50 - 100 meV. In order to achieve this target, a testing apparatus for the scintillator characterization has been developed and 140 scintillator blocks were characterized for the calorimeter of the SuperNEMO. It was determined that none of the blocks violate defined criteria of uniformity (± 3% for the energy resolution at 1 MeV) nor the criteria of energy resolution (< 16% at 1 MeV). The average uniformity of the blocks was found to be 0.7% and the average energy resolution of these blocks is 12% at 1 MeV. However, it was discovered during the visual tests that 23 out of 140 blocks contain more than 20 visible dust specks, thus alarming the possible contamination of these blocks with the natural radioactive isotopes.
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Linearity of light yield in JUNO neutrino experiment
Tměj, Tomáš ; Vorobel, Vít (advisor) ; Krtička, Milan (referee)
The aim of the work is measurement of linearity of liquid scintillator light yield. Knowledge of deviation from the light yield linearity is essential for interpretation of the data measured in the neutrino experiment JUNO. The method is based on use of Compton scattering in the tested scintillator and on precise spectroscopy of the scattered gamma radiation.
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Precise measurement of the electron antineutrino oscillation
Pěč, Viktor ; Vorobel, Vít (advisor) ; Trávníček, Petr (referee) ; Vénos, Drahoslav (referee)
The Daya Bay experiment is designed to precisely measure short-baseline disappearance of reactor antineutrinos from reactor cores at the Daya Bay nuclear power plant complex in the Guangdong Province of China. It pre- sented the most precise measurements of oscillation parameters sin2 2θ13 = 0.084 ± 0.005 and |∆m2 ee| = (2.42 ± 0.11) × 10−3 eV2 . Background to the antineutrino signals is mainly created by cosmic muons and is effectively suppressed by use of water Cherenkov and RPC muon detectors. This thesis describe testing of RPC detectors prior to their installation at the experi- mental site. Part of the cosmic muons stop in the experiment's antineutrino detectors, and they decay or are captured by 12 C producing 12 B. Isotope 12 B contribute to accidental background. Rates of muon decays in the detectors are estimated in the thesis. The experiment can register electron antineutri- nos from supernova with expected signals around 20 MeV. Energy scale of the detectors at 53 MeV is determined.
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Monitoring of the energy scale in the KATRIN neutrino experiment
Slezák, Martin ; Vénos, Drahoslav (advisor) ; Štekl, Ivan (referee) ; Vorobel, Vít (referee)
The question of the absolute mass scale of neutrinos is of particular interest for particle physics, astrophysics, and cosmology. The KATRIN experiment (KArlsruhe TRItium Neutrino experiment) aims to address the effective electron antineutrino mass from the shape of the tritium β-spectrum with an unprecedented sensitivity of 0.2 eV/c2 . One of the major systematic effects concerns the experimental energy scale, which has to be stable at the level of only a few parts in a million. For its calibration and monitoring the monoener- getic electrons emitted in the internal conversion of γ-transition of the metastable isotope 83m Kr will be extensively applied. The aim of this thesis is to address the problem of KA- TRIN energy scale distortions and its monitoring in detail. The source of electrons based on 83m Kr embedded in a solid as well as the source based on gaseous 83m Kr are studied. Based on the experimental results an approach for the continuous stability monitoring is proposed. 1
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Study of Interactions of Cosmic Rays at Ultra-high Energies
Nečesal, Petr ; Řídký, Jan (advisor) ; Vorobel, Vít (referee) ; Wagner, Vladimír (referee)
This thesis is dedicated to study of interactions of utra-high energy cosmic rays using measured data from the Pierre Auger Observatory, automatic alarm system called Shift Guard and analysis of correlation of temperature and detector response. The Pierre Auger Observatory is the largest experiment to study ultra-high energy cosmic rays. The assumed relation between temperature and fluorescence detector response is studied together with descriptive temperature analysis, which shows that the air-conditioning system is not able to stabilize temperature enough. The temperature influence on camera response is investigated in order to measure the calibration correction factor. Shift Guard - the alarm system dedicated to protect fluorescence detectors and data taking is introduced and its functionality is described. The alarm system informs shifters about some events and situations that can endanger detector or deteriorate data quality. The basic parameters and alarm system logic are described together with light and sound signals. The discrepancy between measured and predicted number of muons at ground level calculated by EAS generators is showed and possible sources of this disagree- ment are studied. The result of massive dark photons decay in EAS as one of exotic muon source is presented. The analysis...
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Studium urychlování vysokoenergetických částic v extragalaktických objektech
Štefánik, Stanislav ; Nosek, Dalibor (advisor) ; Vorobel, Vít (referee)
Title: Study of Cosmic-Ray Acceleration in Extragalactic Objects Author: Stanislav tefnik Department: Institute of Particle and Nuclear Physics Supervisor: RNDr. Dalibor Nosek, Dr. Abstract: This thesis deals with production processes of cosmic γ-rays in astro- physical objects and methods of their detection. Possible interactions leading to the emission of high energy γ-rays in the active galaxy Centaurus A are discussed in this context. Cherenkov Telescope Array is presented as a new experiment fo- cused on the detection of air showers initiated by cosmic γ-rays. Cherenkov light of air showers is studied in the simulations done by CORSIKA simulation tool. Method of data analysis within the framework of Cherenkov telescopes is descri- bed and performed on the dataset of the active galaxy PKS 2155-304. The results include statistical tests of γ-ray source presence and its time variability. Keywords: Cosmic rays, gamma rays, astroparticle physics, high energy astro- physics, acceleration, CTA experiment
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Zdroj monoenergetických elektronů pro monitorování spektrometru v neutrinovém experimentu KATRIN
Slezák, Martin ; Vénos, Drahoslav (advisor) ; Vorobel, Vít (referee)
The international project KATRIN (KArlsruhe TRItium Neutrino experiment) is a next- generation tritium beta decay experiment. It is designed to measure the electron antineutrino mass by means of a unique electron spectrometer with sensitivity of 0.2 eV/c2 . This is an improvement of one order of magnitude over the last results. Important part of the measurement will rest in continuous precise monitoring of high voltage of the KATRIN main spectrometer. The monitoring will be done by means of conversion electrons emitted from a solid source based on 83 Rb decay. Properties of several of these sources are studied in this thesis by means of the semiconductor gamma-ray spectroscopy. Firstly, measurement of precise energy of the 9.4 keV nuclear transition observed in 83 Rb decay, from which the energy of conversion electrons is derived, is reported. Secondly, measurement of activity distribution of the solid sources by means of the Timepix detector is described. Finally, a report on measurement of retention of 83 Rb decay product, the isomeric state 83m Kr, in the solid sources is given.
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