• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Doctoral Thesis
DOI
10.11606/T.43.2009.tde-07042009-161106
Document
Author
Full name
Marcelo Gimenez Del Santo
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Munhoz, Marcelo Gameiro (President)
Anjos, Roberto Meigikos dos
Guimaraes, Valdir
Kodama, Takeshi
Ribas, Roberto Vicencotto
Title in Portuguese
Estudo de reações nucleares de interesse astrofísico utilizando o método do cavalo de tróia
Keywords in Portuguese
Astrofísica estelar
Física nuclear
Métodos do cavalo de tróia
Reações nucleares
Abstract in Portuguese
A Astrofísica Nuclear é a chave para explicar, entre outras coisas, a produção de energia nas estrelas, a evolução estelar e a síntese de elementos químicos e seus isótopos no Universo. Nesses casos, as reações nucleares formam a estrutura principal, cujas seções de choque e taxas de reação precisam ser determinadas com bastante precisão em laboratório. Devido às condições extremas encontradas nas estrelas, o entendimento dos processos nucleares que ocorrem em seus interiores se tornaram um grande desafio para os físicos nucleares teóricos e experimentais. Nos últimos 40 anos, os físicos vem medindo as taxas dessas reações, porém, as incertezas nesses valores são altas em razão das dificuldades experimentais encontradas nas medidas de seção de choque de processos que ocorrem em energias extremamente baixas (região do pico de Gamow). Desta forma, apenas em alguns casos é possível medir diretamente a seção de choque e o comportamento em baixas energias é geralmente extrapolado da região de energias mais altas. Para evitar o procedimento da extrapolação, alguns métodos indiretos estão sendo 5 usados com sucesso nos últimos anos. Em particular, o método do Cavalo de Tróia permite obter o fator astrofísico S(E) de reações nucleares envolvendo partículas carregadas a baixas energias sem necessidade de extrapolação e sem o efeito da blindagem eletrônica. As reações 10B(p,a)7Be e 11B(p,a)8Be são as principais responsáveis pela queima do boro em estrelas do grupo F e G da sequência principal. As respectivas seções de choque já foram obtidas em experimentos diretos anteriores, porém, os dados não chegam na região do pico de Gamow e o comportamento do fator astrofísico é extrapolado de energias mais altas. Neste trabalho, obteve-se o fator astrofísico S(E) das reações 10B(p,a)7Be e 11B(p,a)8Be através do método indireto do Cavalo de Tróia (THM) aplicado às reações de três corpos 2H(10B,a7Be)n e 2H(11B,a8Be)n sem necessidade de extrapolação. O fator astrofísico obtido por meio do THM para a reação 10B(p,a)7Be é duas vezes menor na região do pico de Gamow comparado com estudos diretos anteriores. Para a reação 11B(p,a)8Be foram estudados separadamente os canais a0 e a1 e o fator astrofísico obtido por meio do THM está de acordo com os estudos diretos anteriores.
Title in English
Study of nuclear reactions of astrophysics interest through the trojan horse method
Keywords in English
Nuclear physics
nuclear reactions
Stellar astrophysics
trojan horse method
Abstract in English
Nuclear Astrophysics is the key to explain, among other things, the production of energy in stars, stellar evolution and the synthesis of chemical elements and isotopes in the Universe. In such cases, nuclear reactions are the main structure, where cross sections and reaction rates must be determined with reasonable accuracy in the laboratory. Because the extreme conditions found in stars, the understanding of nuclear processes that occur in their interiors have become a big challenge for theoretical and experimental nuclear physicists. In the last 40 years, physicists are getting the rates of these reactions but the uncertainty in these values are high due to difficulties found in the experimental cross section measurements at very low energies (Gamow peak region). Thus, only in some cases it is possible to measure directly the cross section and the behavior at low energies is usually extrapolated from the region of higher energy. To avoid the procedure of extrapolation, some indirect methods are being used successfully in recent years. In particular, the Trojan Horse Method gives the Astrophysics 7 S(E) factor of nuclear reactions involving charged particles at low energies without extrapolation and without electron screening effects. The reactions 10B(p,a)7Be and 11B(p,a)8Be are the main responsible for the burning process of boron inside F and G main sequence stars. The cross sections of these reactions have been obtained in previous direct experiments, but the data did not reach the Gamow peak and the behavior of the S(E) factor is then extrapolated from higher energies. In this work, we extract the S(E) factor for the reactions 10B(p,a)7Be and 11B(p,a)8Be through the indirect Trojan Horse Method (THM) applied to the three body reactions 2H(10B,a7Be)n e 2H(11B,a8Be)n without extrapolation. The astrophysical S(E)-factor for the 10B(p,a)7Be reaction was extracted by means of the THM and it is a factor 2 less in the Gamow peak if compared with previous direct studies. For the 11B(p,a)8Be reaction both a0 e a1 channels were studied by means of the THM and the astrophysical S(E)-factor extracted is in good agreement with direct previous studies.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
tese_Marcelo2009.pdf (3.65 Mbytes)
Publishing Date
2009-04-09
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • Oliveira, R.A.N., et al. Study of 9Be+12C elastic scattering at energies near the Coulomb barrier [doi:10.1016/j.nuclphysa.2011.02.005]. Nuclear Physics. A [online], 2011, vol. 856, p. 46-54.
  • Souza, F. A., et al. Projectile breakup dynamics for 6Li + 59Co : Kinematical analysis of $ alpha$ - d coincidences [doi:10.1140/epja/i2010-10940-0]. European Physical Journal. A, Hadrons and Nuclei [online], 2010, vol. 44, p. 181-187.
  • Souza, F.A., et al. Reaction mechanisms in the 6Li+59Co system [doi:10.1016/j.nuclphysa.2009.02.009]. Nuclear Physics A [online], 2009, vol. 821, p. 36-50.
  • Lamia, L., et al. Indirect study of 11B(p,?0?0)8Be and 10B(p,?)7Be reactions at astrophysical energies by means of the Trojan Horse Method: recent results [doi:10.1016/j.nuclphysa.2010.01.115]. In 10th International Conference on Nucleus-Nucleus Collisions, Beijing, 2009. Nuclear Physics. A ., 2010.
  • PUGLIA, S, et al. S(E)-factor for (p,alpha) induced reactions on B-11,B-10. In FROM STARS TO GALAXIES: BUILDING THE PIECES TO BUILD UP THE UNIVERSE, Veneza. ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES.São Francisco, EUA : ASTRONOMICAL SOC PACIFIC,, 2008.
  • ROMANO, S, et al. Boron Stellar Depletion: indirect measurement of the 10B(p,alpha)7Be S(E)-factor. In 9th International Conference on Nucleus-Nucleus Collisons, Rio de Janeiro, 2007. Nuclear Physics A.Amsterdan : Elsevier Science, 2007.
  • SANTO, M G Del, et al. The astrophysical 10B(p,alpha)7Be reaction via the Trojan Horse Method. In International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos IX, Genebra, 2006. Abstract.
  • SANTO, M G Del, et al. The Pelletron-Linac Neutron Wall. In XXVIII Reunião de Trabalho de Física Nuclear no Brasil, Guarujá, 2005. Resumo.
  • SPITALERI, C, et al. New results on the Trojan Horse Method applied to the B-10,B-11+p reactions. In 6th Japan-Italy Symposium on Heavy-Ion Physics, Tokai, 2008. PERSPECTIVES IN NUCLEAR PHYSICS. : AIP Conference Proceedings, 2009.
  • Beck, C., et al. Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets [doi:10.1016/j.nuclphysa.2010.01.059]. In 10th International Conference on Nucleus-Nucleus Collisions, Beijing, 2009. Nuclear Physics. A . : Elsevier, 2010.
  • Figueiredo, M A S, et al. Estudo da viabilidade da medida da reação 12C(n,gamma)13C por meio do método de dissociação Coulombiana. In XXX Reunião de Trabalho sobre Física Nuclear no Brasil, Águas de Lindóia, 2007. Programa e Resumos., 2007. Resumo.
  • LAMIA, L, et al. Indirect measurements for (p,alpha) reactions involving boron isotopes. In 9th Torino Workshop on Evolution and Nucleosynthesis in AGB Stars/2nd Perugia Workshop on Nuclear Astrophysics, Perugia, 2007. NINTH TORINO WORKSHOP ON EVOLUTION AND NUCLEOSYNTHESIS IN AGB STARS AND THE SECOND PERUGIA WORKSHOP ON NUCLEAR ASTROPHYSICS.MELVILLE, NY - USA : AMER INST PHYSICS, 2008.
  • NEGRAO, R., et al. Study of 9Be Break-up Reactions at Energies Near the Coulomb Barrier. In 9th International Conference on Nucleus-Nucleus Collisions, Rio de Janeiro. Abstract Book., 2006. Abstract.
  • NEGRAO, R., et al. Study of the 9Be+12C reaction at energies near the Coulomb Barrier. In XXX Reunião de Trabalho sobre Física Nuclear no Brasil, Águas de Lindóia, 2007. Programa e Resumos., 2007. Abstract.
  • oliveira r n a, et al. Study of 9Be break-up reactions at energies near Coulomb barrier. In XXXI Reunião de Trabalho sobre Física Nuclear no Brasil, São Sebastião, 2008. Programa e Resumos., 2008. Abstract.
  • ROMANO, S, et al. The Trojan horse method in nuclear astrophysics: recent results [doi:10.1088/0954-3899/35/1/014008]. In 3rd Europhysics Conference on Nuclear Physics in Astrophysics (NPA3), Dresden, 2007. Journal of Physics. G, Nuclear and Particle Physics., 2008.
  • Souza, F.A., et al. 6Li direct breakup lifetimes [doi:10.1016/j.nuclphysa.2010.01.054]. In 10th International Conference on Nucleus-Nucleus Collisions, Beijing, 2009. Nuclear Physics. A . : Elsevier, 2010.
All rights of the thesis/dissertation are from the authors
Centro de Informática de São Carlos
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2020. All rights reserved.