National Repository of Grey Literature 3 records found  Search took 0.00 seconds. 
Study of statistical decay in well deformed rare-earth nuclei
Valenta, Stanislav ; Krtička, Milan (advisor) ; Pospíšil, Stanislav (referee) ; Veselý, Petr (referee)
The γ decay of highly excited nuclear levels can be described within the statistical model of nucleus in terms of the level density and a set of photon strength functions. The knowledge of these quantities enables more accurate calculations of reaction rates in many different reactions which are important especially in nuclear astrophysics and in the development of advanced nuclear reactors. Despite the fact that the photon strength functi- ons have been studied for decades, there are still contradicting experimental results regarding the low energy behavior of dipole strength. One of these ca- ses is the shape of electric dipole photon strength function and the strength of the scissors mode in well-deformed rare-earth nuclei. In this thesis the ana- lyses of γ-ray spectra measured by two different experimental setups are pre- sented. The two-step γ cascades measurements with odd gadolinium targets were performed at the research reactor LVR-15 at the Research Centre Řež. In the multi-step γ cascades experiments the γ rays following resonance ne- utron capture on 161−163 Dy targets were measured with the highly-segmented γ-ray calorimeter Detector for Advanced Neutron Capture Experiments in the Los Alamos Neutron Science Center at Los Alamos National Labora- tory. Experimental spectra were compared...
Photon strength functuins in 177Lu from two-step gamma cascade measurement
Valenta, Stanislav ; Krtička, Milan (advisor) ; Kvasil, Jan (referee)
The subject of the study made in this work are photon strength functions. Many models, both based on theoretical as well as phenomenological approaches, were proposed for these quantities, describing the gamma decay of the nucleus, during last 50 year. However, the correctness of these models is still questionable and its verification is the subject of intensive experimental and theoretical activity at the present time. The results of the analysis of measurements of the two-step cascades following thermal neutron capture on the 176Lu nucleus are compared with the outputs of the Monte Carlo simulations based on the validity of the so-called Extreme Statistical Model. Comparison of experimental data with outcomes of simulations thus becomes the basic tool for studying correctness of theoretical models. The experiment analyzed in the present work provides information mainly about E1 and M1 photon strength functions, especially about the so-called scissors resonance.

See also: similar author names
1 Valenta, Samuel
1 Valenta, Štěpán
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