N. Carlin

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.

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.

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

Light heavy-ion reactions: time scales and emission order of light products

alpha

The Trojan horse method in nuclear astrophysics: Recent results

-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.

A triple telescope for the simultaneous identification of light and heavy reaction products

Abstract Time scales, emission orders and the corresponding fractions of light products from the light heavy-ion reactions 16O+10B (Elab=62.5xa0MeV) and 16O+12C (Elab=64.0xa0MeV), have been determined through the utilization of a technique based on the analysis of the experimental small-angle particle–particle correlations and velocity difference spectra. A three-body trajectory Monte Carlo simulation code was used to fit the data and provide the quantities of interest. For the case of compound nucleus decay, the results are consistent with predictions from the standard statistical model and show that the technique could also be used for the determination of fission time scales.

A LARGE AREA TWO-DIMENSIONAL POSITION SENSITIVE MULTIWIRE PROPORTIONAL DETECTOR

Difficulties in cross-section measurements at very low energies, when charged particles are involved, led to the development of some indirect methods. The Trojan horse method (THM) allows us to bypass the Coulomb effects and has been successfully applied to several reactions of astrophysical interest. A brief review of the THM applications is reported together with some of the most recent results.

Study of 9Be + 12C elastic scattering at energies near the Coulomb barrier

Abstract Sixteen triple telescopes were developed to be used in the study of light heavy-ion nuclear reactions at the University of Sao Paulo Pelletron Laboratory, with the purpose of providing simultaneous identification of light and heavy reaction products. Each telescope consists of one ionization chamber, one Si detector and one CsI detector with photodiode readout. The telescopes are encapsulated in such a way that they can be utilized in different setup geometries depending on the kind of experiment being performed. Results for the ionization chambers energy loss resolution, Si and CsI detectors energy resolution and general performance are presented.

Study of the influence of projectile breakup on the fusion cross section of 6,7Li + 12C, 59Co

Abstract Large area two-dimensional position sensitive multiwire proportional detectors were developed to be used in the study of light heavy-ion nuclear reactions at the University of Sao Paulo Pelletron Laboratory. Each detector has a 20×20xa0cm2 active area and consists of three grids (X-position, anode and Y-position) made of 25xa0μm diameter gold plated tungsten wires. The position is determined through resistive divider chains. Results for position resolution, linearity and efficiency as a function of energy and position for different elements are reported.