Reaction Mechanisms on the 16,18O + 63,65Cu Systems / Mecanismos de Reação nos Sistemas 16,18O + 63,65Cu

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The quasi-elastic excitation functions for the systems 16,18O + 63,65Cu have been measured, at the angle 161º and at energies between 30 and 48MeV, in the laboratory reference system. The quasi-elastic term refers to the sum of the elastic scattering, the inelastic scattering and the transfer reactions. Care has been taken in order to obtain high precision data in small energy steps of 0,5MeV, because the aim of this work was to perform mathematics operations (derivates)on the experimental points, to deduce the quasi-elastic barrier distributions of these systems. The choice of this angle of detection, the largest possible, allows the direct study of the competition between the fusion and the direct processes, as both are fed by the same partial waves. The energy interval has been chosen to cover the region around the Coulomb barrier, where the barrier distributions constitute a good instrument for the study of the reaction mechanisms at these energies. Beyond the inclusive quasi-elastic, measurements of some transfer channels, at the same angle and energies mentioned above, were possible due to the charge resolution of the detector. The theoretical analysis of the data has been done on the scope of the coupled reaction channel model, with the code FRESCO. Another aim of this work was the utilization of odd-mass nuclei as targets, as their non-vanishing spins introduce additional phenomena to the reaction mechanisms, that might, eventually, be detected by the barrier distributions. A new calculation procedure has been used by the elimination of any imaginary potential at the interaction region, and its substitution by the inclusion of the largest number as possible of channels at the coupled reaction channel calculation. Another important feature of the theoretical analysis is the utilization of many data available in the literature for these systems at energies around the barrier. Thus, the theoretical forecast could be compared with a great set of data and earned consistency and amplitude. The results obtained with this analysis revealed a strong collective behaviour of the 63Cu and 65Cu nuclei, and the first three quadrupolar vibrational states 1/2-, 5/2- and 7/2- prevail over the other excited states. The transfer reactions have small effect over the others processes, but are greatly influenced by them. There is an exception, the two neutron transfer from 18O to 63Cu, whose importance on this system is considerable. Besides, it was revealed that even on these medium weight systems, the ground state reorientation mechanism, of both targets, have large effect on all the analysed nuclear processes, but is strongest on the elastic scattering at back angles. Finally, the quasi-elastic barriers distributions showed up to be sensible to all of these reaction mechanisms and constitute an excellent tool for the study of nuclear reactions.

ASSUNTO(S)

nuclear physics física nuclear reações nucleares nuclear fusion nuclear reactions fusão nuclear

ACESSO AO ARTIGO

Documentos Relacionados