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Recently, a square-integrable discrete basis, obtained performing a simple analytical local scale transformation to the harmonic oscillator basis, has been proposed and successfully applied to study the properties of two-body systems. Here, the method is generalized to study three-body systems. To test the goodness of the formalism and establish its applicability and limitations, the capture reaction rate for the nucleosynthesis of the Borromean nucleus 6He (4He+n+n) is addressed. Results are compared with previous publications and with calculations based on actual three-body continuum wave functions, which can be generated for this simple case. The obtained results encourage the application to other Borromean nuclei of astrophysical interest such as 9Be and 12C, for which actual three-body continuum calculations are very involved. [ABSTRACT FROM AUTHOR]

Abstract: We present an optical model (OM) analysis of the elastic scattering data of the reactions 6He+ 27Al and 6He+ 208Pb at incident energies around the Coulomb barrier. The bare part of the optical potential is constructed microscopically by means of a double folding procedure, using the São Paulo prescription without any renormalization. This bare interaction is supplemented with a Coulomb dipole polarization (CDP) potential, which takes into account the effect of the dipole Coulomb interaction. For this CDP potential, we use an analytical formula derived from the semiclassical theory of Coulomb excitation. The rest of the optical potential is parametrized in terms of Woods–Saxon shapes. In the 6He+ 208Pb case, the analysis confirms the presence of long range components, in agreement with previous works. Four-body Continuum-Discretized Coupled-Channels calculations have been performed in order to better understand the features of the optical potentials found in the OM analysis. This study searches to elucidate some aspects of the optical potential of weakly bound systems, such as the dispersion relation and the long range (attractive and absorptive) mechanisms. [Copyright &y& Elsevier]

Abstract: We present angular distributions of the scattering measured at three bombarding energies above the Coulomb barrier: . The angular distributions have been analysed in terms of three- and four-body Continuum-Discretized Coupled-Channels calculations considering the effect of the 6He breakup. A behaviour in the cross section at large angles has been observed which was reproduced only by the four-body Continuum-Discretized Coupled-Channels calculation. [Copyright &y& Elsevier]

Abstract: The RIBRAS facility (Radioactive Ion Beams in Brasil) is installed in connection with the 8MV Pelletron tandem of the University of São Paulo Physics Institute. It consists of two superconducting solenoids which focalize light radioactive secondary beams of low energy, produced by transfer reactions. Recent experimental results include the elastic scattering and transfer reactions of 6He halo nucleus on 9Be, 27Al, 51V and 120Sn targets. The elastic scattering and transfer of 8Li and 7Be on several targets is also being studied. The transfer reaction 8Li(p,α)5He of astrophysical interest was also studied in the energy range. [Copyright &y& Elsevier]