National Repository of Grey Literature 8 records found  Search took 0.00 seconds. 
Photon strength functions in 168Er from multi-step gamma cascade measurement at DANCE
Knapová, Ingrid ; Krtička, Milan (advisor) ; Pěč, Viktor (referee)
Subject of the thesis is study of photon strength functions describing the gamma decay of the nucleus. During last 50 years a number of theoretical models for these quantities were proposed, however, their accuracy is still de- batable and its verification has recently been a subject of intensive experimental and theoretical research. In this work measurement of multi-step gamma cas- cades following the radiative neutron capture on target nucleus 167 Er is used to analyse photon strength functions. The experiment was performed with DANCE calorimeter located in Los Alamos Neutron Scattering Center. The experimen- tal spectra are compared with Monte Carlo simulations of electromagnetic decay using the DICEBOX algorithm, based on assumptions of Extreme Statistical Model. Comparison of experimental and simulated spectra is a fundamental tool for studying correctness of theoretical models of photon strength functions. This study provides information mainly about E1 and M1 photon strength functions, especially properties of the so-called scissor mode are analysed.
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.
Možnosti zkoumání oscilací elektronových (anti) neutrin z rozpadů mionů.
Dohnal, Tadeáš ; Leitner, Rupert (advisor) ; Pěč, Viktor (referee)
In this thesis, the phenomenon of neutrino oscillations is investigated. General phenomenology for the three active neutrino framework is provided, along with transition probabilities in vacuum. The effect of eventual CP violation on neutrino oscillations and difficulties of its measurement are introduced. Several solutions are discussed, especially the concept of the neutrino factory (i.e. using neutrinos from muon decays) as it is projected by the nuSTORM collaboration. Energy spectra of neutrinos from unpolarized muon decays, both at rest and in flight are calculated, along with the angular distribution and other specifications.
Influence of the Detection Threshold on the Response of the C6D6 Detectors
Knapová, Ingrid ; Krtička, Milan (advisor) ; Pěč, Viktor (referee)
Scintillation C6D6 detectors are used for radiative capture cross-section measurements in various neutron time-of-flight facilities (n_TOF in CERN, GELINA in IRMM Geel). To determinate cross-section with the help of Pulse Height Weighting Technique we usually neglect influence of undetectable energy, derived from two phenomena - internal conversion and detection threshold for low photon energies. However, in some cases their impact cannot be completely omitted and due to lack of knowledge it has not been the subject of research yet. The purpose of this thesis is to study the influence of these two effects from simulations of neutron radiative capture induced photon spectra. Two nuclei: 197 Au and 238 U were used for testing.
Current Status of Highest Energy Cosmic Rays
Krejčíková, Martina ; Nosek, Dalibor (advisor) ; Pěč, Viktor (referee)
The Earth is constantly bombarded by extra-high energy particles, which can not reach any man-made accelerator. Cosmic Rays have been studied over a hundred years, nevertheless we are not able to answer the questions about sources, arriving directions and composition. In the following work there are de- scribed the important projects that occupy the problems, the methods of data analysis and comparison of available experimental results. 1

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