DASSO , Carlos Hugo

Recent progress in experimental techniques have made possible accurate measurements of fusion cross sections far below the Coulomb barrier, revealing an unexpected behavior of these quantities as a function of the bombarding energy. Besides providing a plausible cause for the observed energy dependence we profit from the nature of...

We exploit a model describing the break-up of weakly-bound nuclei that can be used as a laboratory for testing different prescriptions that have been advanced in the literature to take into account the near-by presence of continuum states. In the model we follow the evolution of a single particle wave function in one dimension, initially bound...

We exploit a model describing the breakup of weakly bound nuclei that can be used as a laboratory for testing different prescriptions that have been advanced in the literature to take into account the nearby presence of continuum states. In the model, we follow the evolution of a single-particle wave function in one dimension, initially bound...

The conclusions extracted from a recent study of the excitation of giant dipole resonances in nuclei at relativistic bombarding energies open the way for a further simplification of the problem. It consists in the elimination of the relativistic scalar and vector electromagnetic potentials and the familiar numerical difficulties associated with...

We investigate alternatives to the standard formalism used for the study of relativistic Coulomb excitation of the giant dipole resonance in nuclei. The idea is to obtain reasonable results for the probabilities of excitation and cross sections to the one-phonon and two-phonon levels avoiding the substantial complexity of the treatments...

The implementation of a number-conserving formalism for pair-addition and pair-removal modes has impaired the possibility of developing an intuitive and self-consistent picture for collective pairing modes. In this paper, we show how a relaxation of this constraint leads to a unified model with true predictive powe

The direct transfer of four nucleons in reactions with superfluid systems is compared with the feeding of the same final channel by a successive transfer of correlated nucleon pairs. A quantitative analysis is carried out for the reaction 120Sn+112Sn which shows the overwhelming dominance of the direct multiparticle transfer at bombarding...

The semiclassical approach has proven to be a most valuable tool for the construction of the scattering matrix and accurate evaluation of cross sections in a large variety of heavy-ion collision problems. In its familiar implementation, however, its use is restricted to what is now known as the "regular regime", as it makes use of classical...

We investigate the effects of nuclear absorption on the population of intrinsic vibrational states in scattering processes involving heavy ions. It is found that at the classical level the removal of flux assumes a qualitatively different form in the regular or chaotic regimes. Specifically, it is shown how certain reaction channels turn out to...

Qualitative arguments are used to estiamte the ratio of excitation energies between heavy and light fragments for asymmetric heavy-ion collisions. The value of this quantity is linked to the relative role played by inelastic and transfer degrees of freedom and thereby to an approximate function of the total kinetic energy loss. A numerical...

The construction of differential cross sections as a function of excitation energy for systems with a collection of low- and high-lying intrinsic vibrational modes has been attempted in the past. A prescription is proposed here that simplifies the implementation of such calculation schemes with a remarkable reduction in computational time.

We exploit analytic properties of the optical potential for elastic scattering of α particles on nuclei to extract information on the effective interaction that should be used to describe the motion of a cluster of two neutrons and two protons bound to a nuclear system. This prescription solves long-standing ambiguities in the formalisms used...

Nuclear dissociation cross sections for halo nuclei have been assumed by various authors to have a A 1/3 dependence on the target mass. These cross sections have also been considered to be a sum of the nuclear and Coulomb components. Explicit calculations of the break-up of 19C induced by various targets show that both of the above assumptions...

The semiclassical approach is one of the fundamental tools used to investigate and analyze heavy ion reaction processes. We show in this contribution that the evolution of the motion that emerges from the knowledge of the semiclassical amplitudes for the reaction channels as a function of time cannot be taken as a reliable representation for an...

We investigate in the framework of the semiclassical approximation the relative importance onf the Coulomb and nuclear fields to induce the break-up of neutron rich nuclei such as LI at energies close to the Coulomb barrier. We assume that the mechanism that leads to the separation is the excitation of a low-lying dipole mode in wich the...

Quadrupole moments and E2 transitions in the O(6) limit of the interacting boson model are studied within a formalism based on the intrinsic frame. We show that the values of these quantities for both ground- and β-bands can be directly obtained, to higher order in N, by suitably projecting the corresponding matrix elements associated with the...