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Doctoral Thesis
DOI
10.11606/T.43.2015.tde-06052015-053049
Document
Author
Full name
Vinicius Antonio Bocaline Zagatto
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2015
Supervisor
Committee
Oliveira, Jose Roberto Brandao de (President)
Arazi, Andrés
Chamon, Luiz Carlos
Gomes, Paulo Roberto Silveira
Lichtenthaler Filho, Rubens
Title in Portuguese
Estudo de mecanismos de reação nuclear no sistema 7Li+120Sn utilizando coincidências -partícula
Keywords in Portuguese
Coincidência gamma-partícula
Espalhamento inelástico
Fator espectroscópico
Reação nuclear
Abstract in Portuguese
Medidas em coincidência gamma-partícula da reação 7Li+120Sn foram realizadas na faixa de energia de 2.6 a 3.9 MeV por nucleon. Além do canal inelástico, foram observados os canais de pick-up de próton e stripping de um e dois nêutrons, sendo que, para o último caso, cálculos teóricos de DWBA e CRC comparados com o canal elástico demonstram que esta transferência ocorre de maneira sequencial (two-step) e não direta. Este trabalho consolida a existência de canais já anteriormente observados (pick-up de próton e stripping de um nêutron) além de observar pela primeira vez a existência do canal de strippinp de dois nêutrons, no entanto, ele tem um caráter pioneiro pois é o primeiro a medir distribuições angulares de todos esses canais. Tanto o pick-up de próton quanto o stripping de dois nêutrons tiveram de levar em conta na análise cálculos de Monte Carlo que simulassem o efeito da quebra dos projéteis 8Be e 5Li, respectivamente. Fatores espectroscópicos para alguns estados desses canais foram obtidos e são condizentes com os valores esperados considerando o modelo de single particle e a indistinguibilidade de partículas nos casos dos núcleos 119In e 122Sn. Por outro lado, são muito pequenos (ordem de 10e-2) para estados do 121Sn, fato esse gerado pela provável falta de acoplamento de mais canais de reação que reduzem o fluxo da transferência de nêutron. Foram observados também núcleos gerados a partir da transferência seguida de emissão de partículas.
Title in English
studies on nuclear reactions mechanisms in the system 7Li+120Sn using gamma-particle coincidences
Keywords in English
gamma-particle coincidence
inelastic scattering
Nuclear reactions
spectroscopic factor
Abstract in English
$\gamma$-particle coincidence measurements of the $^7$Li$+^{120}$Sn reaction were made in the $2.6$ to $3.9$ MeV/nucleon energy range. Besides the inelastic channel, the proton {\it pick-up} and one/two neutron {\it stripping} were observed, whereas, for the last case, DWBA and CRC calculations were compared to experimental elastic scattering data and demonstrated that this transfer occurs in a sequential ({\it two-step}) rather than a direct way. This work consolidates the existence of some channels that have already been observed (proton {\it pick-up} and neutron {\it stripping}) and also observes for the first time the existence of the two neutron {\it stripping} channel, however, it still retains its pioneering as it is the first one to measure the angular distributions for all these channels. The proton {\it pick-up} and the two neutron {\it stripping} channels had to take into account in their analysis Monte Carlo calculations to simulate the projectile breaking effect ($^8$Be and $^5$Li, respectively). Spectroscopic factors for some states of these channels were found and are consistent with the expected values considering the {\it single particle} model and the particle indistinguishability for the $^{119}$In and $^{122}$Sn cases, however, these factors are too small (magnitude order of $10^{-2}$) for the $^{121}$Sn case. This was generated most likely by the lack of coupling of some of the reaction channels that would reduce the one neutron transfer flux. Nuclei generated by the transfer followed by particle emission were also observed.
 
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Publishing Date
2015-05-06
 
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