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Hypernuclear production in K--stopped reactions
Krejčiřík, Vojtěch ; Cieplý, Aleš (advisor) ; Kvasil, Jan (referee)
The thesis focuses on -hypernuclear production induced by K meson stopped at an atomic orbit. Calculations are performed within the framework of the distorted wave impulse approximation. We use a microscopic model based on chiral perturbation theory for the description of the elementary kaon-nucleon process. The use of the microscopic model is one of the assets of the present work. Another novelty is a proper treatment of the pion distortion in the eective nucleon density available for the reaction. We consider several kaon-nucleus and pion-nucleus potentials. We study various eects on the capture rate of the reaction. We compare our results with experimental data and with previous calculations. Although our results are closer to the experimental values then the results of previous authors, the agreement with experiment is still unsatisfactory.
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Study of exotic hypernuclei
Posolda, Petr ; Mareš, Jiří (advisor) ; Kvasil, Jan (referee)
The thesis focuses on the study of properties of exotic hypernuclei, particularly of beryllium, carbon, oxygen and neon isotopes with and hyperons. Calculations were performed in the framework of the relativistic mean field theory (RMF) where a (hyper)nucleus is treated as a system of Dirac spinors (nucleons, hyperons) interacting via (mean) meson fields. The exotic hypernuclei were considered as axial symmetric. Up to now, hypernuclear calculations have been performed under assumption of spherical symmetry. This work thus extends hypernuclear calculations to the region of exotic, generally deformed systems. For the above nuclei, the numerical calculations of the binding energies and root mean square radii were performed. Moreover, we studied influence of the tensor interaction between meson and hyperon on the spin-orbit splitting. The results confirmed that the presence of the hyperon increases values of the binding energy of a system and on the contrary, it decreases its root mean square radius. We studied the possibility of the existence of the hyperon bound states in a nucleus. For the above isotopes, no bound states were found for the + hyperons. On the other hand, weekly bound states of the - hyperon are predicted for several isotopes.
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Analysis of dijet events in diffractive ep interactions with tagged leading proton at the H1 experiment
Polifka, Richard ; Kvasil, Jan (advisor)
Title: Analysis of dijet events in diffractive ep interactions with tagged leading proton at the H1 experiment Author: Richard Polifka Department: Institute of Particle and Nuclear Physics Supervisor: RNDr. Alice Valkárová, DrSc. Supervisor's e-mail address: avalkar@mail.desy.de Abstract: An inclusive dijet production in diffractive deep-inelastic scattering is measured. The diffractive selection is based on tagging of the leading proton in the Forward Proton Spectrometer. The statistics of events obtained during the HERA II running period (integrated luminosity of 156.7 pb−1 ) enables the measurement of jet final states with leading proton for the first time. The data cover the phase space of xIP < 0.1, |t| ≤ 1.0 GeV2 and 4 ≤ Q2 ≤ 110 GeV2 . The dijet data are compared with the next to leading order predictions of the quantum chromodynamics (QCD). The phase space of diffractive dijets is in this analysis by factor of 3 in xIP larger than in previous measurements. The QCD predictions based on the DGLAP parton evolution describe the measured data well even in a non-DGLAP enriched phase space where one on the jets goes into the region close to the direction of the outgoing proton. The measured single-differential cross sections are compared to several Monte Carlo models with different treatment of...
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Microscopic nuclear models for open-shell nuclei
Herko, Jakub ; Knapp, František (advisor) ; Kvasil, Jan (referee)
Title: Microscopic nuclear models for open-shell nuclei Author: Jakub Herko Institute: Institute of Particle and Nuclear Physics Supervisor: Mgr. František Knapp, Ph.D., Institute of Particle and Nuclear Physics Abstract: Since the nucleus is a quantum many-body system consisting of con- stituents whose mutual interaction is not satisfactorily known, it is necessary to use approximate methods when describing the nucleus. Basic approximate approaches in the microscopic theory of the nucleus are the Hartree-Fock the- ory, Tamm-Dancoff approximation and random phase approximation. They are described in the first chapter of this thesis. The main aim was to develop mi- croscopic models for open-shell nuclei with two valence particles or holes. They are described in the second chapter, which contains detailed derivations of the relevant formulae. These methods have been numerically implemented. The re- sults of the calculations of the nuclear spectra and the electromagnetic transition probabilities are presented in the third chapter. Keywords: Tamm-Dancoff approximation, random phase approximation, open- shell nuclei, nuclear spectra, electromagnetic transition probabilities ii
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Giant monopole resonances in deformed nuclei
Božík, Daniel ; Kvasil, Jan (advisor) ; Mareš, Jiří (referee) ; Knapp, František (referee)
Title: Giant monopole resonances in deformed nuclei Author: Daniel Božík Department: Institute of particle and nuclear physics Supervisor: prof. RNDr. Jan Kvasil, DrSc., ÚČJF, MFF UK Abstract: The study of giant monopole resonances is important, because of its di- rect connection to the incompressibility of the nuclear matter, and its importance has risen with new experimental data obtained in recent years from the experi- ments TAMU and RCNP. The current work brings a study of the giant monopole resonances for chains of spherical (Pb, Sn, Zr) as well as deformed (Sm, Mo, Cd) isotopes. The calculations were carried out within the HFB + SRPA method, which was developed at MFF UK in cooperation with JINR Dubna and the University of Erlangen. We were as first able to confirm, from the microscopic theory, the appearance of a double-peak structure of GMR strength functions for deformed nuclei, and its connection with E0-E2 coupling. We showed the importance of using strength functions in the study of GMR. Keywords: HFB, SRPA, giant monopole resonances 1
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Theoretical description of nuclear collective excitations
Repko, Anton ; Kvasil, Jan (advisor) ; Knapp, František (referee) ; Mareš, Jiří (referee)
Density functional theory is a preferred microscopic method for calculation of nuclear properties over the whole nuclear chart. Besides ground-state properties, which are calculated by Hartree-Fock theory, nuclear excitations can be described by means of Random Phase Approximation (RPA). The main objective of the present work is to give the RPA formalism for spherically symmetric nuclei, using the techniques of angular-momentum coupling. Various auxiliary topics, such as Hartree-Fock theory, Coulomb integral, center-of-mass corrections and pairing, are treated as well. RPA method is derived also for axially deformed nuclei. The derived formulae are then implemented in the computer code and utilized for calculation of some physical results. After thorough investigation of the precision aspects of the calculation, the following topics are treated as examples: toroidal nature of the low-energy (pygmy) part of the E1 resonance, giant resonances of various multipolarities in deformed nucleus 154Sm, and magnetic dipole (M1) transitions in deformed 50Cr. Powered by TCPDF (www.tcpdf.org)
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Microscopic calculations of nuclear properties with realistic nucleon-nucleon interaction
Herko, Jakub ; Knapp, František (advisor) ; Kvasil, Jan (referee)
Title: Microscopic calculations of nuclear properties with realistic nucleon-nucleon interaction Author: Jakub Herko Department: Institute of Particle and Nuclear Physics Supervisor: Mgr. František Knapp, Ph.D., Institute of Particle and Nuclear Phy- sics Abstract: A significant problem of nuclear physics is the fact that the nucleus is quantum many-body system consisting of constituents whose mutual interac- tion is unknown. Therefore, it is necessary to use approximative methods when describing the nucleus. In the microscopic theory of the nucleus we often use the mean-field approximation, in which we consider non-interacting nucleons moving in external field. One approach to obtain an optimal mean-field is the Hartree- Fock method. The first part of this work is theoretical and describes methods of the microscopic theory of the nucleus, especially the Hartree-Fock method, with emphasis on formalism of the second quantization. The second part describes a practical implementation of the Hartree-Fock method in calculations of certain properties of the nuclei and calculations that go beyond this method and include the residual interaction using the perturbation theory. Keywords: Hartree-Fock method, nuclear binding energies, single-particle spectra, many-body perturbation theory
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Photon strength functions in Gd isotopes studied from resonance neutron capture
Kroll, Jiří ; Krtička, Milan (advisor) ; Kvasil, Jan (referee) ; Granja, Carlos (referee)
Title: Photon strength functions in Gd isotopes studied from resonance neutron capture Author: RNDr. Jiří Kroll Department: Intitute of particle and nuclear physics Supervisor: doc. Mgr. Milan Krtička, Ph.D., Intitute of particle and nuclear physics Abstract: Photon strength functions have been studied for more than sixty years. A number of theoretical models was proposed to describe experimental data during that time. However, the correctness of these models is still very questionable and its verification is the subject of very intensive experimental and theoretical activity at present time. In this thesis the analysis of spectra of γ rays following the radiative capture of neutrons on isolated neutron resonances of 152,154−158 Gd nuclei is used to study photon strength functions. Experimental data were measured using segmented DANCE calorimeter that is installed at Los Alamos Neutron Scattering Center in New Mexico, USA. Experimental spectra are then compared with the outputs of Monte Carlo simulation of nuclear elec- tromagnetic decay, performed by DICEBOX code, that is based on the validity of the so-called Extreme Statistical Model. The response of the detector system to generated γ cascades was subsequently calculated using the Geant4 code. An analysis of the data clearly indicates that magnetic...
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