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Master's Dissertation
DOI
https://doi.org/10.11606/D.43.2009.tde-11052009-111104
Document
Author
Full name
Orli Camargo Junior
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Guimaraes, Valdir (President)
Crema, Edilson
Galetti, Diógenes
Title in Portuguese
Fator-S astrofísico da reação de captura de próton 8Li(p,)9Be através do estudo da reação de transferência elástica 9Be(8Li,9Be)
Keywords in Portuguese
Aceleração de partículas
Astrofísica
Fator-S
Reações nucleares
Taxa de reação
Abstract in Portuguese
Esse trabalho consistiu na determinação do Fator-S astrofísico da reação de captura 8Li(p,)9Be através do estudo da reação de transferência elástica 9Be(8Li,9Be)8Li. O fator espectroscópico do estado ligado 8Li+p=9Be, obtido à partir das medidas da distribuição angular da reação de transferência 9Be(8Li,9Be)8Li, foi utilizado para normalizar a seção de choque da reação de captura 8Li(p,)9Be, e conseqüentemente obter seu Fator-S. As medidas da distribuição angular da reação 9Be(8Li,9Be) foram realizadas no Nuclear Structure Laboratory, que fica localizado na University of Notre Dame no estado de Indiana nos Estados Unidos da América. Para essas medidas utilizamos um feixe primário de 7Li acelerado a uma energia de 30, 0MeV pelo FN Tandem Van der Graaff Accelerator para produzir o feixe de 8Li. O feixe de 8Li foi produzido pelo sistema TWINSOL a uma energia de 27, 7MeV através da reação de troca de nêutron 9Be(7Li,8Li). O sistema de detecção utilizado consistia de detectores de silício montados na forma de telescópios E-E. As seções de choque das distribuições angulares de espalhamento elástico, 9Be(8Li,8Li)9Be, e transferência, 9Be(8Li,9Be)8Li, foram obtidas entre os Ângulos 15o e 50o (no referencial de laboratório). O fator espectroscópico do estado ligado 8Li+p=9Be foi obtido à partir de cálculos de DWBA (Distorted-Wave Born Approximation) utilizando o código FRESCO. O fator espectroscópico obtido para o estado ligado 8Li+p=9Begs foi SF9Begs=1,63(29), e o valor da profundidade do poço do potencial do estado contínuo 8Li+p obtido foi V 8Li+p 0 =40, 13±1, 63MeV. Com esses parâmetros calculamos o Fator-S para a reação de captura 8Li(p,)9Begs. Também calculamos o valor da taxa de reação para a reação de captura 8Li(p,)9Begs e obtivemos o valor de hi = 0, 583+0,1570,135 × 103 cm3mol1s1 para uma temperatura T9=1.
Title in English
Astrophysic S-Factor for the proton capture reaction 8Li(p,)9Be using the study of the elastic transfer reaction 9Be(8Li,9Be)
Keywords in English
Astrophysics
Nuclear Reactions
Particle Acceleration
Reaction rate
S-Factor
Abstract in English
This work consisted on determinating the astrophysical S-Factor for the capture reaction 8Li(p,)9Be using the elastic-transfer reaction 9Be(8Li,9Be)8Li. The spectroscopic factor for the bound state 8Li+p=9Be, obtained by the study of the angular distribution measurements for the transfer reaction 9Be(8Li,9Be)8Li, was used to normalize the capture reaction cross section 8Li(p,)9Be, and than to obtain the S-Factor. The angular distribution measurements for the reaction 9Be(8Li,9Be) was performed at the Nuclear Structure Laboratory at the University of Notre Dame in the state of Indiana, United States of America. For the measurements we used a 7Li primary beam accelerated to an energy of 30.0MeV by the FN Tandem Van der Graaff Accelerator to produce a 8Li. The 8Li beam was produced using the TWINSOL system at an energy of 27.7MeV using the neutron-transfer reaction 9Be(7Li,8Li). For the detection system we used silicon detectors assembled in E-E telescopes. The angular distributions of the cross sections for the elastic scattering reaction, 9Be(8Li,8Li)9Be, and the transfer reaction, 9Be(8Li,9Be)8Li, were measured from 15o to 50o (at laboratory referencial). The spectroscopic factor for the bound state 8Li+p=9Be was obtained from DWBA (Distorted-Wave Born Approximation) calculations using the FRESCO computer code. The spectroscopic factor obtained for the bound state 8Li+p=9Begs was SF9Begs=1.63(29), and the potential depth obtained for the continuum state 8Li+p was V 8Li+p 0 =40.13±1.63MeV. Using these two parameters we calculated the astrophysical S-Factor for the capture reaction 8Li(p,)9Begs. We also calculated the reaction rate for the capture reaction 8Li(p,)9Begs and obtained its value as hi = 0.583+0.157 0.135 × 103 cm3mol1s1 for the T9=1 temperature.
 
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Publishing Date
2009-05-11
 
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