E.M. Szanto

Reaction mechanisms in the 6Li + 59Co system

Abstract The reactions induced by the weakly bound 6 Li projectile interacting with the intermediate mass target 59 Co were investigated. Light charged particles singles and α – d coincidence measurements were performed at the near barrier energies E lab = 17.4 , 21.5, 25.5 and 29.6 MeV. The main contributions of the different competing mechanisms are discussed. A statistical model analysis, Continuum-Discretized Coupled-Channels (CDCC) calculations and two-body kinematics were used as tools to provide information to disentangle the main components of these mechanisms. A significant contribution of the direct breakup was observed through the difference between the experimental sequential breakup cross section and the CDCC prediction for the non-capture breakup cross section.

Influence of nucleon Fermi motion on incomplete fusion

Abstract Velocity spectra were measured for evaporation residues produced in fusion reactions induced by 5–35 MeV/ A 14 N. The results, together with published data for 16 O and 20 Ne induced fusion, are shown to reveal a projectile dependence of incomplete fusion processes. The data can be qualitatively described in terms of a picture which takes into account the vector addition of the center-of-mass velocities of the interacting nuclei with the intrinsic Fermi velocities of the nucleons.

Fusion and peripheral processes in the 9Be + 10,11B reactions

Abstract Measurements of total fusion cross sections for 9 Be + 10,11 B have been performed over the energy range from 2 to 4.5 times the Coulomb barrier. Elastic scattering and peripheral processes have also been investigated. No significant inhibition of the maximum fusion cross section is observed in spite of the low binding energy of the collision participants.

Reaction mechanisms for weakly-bound, stable nuclei and unstable, halo nuclei on medium-mass targets

An experimental overview of reactions induced by the stable, but weakly-bound nuclei 6Li, 7Li and 9Be, and by the exotic, halo nuclei 6He, 8B, 11Be and 17F on medium-mass targets, such as 58Ni, 59Co or 64Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion processes, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.

Effect of breakup on elastic scattering for theLi6,7+Co59systems

The elastic scattering for the {sup 6,7}Li+{sup 59}Co systems was investigated in the bombarding energy range 12 MeV{<=}E{sub lab}{<=}30 MeV by means of an analysis using the Sao Paulo potential, through which the behavior of the real and imaginary parts as function of the bombarding energy was established. The experimental results suggest that overall there is an evidence of the usual threshold anomaly for both systems, although for the {sup 6}Li+{sup 59}Co system, an evidence of the breakup threshold anomaly could also be questioned.

6Li direct breakup lifetimes

Abstract α − d coincidence data are studied for the 6 Li + 59 Co reaction at E l a b = 29.6 MeV . A kinematic analysis is used to identify which process, leading to the same final state, has the major contribution for selected angular regions. The contributions of the 6 Li sequential and direct breakup to the incomplete fusion/transfer process is discussed by considering the corresponding lifetimes obtained by using a semiclassical approach.

Projectile breakup dynamics for 6Li + 59Co : Kinematical analysis of \alpha - d coincidences

A study of the kinematics of the

Fusion hindrance in light nuclear systems: binding energy and/or surface diffuseness effect?

\alpha

Complete fusion of 9Be + 29Si

-d coincidences in the 6Li + 59Co system at a bombarding energy of Elab = 29.6 MeV is presented. With exclusive measurements performed over different angular intervals it is possible to identify the respective contributions of the sequential and direct projectile breakup components. The angular distributions of both breakup components are fairly well described by the Continuum-Discretized Coupled-Channels framework (CDCC). Furthermore, a careful analysis of these processes using a semiclassical approach provides information on both their lifetime and their distance of occurrence with respect to the target. Breakup to the low-lying (near-threshold) continuum is delayed, and happens at large internuclear distances. This suggests that the influence of the projectile breakup on the complete fusion process can be related essentially to the direct breakup to the 6Li high-lying continuum spectrum.

The Trojan horse method in nuclear astrophysics: Recent results

Abstract Systematic studies of fusion barriers for p and light s – d shell nuclei show an increase of the value of their height as the atomic mass number decreases. Two features are observed to be associated to this effect: the low binding energy of a nucleon or cluster and the increase of the nuclear surface diffuseness. The relative competition of these two features is discussed in the present paper.