Spectator invariance test in the study of the Li-6,Li-7 fusion reactions via the Trojan Horse Method
Pizzone, R. G.; Lamia, L.; Bertulani, C. A.; Mukhamedzhanov, A.; Spitaleri, C.; Blokhinstev, L.; Burjan, Václav; Cherubini, S.; Hons, Zdeněk; Kiss, G. G.; Kroha, Václav; La Cognata, M.; Li, C.; Mrázek, Jaromír; Piskoř, Štěpán; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Tumino, A.
2011 - English Fusion reactions play a crucial role for several astrophysical scenarios. At the low energies typical of such environments direct measurements of reaction cross sections are very difficult, and even sometimes impossible. In such cases the use of indirect methods can give a substantial help. The Trojan Horse Method (THM) is based on the quasi-free break-up of a nucleus, which can be described in terms of a cluster structure. In such applications the independence of THM results with different break-up schemes, was tested using the quasi free(3)He(Li-6,alpha alpha)H and He-3(Li-7,alpha alpha)H-2 reactions. Results were then compared with the direct behaviours obtained from available data as well as with the cross sections extracted from previous indirect investigations of the same binary reactions using a different nuclide as a Trojan Horse nucleus. Keywords: fusion reactions; indirect methods; cross section Available at various institutes of the ASCR Spectator invariance test in the study of the Li-6,Li-7 fusion reactions via the Trojan Horse Method

Fusion reactions play a crucial role for several astrophysical scenarios. At the low energies typical of such environments direct measurements of reaction cross sections are very difficult, and even ...

Pizzone, R. G.; Lamia, L.; Bertulani, C. A.; Mukhamedzhanov, A.; Spitaleri, C.; Blokhinstev, L.; Burjan, Václav; Cherubini, S.; Hons, Zdeněk; Kiss, G. G.; Kroha, Václav; La Cognata, M.; Li, C.; Mrázek, Jaromír; Piskoř, Štěpán; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Tumino, A.
Ústav jaderné fyziky, 2011

High accuracy O-18(p, alpha)N-15 reaction rate in the 8 . 10(6)-5 . 10(9) K temperature range
La Cognata, M.; Spitaleri, C.; Mukhamedzhanov, A.; Banu, A.; Cherubini, S.; Coc, A.; Crucilla, V.; Goldberg, V.; Gulino, M.; Irgaziev, B.; Kiss, G. G.; Lamia, L.; Mrázek, Jaromír; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Tabacaru, G.; Trache, L.; Tribble, R. E.; Trzaska, W.; Tumino, A.
2011 - English The O-18(p, alpha)N-15 reaction is of great importance in several astrophysical scenarios, as it influences the production of key isotopes such as F-19, O-18 and N-15. In this work, a high accuracy O-18(p, alpha) N-15 reaction rate is proposed, based on the simultaneous fit of direct measurements and of the results of a new Trojan Horse experiment. In particular, we have focused on the study of the broad 660 keV 1/2(+) resonance. Since Gamma similar to 100 - 300 keV, it strongly influences the nearly-zero-energy region of the cross section by means of the low-energy tail of the resonant contribution and dominates the cross section at higher energies. Here we provide a factor of 2 larger reaction rate above T similar to 0.510(9) K based over our new improved determination of its resonance parameters. Keywords: nuclear reactions; nycleosynthesis; abundances Available at various institutes of the ASCR High accuracy O-18(p, alpha)N-15 reaction rate in the 8 . 10(6)-5 . 10(9) K temperature range

The O-18(p, alpha)N-15 reaction is of great importance in several astrophysical scenarios, as it influences the production of key isotopes such as F-19, O-18 and N-15. In this work, a high accuracy ...

La Cognata, M.; Spitaleri, C.; Mukhamedzhanov, A.; Banu, A.; Cherubini, S.; Coc, A.; Crucilla, V.; Goldberg, V.; Gulino, M.; Irgaziev, B.; Kiss, G. G.; Lamia, L.; Mrázek, Jaromír; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Tabacaru, G.; Trache, L.; Tribble, R. E.; Trzaska, W.; Tumino, A.
Ústav jaderné fyziky, 2011

Vertex Couplings in quantum Graphs: Approximations by Scaled Schrödinger Operators
Exner, Pavel
2011 - English We review recent progress in understanding the physical meaning of quantum graph models through analysis of their vertex coupling approximations. Keywords: quantum graphs; vertex coupling; tube networks Available at various institutes of the ASCR Vertex Couplings in quantum Graphs: Approximations by Scaled Schrödinger Operators

We review recent progress in understanding the physical meaning of quantum graph models through analysis of their vertex coupling approximations.

Exner, Pavel
Ústav jaderné fyziky, 2011

Characterization of the Nanostructured Nickel Oxide Layers Prepared by Ion Beam Sputtering
Horák, Pavel; Bejšovec, Václav; Lavrentev, Vasyl; Khun, J.; Vrňata, M.
2011 - English Nanostructured nickel oxide layers (thickness cca 100 nm) were prepared by bombardment of nickel foil with ion beam created from a mixture of argon and oxygen. Different volume ratios of argon:oxygen mixture were used, ranging from 4:1 to 1:3. Composition of the resulting layers was analyzed by RBS, morphology by AFM and main crystal orientation of the sample by XRD. The electrophysical properties (resistivity, concentration of charge carriers) were measured by four point Van der Pauw technique and Hall measurement respectively. Prepared samples were characterized in as-deposited state and after annealing with varying temperature of treatment. Chemical composition (i.e. stoichiometry) of the as-deposited samples with different argon: oxygen ratio was related to their electrophysical parameters. Hall measurements are showing majority charge carriers to be electrons - surface concentration (0.5 - 2.3) x 10(21) m(-2) - suggesting prevailing metallic conductivity. Resistivity of the sample is increasing with higher amount of oxygen in gas mixture. The as-deposited layer is almost amorphous with no visible grains on AFM. Keywords: Nickel oxide; Ion Beam Sputtering; Van der Pauw Fulltext is available at external website. Characterization of the Nanostructured Nickel Oxide Layers Prepared by Ion Beam Sputtering

Nanostructured nickel oxide layers (thickness cca 100 nm) were prepared by bombardment of nickel foil with ion beam created from a mixture of argon and oxygen. Different volume ratios of argon:oxygen ...

Horák, Pavel; Bejšovec, Václav; Lavrentev, Vasyl; Khun, J.; Vrňata, M.
Ústav jaderné fyziky, 2011

Using constraint programming in anytime path planner
Zerola, Michal
2011 - English Path planning in one of the critical tasks for autonomous robots. We will study the problem of finding the shortest path for a robot collecting waste spread over the area such that thet robot has a limited capacity and hence during the route it must periodically visit depost/collectors to empty the collected waste. Keywords: Logistika; Autonomní roboti Available at various institutes of the ASCR Using constraint programming in anytime path planner

Path planning in one of the critical tasks for autonomous robots. We will study the problem of finding the shortest path for a robot collecting waste spread over the area such that thet robot has a ...

Zerola, Michal
Ústav jaderné fyziky, 2011

Proton ICCHIBAN 2 & 3: Results of NPI ASCR participant with various types of thermoluminescent detectors
Ambrožová, Iva; Vlček, Bohumil
2011 - English Keywords: Proton ICCHIBAN 2 & 3; thermoluminescent detectors; NPI ASCR Available at various institutes of the ASCR Proton ICCHIBAN 2 & 3: Results of NPI ASCR participant with various types of thermoluminescent detectors

Ambrožová, Iva; Vlček, Bohumil
Ústav jaderné fyziky, 2011

Emergent Phenomena, Morphomatics and Theory of Complexity
Bíla, J.; Krist, Pavel
2011 - English This paper is devoted to knowledge and symbolical environments for grasping of emergent phenomena. Respecting the fact that the origin of shapes of nature has its essence in emergencies the paper turns attention to formalisms for direct work with such “shapes” (Morphomatics). There are described three environments for grasping of emergent phenomena especially environment 2 as a cognitive tool and environment 3 as dynamic relation between Macrostructure and Microstructure emphasizing their mutual interactions. As an example of formalism developed from synthesis of the introduced three environments is illustrated the use of theory of matroids (dual of Fano matroid) for case of supergravity D=11. Keywords: emergent phenomena; sign model; semantic space; macrostructure; microstructure; matroids Available at various institutes of the ASCR Emergent Phenomena, Morphomatics and Theory of Complexity

This paper is devoted to knowledge and symbolical environments for grasping of emergent phenomena. Respecting the fact that the origin of shapes of nature has its essence in emergencies the paper ...

Bíla, J.; Krist, Pavel
Ústav jaderné fyziky, 2011

Neutron diffraction analysis of residual strain/stress distribution in the vicinity of high strength welds
Mráz, Ľ.; Karlsson, L.; Hamak, I.; Vrána, Miroslav; Mikula, Pavol
2010 - English Residual stresses resulting from non homogeneous heat distribution during welding process belong to most significant factor influencing behavior of welded structures. These stresses are responsible for defect occurrence during welding and they are also responsible for crack initiation and propagation at the either static or dynamic load. The significant effect of weld metal chemical composition as well as the effect of fatigue load and local plastic deformation on residual stress distribution and fatigue life have been recognized for high strength steels welds. The changes in residual stress distribution have then positive effect on cold cracking behavior and also on fatigue properties of the welds [1-3]. Several experimental methods, both destructive and non-destructive, such as hole drilling method, X-ray diffraction, neutron diffraction and others, have been used to examine residual stress distribution in all three significant orientations in the vicinity of the welds. The present contribution summarizes the results of neutron diffraction measurements of residual stress distribution in the vicinity of single-pass high-strength-steel welds having different chemical composition as well as the influence of fatigue load and local plastic deformation. It has been observed that the chemical composition of the weld metal has a significant influence on the stress distribution around the weld. Similarly, by aplying both cyclic load or pre-stress load on the specimens, stress relaxation was observed even in the region of approximately 40 mm far from the weld toe. Keywords: residual stress; neutron diffraction Available at various institutes of the ASCR Neutron diffraction analysis of residual strain/stress distribution in the vicinity of high strength welds

Residual stresses resulting from non homogeneous heat distribution during welding process belong to most significant factor influencing behavior of welded structures. These stresses are responsible ...

Mráz, Ľ.; Karlsson, L.; Hamak, I.; Vrána, Miroslav; Mikula, Pavol
Ústav jaderné fyziky, 2010

Multi-(K)over-bar (hyper)Nuclei and Kaon Condensation
Gazda, Daniel; Mareš, Jiří; Friedman, E.; Gal, A.
2010 - English We report on recent relativistic mean-field calculations of multi-(K) over bar nuclei(1,2) which were performed fully and self-consistently across the periodic table. The (K) over bar separation energy B-(K) over bar as well as the nuclear and (K) over bar -meson densities were found to saturate with the number of antikaons in the nuclear medium. Saturation appears robust against a wide range of variations, including the nuclear model used and the type of boson fields mediating the strong interactions. In addition, we have explored properties of kaonic hypernuclei strange systems made of nucleons, hyperons and K- mesons. We observed saturation also in these objects. Since the (K) over bar separation energy B-(K) over bar does not exceed 200 MeV, multi-(K) over bar nuclei lie energetically well above multi-hyperonic nuclei and it is unlikely that kaon condensation could occur in strong-interaction self-bound hadronic matter. Keywords: Kaonic nuclei; relativistic mean field model; kaon condensation Available at various institutes of the ASCR Multi-(K)over-bar (hyper)Nuclei and Kaon Condensation

We report on recent relativistic mean-field calculations of multi-(K) over bar nuclei(1,2) which were performed fully and self-consistently across the periodic table. The (K) over bar separation ...

Gazda, Daniel; Mareš, Jiří; Friedman, E.; Gal, A.
Ústav jaderné fyziky, 2010

Residual Stresses Assessment in Coated Materials: Complementarity between Neutron and X-Ray Techniques
Rogante, M.; Mikula, Pavol; Vrána, Miroslav
2010 - English The residual stress (RS) status induced in the substrate of coated materials by the coating process plays frequently a major role in lending the component’s characteristics. RS assessment can give, thus, a substantial contribution in justifying different cases of failure or else bad performance of coated components due to e.g. the coating delamination or to other occurrences which are not simply interpretable via the conventional mechanical tests or microstructure analyses. The adoption of both neutron diffraction (ND) and X-ray diffraction (XRD) techniques has revealed its usefulness in assessing the RS values in proximity of the coating interface area, respectively, without any layer removal or hole drilling at the extreme surface. Keywords: Polysrystalline materials; Residual stress; Neutron diffraction Available at various institutes of the ASCR Residual Stresses Assessment in Coated Materials: Complementarity between Neutron and X-Ray Techniques

The residual stress (RS) status induced in the substrate of coated materials by the coating process plays frequently a major role in lending the component’s characteristics. RS assessment can give, ...

Rogante, M.; Mikula, Pavol; Vrána, Miroslav
Ústav jaderné fyziky, 2010