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Your search keyword '"Siváček I."' showing total 24 results
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24 results on '"Siváček I."'

1. 26Mg target for nuclear astrophysics measurements

Author

Siváček I., Mrázek J., Kroha V., Burjan V., Glagolev V., Piskoř Š., Spitaleri C., Pizzone R.G., La Cognata M., D’Agata G., Tumino A., Lamia L., Spartá R., Rapisard G.G., and Romano S.

Subjects
Physics, QC1-999
Abstract

Two nuclear reactions of astrophysical interest, 26Mg(3He,d)27Al and 26Mg(d,p)27Mg, were measured for extraction of the Asymptotic Normalization Coefficients. Investigation of the target composition is presented, as well as the effects that showed up during analysis of the in-beam data obtained on CANAM accelerators in the Nuclear Physics Institute of the Czech Academy of Sciences (NPI CAS).

Published
2018
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2. ANC experiments for nuclear astrophysics in NPI CAS

Author

Mrazek J., Burjan V., Kroha V., Mukhamedzhanov A.M., Tribble R., Spitaleri C., Siváček I., Glagolev V., Piskoř Š., Pizzone G.R., La Cognata M., D’Agata G., Tumino A., Lamia L., Sparta R., Rapisarda G., and Romano S.

Subjects
Physics, QC1-999
Abstract

Asymptotic Normalization Coefficients method is one of the indirect methods used in nuclear astrophysics. The method allows to deduce a direct part of a radiative capture cross section from the measurement of a two body reaction under specific conditions. The experimental works started in collaboration of NPI CAS, TAMU and INFN LNS from 90-ties and continue till the present. The introduction to this method is presented and experimental experiences from NPI CAS and the collaboration are shared.

Published
2018
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3. Charged-particle branching ratios above the neutron threshold in $^{19}$F: constraining $^{15}$N production in core-collapse supernovae

Author

Adsley, P., Hammache, F., de Séréville, N., Alcindor, V., é, M. Assi, Chabot, D. Beaumel M., Degerlier, M., Delafosse, C., Faestermann, T., Flavigny, F., Fox, S. P., Garg, R., Georgiadou, A., Gillespie, S. A., Guillot, J., Hertenberger, R., Guimarães, V., Gottardo, A., Kiener, J., Laird, A. M., Lefebvre-Schuhl, A., Matea, I., Meyer, A., Mahgoub, M., Olivier, L., Perrot, L., Riley, J., Sivacek, I., Stefan, I., Tatischeff, V., and Wirth, H. -F.

Subjects
Nuclear Experiment, Astrophysics - Solar and Stellar Astrophysics
Abstract

Spatially-correlated overabundances of $^{15}$N and $^{18}$O observed in some low-density graphite meteoritic grains have been connected to nucleosynthesis taking place in the helium-burning shell during core-collapse supernovae. Two of the reactions which have been identified as important to the final abundances of $^{15}$N and $^{18}$O are $^{18}$F($n,\alpha$)$^{15}$N and $^{18}$F($n,p$)$^{18}$O. The relative strengths of the $^{18}$F($n,\alpha$)$^{15}$N and $^{18}$F($n,p$)$^{18}$O reactions depend on the relative $\alpha_0$ and $p_0$ decays from states above the neutron threshold in $^{19}$F in addition to other properties. Experimental data on the charged-particle decays from these highly excited states are lacking or inconsistent. Two experiments were performed using proton inelastic scattering from LiF targets and magnetic spectrographs. The first experiment used the high-resolution Q3D spectrograph at Munich to constrain properties of levels in $^{19}$F. A second experiment using the Orsay Split-Pole spectrograph and an array of silicon detectors was performed in order to measure the charged-particle decays of neutron-unbound levels in $^{19}$F. A number of levels in $^{19}$F have been identified along with their corresponding charged-particle decays. The first state above the neutron threshold which has an observed proton-decay branch to the ground state of $^{18}$O lies 68 keV above the neutron threshold while the $\alpha$-particle decays from the neutron-unbound levels are generally observed to be much stronger than the proton decays. Neutron-unbound levels in $^{19}$F are observed to decay predominantly by $\alpha$-particle emission, supporting the role of $^{18}$F($n,\alpha$)$^{15}$N in the production of $^{15}$N in the helium-burning shell of supernovae. Improved resonant-scattering reaction data are required in order to be able to determine the reaction rates accurately., Comment: 13 pages, 5 figures, v3 more wrong affiliations

Published
2020
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4. Charged-particle decays of highly excited states in $^{19}$F

Author

Adsley, P., Hammache, F., de Séréville, N., Assié, M., Beaumel, D., Chabot, M., Degerlier, M., Delafosse, C., Flavigny, F., Georgiadou, A., Guillot, J., Guimarães, V., Gottardo, A., Matea, I., Olivier, L., Perrot, L., Stefan, I., Laird, A., Fox, S. P., Garg, R., Gillespie, S., Riley, J., Kiener, J., Lefebvre-Schuhl, A., Tatischeff, V., and Sivacek, I.

Subjects
Nuclear Experiment
Abstract

Neutron-capture reactions on $^{18}$F in the helium-burning shell play an important role in the production of $^{15}$N during core-collapse supernovae. The competition between the $^{18}$F($n,p/\alpha$)$^{18}$O/$^{15}$N reactions controls the amount of $^{15}$N produced. The strengths of these reactions depend on the decay branching ratios of states in $^{19}$F above the neutron threshold. We report on an experiment investigating the decay branching ratios of these states in order to better constrain the strengths of the reactions., Comment: Submitted as part of the Proceedings of NIC 2018

Published
2018
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7. Charged-Particle Decays of Highly Excited States in F

Author

Adsley, P., Hammache, F., de Séréville, N., Assié, M., Beaumel, D., Chabot, M., Degerlier, M., Delafosse, C., Flavigny, F., Georgiadou, A., Guillot, J., Guimaräes, V., Gottardo, A., Matea, I., Olivier, L., Perrot, L., Stefan, I., Laird, A. M., Fox, S. P., Garg, R., Gillespie, S., Riley, J., Kiener, J., Lefebvre-Schuhl, A., Tatischeff, V., Sivacek, I., Formicola, Alba, editor, Junker, Matthias, editor, Gialanella, Lucio, editor, and Imbriani, Gianluca, editor

Published
2019
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12. Separation efficiency of the MASHA facility for short-lived mercury isotopes

Author

Rodin, A. M., Belozerov, A. V., Chernysheva, E. V., Dmitriev, S. N., Gulyaev, A. V., Gulyaeva, A. V., Itkis, M. G., Kliman, J., Kondratiev, N. A., Krupa, L., Novoselov, A. S., Oganessian, Yu. Ts., Podshibyakin, A. V., Salamatin, V. S., Siváček, I., Stepantsov, S. V., Vanin, D. V., Vedeneev, V. Yu., Yukhimchuk, S. A., Granja, C., and Pospisil, S.

Published
2014
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14. Si26(p,γ)P27 direct proton capture by means of the asymptotic normalization coefficients method for mirror nuclei

Author

D'Agata, G., primary, Kilic, A. I., additional, Burjan, V., additional, Mrazek, J., additional, Glagolev, V., additional, Kroha, V., additional, Guardo, G. L., additional, La Cognata, M., additional, Lamia, L., additional, Palmerini, S., additional, Pizzone, R. G., additional, Rapisarda, G. G., additional, Romano, S., additional, Sergi, M. L., additional, Spartà, R., additional, Spitaleri, C., additional, Siváček, I., additional, and Tumino, A., additional

Published
2021
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18. New Insight into the Cluster Structure of 9Be by Reactions with Deuteron Beam

Author

Lukyanov, S. M., primary, Urazbekov, B., additional, Janseitov, D. M., additional, Burjan, V., additional, Denikin, A. S., additional, Trzaska, W. H., additional, Harakeh, M., additional, Etasse, D., additional, Issatayev, T., additional, Kroha, V., additional, Maslov, V. A., additional, Mrazek, J., additional, Mendibayev, K., additional, Naumenko, M. A., additional, Siváček, I., additional, Glagolev, V., additional, Piskor, Š., additional, Penionzhkevich, Yu. E., additional, Skobelev, N. K., additional, Stefan, I., additional, Verney, D., additional, Kuterbekov, K., additional, and Zholdybayev, T., additional

Published
2019
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20. Total Reaction Cross Sections for 6,8He and 9Li Nuclei on 28Si, 59Co, and 181Ta Targets.

Author

Sobolev, Yu. G., Penionzhkevich, Yu. E., Samarin, V. V., Naumenko, M. A., Stukalov, S. S., Siváček, I., Krupko, S. A., Kugler, A., and Louko, J.

Abstract

Experiments with 6,8He, 9Li + 28Si, 59Co, and 181Ta reactions in the energy range of 6,8He and 9Li beams 6–36 A MeV have been preformed. Prompt neutrons and gamma radiation were registered by a 12‑detector gamma spectrometer. The values of the total reaction cross sections and the multiplicity distributions for the emission of γ-quanta and neutrons were calculated taking into account the distributions over the number of triggered detectors. [ABSTRACT FROM AUTHOR]

Published
2020
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21. Measuring the Total Cross Sections for Reactions in Collisions of 6, 8He + 28Si and 9Li + 28Si.

Author

Sobolev, Yu. G., Penionzhkevich, Yu. E., Maslov, V. A., Naumenko, M. A., Samarin, V. V., Siváček, I., and Stukalov, S. S.

Abstract

The total cross sections for the 6, 8He + 28Si and 9Li + 28Si reactions are measured in the beam energy range of 12–39 A MeV via transmission method with registration of prompt neutron and gamma radiation by a spectrometer with six scintillation detectors. The technique taking into account the experimental values ​​of the efficiency of registering gamma radiation with different multiplicities and the number of triggered spectrometer detectors is used to analyze the experimental data. The experimental data are compared to data obtained earlier in other studies. The values ​​of the total cross section for 8He + 28Si reaction at energy around 20 A MeV are close to those ​​of the total cross section for the 6He + 28Si reaction. The total cross section for the 8He + 28Si reaction is appreciably higher than the total cross section for the 6He + 28Si reaction in the range of 12–16 A MeV. [ABSTRACT FROM AUTHOR]

Published
2019
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23. ANC experiments for nuclear astrophysics

Author

D’Agata G., Burjan V., Mrázek J., Glagolev V., Kilic A. I., Kroha V., La Cognata M., Lamia L., Palmerini S., Piskoř Š., Pizzone R. G., Rapisarda G. G., Romano S., Siváĉek I., Spitaleri C., Spartá R., and Tumino A.

Subjects
Physics, QC1-999
Abstract

Among the indirect methods to determine nuclear cross-section present in literature, the so-called Asymptotic Normalization Coefficient (ANC) has proven to be useful in retrieving the direct part of a radiative capture cross-section in reactions of interest for astrophysics. In this work, the method will be presented, and some results obtained in collaboration between NPI CAS and INFN-LNS will be presented.

Published
2020
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24. Energy dependence of the total cross section for the 11Li+28Si reaction.

Author

Penionzhkevich, Yu. E., Sobolev, Yu. G., Samarin, V. V., Naumenko, M. A., Lashmanov, N. A., Maslov, V. A., Siváček, I., and Stukalov, S. S.

Subjects
*NUCLEAR cross sections, *NUCLEAR energy, *NUCLEAR reactions
Abstract

In this paper the results of measurements of the total cross sections for the 11Li+28Si reaction in the beam energy range 7A-25A MeV are presented. The experimental cross sections were obtained by registration of the prompt gamma and neutron radiation accompanying the interaction of 11Li nuclei with 28Si nuclei. The total cross sections for the 11Li+28Si reaction are calculated based on a numerical solution of the time-dependent Schrödinger equation for the external weakly bound neutrons of the projectile nucleus 11Li. The calculated total reaction cross sections are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Published
2019
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