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Habilitation Thesis
DOI
10.11606/T.43.2015.tde-10092015-113726
Document
Author
Full name
Nelson Carlin Filho
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1999
Committee
Vanin, Vito Roberto (President)
Faria, Nelson Velho de Castro
Gomes, Paulo Roberto Silveira
Ribas, Roberto
Silveira, Enio Frota da
Title in Portuguese
Escalas temporais para reações entre íons-pesados leves
Keywords in Portuguese
Física nuclear
Íons pesados
Abstract in Portuguese
Com o objetivo de contribuir para um melhor entendimento da dinãmica de reações nucleares, foram determinadas escalas temporais para sistemas envolvendo íons-pesados leves, através de duas técnicas distintas (flutuações estatísticas e correlações a pequenos momentos relativos), sensiveis a diferentes estágios de evolução temporal. Para a técnica de flutuações estatísticas, foram realizadas medidas de seções de choque para processos onde ocorre a emissão binária de fragmentos complexos, utilizando técnicas de coincidência cinemática, para o sistema ’ANTPOT.16 O’ + ’ANTPOT.10 B’ no intervalo de 22 MeV ’
Title in English
Timescales for reactions between light-heavy ions
Keywords in English
Heavy ions
Nuclear physics
Abstract in English
8inary decay cross seclion measuremenls have been performed for lhe syslems 160 + 108 al 22 MeV _:: Ec.M _:: 24.5 MeV (iSEc.M - 20 keV) and 17 MeV .<::.Ec.M .::_25 MeV (iSEcM - 190 keV ) and for lhe syslem 19F + 12C al 22 MeV .::_Ec.M .<:_24.5 MeV (iSEc.M - 20 keV). The binary fragmenls were identified by lhe kinematic coincidence technique. The excitation functions for these systems show strong fluctuations and their average widths were obtained through the analysis of energy correlation functions. The small widths observed for lhe 160 + 108 (about 20 keV) and 19F + 12C (about 40 keV) systems, correspond to an intermediate system time scale o f about 2 x 1 o·20 s which is larger than its revolution time. These features suggest lhe presence of lhe fusion-fission mechanism. For lhe 160 + 108 system, larger widths (aboul 350 keV) were also observed which are related to a faster process. These aspects are expected for a process where the time scale is comparable to lhe intermediate system revolution time, like an orbiting mechanism. Theoretical predictions for fusion-fission and orbiting mechanisms were compared to lhe experimental results and a good agreement was observed.
 
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1999CarlinFilho.pdf (7.82 Mbytes)
Publishing Date
2015-09-14
 
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