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Doctoral Thesis
DOI
https://doi.org/10.11606/T.43.1998.tde-20022014-145232
Document
Author
Full name
Gilberto Francisco de Lima
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1998
Supervisor
Committee
Lepine, Alinka (President)
Appoloni, Carlos Roberto
Carlson, Brett Vern
Helene, Otaviano Augusto Marcondes
Ribas, Roberto Vicencotto
Title in Portuguese
Medidas de Raios de Núcleos Radioativos Deficientes em Nêutrons com A ~ 60 - 80
Keywords in Portuguese
Física nuclear
Núcleos radioativos
Raios nucleares
Abstract in Portuguese
Foram medidos, através do chamado Método Direto, as seções de choque de interação (sigmaBARRA) e os raios reduzidos de interação (r IND.o) de isótopos deficientes em nêutrons do ANTIND 31 Ga, ANTIND 32 Ge, ANTIND 33 As, ANTIND 34 Se e ANTIND 35 Br; com massa A DA ORDEM DE 60 - 80. O feixe radioativo, incidente em um detetor alvo de Si, foi produzido plea fragmentação de um feixe de ANTPOT 78 Kr, com energia de 73 MeV/núcleon, num alvo de ANTPOT nat Ni, no Laboratório GANIL, França. Verificou-se um suave decréscimo dos valores de r IND.o com o aumento do número de nêutrons N para praticamente todas as cadeias isotópicas, exceto para a do ANTIND 35 Br. Estes resultados não mostraram correlação com deformações, observadas em alguns núcleos desta região. Cálculos teóricos para os raios destes núcleos utilizando-se o modelo de Glauber, baseado em densidades de matéria nuclear obtidas a partir da teoria de Campo Médio Relativístico, apresentaram uma boa concordância com os valores medidos, sem contudo conseguirem reproduzir a tendência decrescente com N experimentalmente observada. São apresentados, também, os resultados de tentativas feitas para viabilizar o estudo de núcleos exóticos no Laboratório Pelletron do IFUSP. Desenvolveu-se o Método Direto para funcionar nas energias disponíveis neste laboratório, e também determinaram-se as providências necessárias para a produção e separação de núcleos radioativos nas condições ali reinantes.
Title in English
Measurements of the radii of neutron-deficient radioactive nuclei with A ~ 60 - 80
Keywords in English
Direct method
Exotic nuclei
Nuclear radii
Radioactive nuclei
Total cross-section
Abstract in English
The interaction cross section sigmaBARRAIND.R and the reduced interaction radii r IND.0 of neutron-deficient, radioactive ANTIND.31 Ga, ANTIND.32 Ge, ANTIND.33 As, ANTIND.34 Se and ANTIND.35 Br isotopes with A DA ORDEM DE 60 80 were measured. The secondary radioactive beam, hitting a Si target/detector system, was produced by the fragmentation of ANTPOT.78 Kr, with 73 MeV/nucleon energy on a ANTPOT.nat Ni target, at the GANIL Laboratory in France. Most elements show reduced radii which decrease slowly with N, with the exception of ANTIND.35 Br. No clear correlations is found between deformation and r IND.0, as observed for charge radii of Kr and Sr. theoretical values of r IND.0 were calculated from Glauber reaction cross-section, based on proton and neutron densities calculated in the Relativistic Mean Field framework. The agreement between theoretical r IND.0 and the data is reasonable, however the decreasing tendency with N is not reproduced. We also present our efforts to produce radioactive beams at Pelletron Laboratory of IFUSP. The Direct Method was implemented at the energies available at Pelletron Laboratory and the problem of the conditions to produce and separate radioactive beams was also addressed.
 
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Publishing Date
2014-02-20
 
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