254 research outputs found
Continuum-continuum coupling and polarization potentials for weakly bound system
We investigate the influence of couplings among continuum states in
collisions of weakly bound nuclei. For this purpose, we compare cross sections
for complete fusion, breakup and elastic scattering evaluated by continuum
discretized coupled channel (CDCC) calculations, including and not including
these couplings. In our study, we discuss this influence in terms of the
polarization potentials that reproduce the elastic wave function of the coupled
coupled channel method in single channel calculations. We find that the
inclusion of couplings among the continuum states renders the real part of the
polarization potential more repulsive, whereas it leads to weaker apsorption to
the breakup channel. We show that the non-inclusion of continuum-continuum
couplings in CDCC calculations may not lead to qualitative and quantitative
wrong conclusions.Comment: 4 pages, 4 figures. Submitted to Phys. Rev.
Assessing the adequacy of the bare optical potential in near-barrier fusion calculation
We critically examine the differences among the different bare nuclear
interactions used in near-barrier heavy ion fusion analysis and
Coupled-Channels calculations, and discuss the possibility of extracting the
barrier parameters of the bare potential from above-barrier data. We show that
the choice of the bare potential may be critical for the analysis of the fusion
cross sections. We show also that the barrier parameters taken from above
barrier data may be very wrong.Comment: 8 pages, 3 tables, 8 figures. Submitted to Physical Review
Microscopic cluster model for the description of (18O,16O) two-neutron transfer reactions
Excitation energy spectra and absolute cross-section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: The extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections
Microscopic cluster model for the description of new experimental results on the C 13 (O 18, O 16) C 15 two-neutron transfer at 84 MeV incident energy
The C13(O18,O16)C15 reaction is studied at 84 MeV incident energy. Excitation energy spectra and absolute cross-section angular distributions for the strongest transitions are measured with good energy and angular resolutions. Strong selectivity for two-neutron configurations in the states of the residual nucleus is found. The measured cross-section angular distributions are analyzed by exact finite-range coupled reaction channel calculations. The two-particle wave functions are extracted using the extreme cluster and the independent coordinate scheme with shell-model derived coupling strengths. A new approach also is introduced, the microscopic cluster, in which the spectroscopic amplitudes in the center-of-mass reference frame are derived from shell-model calculations using the Moshinsky transformation brackets. This new model is able to describe well the experimental cross section and to highlight cluster configurations in the involved wave functions
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