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Doctoral Thesis
DOI
10.11606/T.43.1998.tde-27022014-150737
Document
Author
Full name
Alejandro Javier Dimarco
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1998
Supervisor
Committee
Dias, Helio (President)
Chiapparini, Marcelo
Cruz, Manoel Tiago Freitas da
Duarte, Sérgio José Barbosa
Horvath, Jorge Ernesto
Title in Portuguese
O Papel da Estrutura Nuclear nas Taxas de Decaimento Beta e Captura de Elétrons na Pré-Supernova
Keywords in Portuguese
Estrutura nuclear
Física nuclear
Abstract in Portuguese
Neste trabalho calculamos taxas de captura de elétrons e decaimento beta no estágio de pré-supernova, para espécies nucleares da camada fp que são fundamentais nessa etapa da evolução estelar. Enfatizamos as transições entre estados de baixa energia. No cálculo dos elementos de matriz nucleares foram utilizados modelos microscópicos. Dados experimentais e densidades de níveis foram empregados na construção da função de partição nuclear. Foi avaliado o impacto de nossos cálculos nas abundâncias isotópicas e na derivada temporal da fração de elétrons, comparando o nossos resultados com cálculos mais simples. Concluímos de nosso trabalho que um cálculo mais detalhado das taxas de captura de elétrons e decaimento beta dando ênfase nas transições entre ~estados de baixa energia, pode conduzir a variações importantes nas predições sobre o posterior colapso e explosão da supernova.
Title in English
Role Nuclear Structure Rates Beta Decay Electron Capture Pre-supernova
Keywords in English
Nuclear physics
Nuclear structure
Abstract in English
ln this work we carry out calculations of electron capture and beta decay rates, at presupernova stages, from several nuclei of the fp region that are important in this stages of stellar evolution. We emphasize transitions between low energy states. The nuclear matrix elements was calculated using microscopic models. We used experimental data and level densities in the construction of the nuclear partition function. We estimated the influence of ours calculations in the isotopic abundances and in the temporal variation of the electron fraction. We compared ours results with nives calculations. We conclude that a more detailed calculation of the electron capture and beta decay rates giving emphasize to the transition between low energy states can lead importants variations to predictions about the subsequent collapse and supernova explosion.
 
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45438Dimarco.pdf (51.20 Mbytes)
Publishing Date
2014-02-28
 
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