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Doctoral Thesis
DOI
https://doi.org/10.11606/T.43.2006.tde-22012007-153428
Document
Author
Full name
Francisco de Assis Souza
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2006
Supervisor
Committee
Carlin Filho, Nelson (President)
Carlson, Brett Vern
Chamon, Luiz Carlos
Ribas, Roberto Vicencotto
Schelin, Hugo Reuters
Title in Portuguese
"Identificação de mecanismos em reações induzidas por núcleos fracamente ligados"
Keywords in Portuguese
Mecanismos de reação
Núcleos fracamente ligados
Quebra nuclear
Reações nucleares
Abstract in Portuguese
Neste trabalho, a significativa importância dos processos de breakup, fusão incompleta e transferência para o sistema de massa intermediaria 'ANTPOT.6 Li' + 'ANTPOT.59 Co', envolvendo o núcleo estável e fracamente ligado 'ANTPOT.6 Li', é investigada em energias próximas à barreira Coulombiana. Foram realizadas medidas das distribuições angulares das partículas leves nas energias 'E IND.lab' = 18, 22, 26 e 30 MeV, espalhamento elástico nas energias 'E IND.lab' = 12, 18, 22, 26 e 30 MeV e medidas de fusão total (completa+incompleta), por meio do método de espectroscopia 'gama', nas energias 12 MeV < 'E IND.lab' < 26 MeV. As previsões para evaporação do núcleo composto por partículas leves foram baseadas no modelo estatístico, e uma descrição simultânea dos processos de espalhamento elástico, fusão e breakup foi obtida por meio de cálculos de canais acoplados com discretização do contínuo (CDCC). Com base nestes resultados, realizamos a separação das contribuições dos processos de breakup, fusão incompleta e transferência. Por meio de medidas de coincidência entre d e 'alfa', obtivemos as distribuições angulares para o breakup seqüencial do 6Li. Os processos de espalhamento elástico e fusão total do sistema 'ANTPOT.7 Li' + 'ANTPOT.59 Co', e suas descrições sob o formalismo de CDCC também foram estudadas
Title in English
Identification of mechanisms in reactions induced by weakly bound nuclei
Keywords in English
Breakup
Nuclear reactions
Reactions mechanisms
Weakly bound nuclei
Abstract in English
In the present work, the relative importance of breakup, incomplete fusion and transfer processes is investigated in the vicinity of the Coulomb barrier for the intermediate mass target 6Li + 59Co reaction involving the weakly bound 6Li. Measurements for light particle angular distributions were performed at energies Elab = 18, 22, 26 e 30 MeV,elastic scattering at energies Elab = 12, 18, 22, 26 e 30 MeV and total fusion (complete+incomplete), by the -ray spectroscopy method, at energies 12 MeV < Elab < 26 MeV. The compound nucleus decay by light particles was predicted using the statistical model, and a simultaneous description of scattering, fusion and breakup was obtained by means of continuum discretized coupled-channels calculations (Cdcc). Based on these results, the contribution of non-capture breakup, incomplete fusion and transfer were disentangled. The 6Li sequential breakup cross sections were obtained by means of ´alfa´-d coincidence measurements. The Cdcc descriptions of 7Li + 59Co elastic scattering and fusion processes were also subject of study.
 
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Publishing Date
2007-02-01
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • BECK, C, et al. Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets. Nuclear Physics. A , 2010, vol. 834, p. 440-445.
  • SOUZA, F A, et al. Direct measurement of the breakup process. Brazilian Journal of Physics, 2005, vol. 35, nº 3B, p. 888.
  • SOUZA, F A, et al. Reaction mechanisms in the 6Li+59Co system. Nuclear Physics A, 2009, vol. 821, p. 36-50.
  • SOUZA, F A, et al. Study of the effect of the breakup on the fusion cross section of the systems 6,7Li+59Co. Brazilian Journal of Physics, 2004, vol. 34, nº 3A, p. 907.
  • SOUZA, F A, et al. Study of the influence of projectile breakup on the fusion cross section of 6,7Li+12C, 59Co. Progress of Theoretical Physics. Supplement, 2004, nº 154, p. 101.
  • 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 [online], 2010, p. 1.
  • Souza, F.A., et al. 6Li direct breakup lifetimes [doi:10.1016/j.nuclphysa.2010.01.054]. Nuclear Physics. A [online], 2010, vol. 834, p. 420c-423c.
  • SUAIDE, A A P, et al. Dynamics of light heavy-ion reactions in the framework of their time scales. Physics Letters. Section B, 2004, vol. 579, p. 271-277.
  • TOLEDO, A Szanto de, et al. Fusion and breakup in reactions involving weakly bound nuclei. Nuclear Physics A, 2004, vol. 734, p. 311.
  • BECK, C, et al. Near-barrier fusion of weakly bound 6Li and 7Li nuclei with 59Co. Physical Review. C, Nuclear Physics, 2003, vol. 67.
  • SOUZA, F A, et al. Absolute normalization for uncorrelated background with the event mixing technique. Nuclear Instruments & Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment , 2009, vol. 612, p. 196-200.
  • SOUZA, F A, et al. Effect of breakup on elastic scattering for the 6,7Li+59Co systems. Physical Review. C, Nuclear Physics, 2007, vol. 75, p. 044601.
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