[en] Time scales of strongly energy damped and fast processes in light heavy-ion reactions were measured in order to investigate the dynamics involved in the collision. Particle-particle correlation functions at small relative momenta were measured to determine the time scale of sequential particle emission in highly excited light composite systems and the values obtained are compared to the lifetime of the compound nucleus determined by cross section fluctuations measurements. The results indicate that in the case of light nuclear systems, a drastic time scale compression is observed, independent of the inelasticity of the process, in contrast to the case of heavy systems for which the time difference between the fast and slow processes is at least 100-1000 times larger

[en] 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

[en] The investigation of the ^6,7Li + ¹²C, ⁵⁹Co breakup processes (bu) is used to understand the influence of (bu) on the fusion cross section. These measurements help to establish the effect of the projectile breakup on the fusion process at near-barrier energies and contribute to the determination of how the mass of the target affects the process, as well as the influence of the incomplete fusion yield at energies above the barrier. The identification of the breakup products has been achieved measuring the three body final state correlations. Coincidence data are used to determine the process Q-value in order to gate exclusively on the projectile breakup channel. Angular correlations are obtained to identify the several processes. This is complemented by measurements of relative energy of the fragments using different rest frame references (target, projectile, target + fragment) in order to disentangle the contribution of breakup, incomplete fusion and/or transfer-reemission process. These experimental results are compared to three body kinematics calculations. (author)

[en] Time scales, emission orders and the corresponding fractions of light products from the light heavy-ion reactions ¹⁶O+¹⁰B (E_lab=62.5 MeV) and ¹⁶O+¹²C (E_lab=64.0 MeV), 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

[en] The effect of breakup in the fusion cross section in terms of suppression versus enhancement, discussed in a conflicting way in the literature, is addressed. Data and theoretical predictions available in the literature are compared. Excitation functions of the sub- and near-barrier fusion cross-sections for a wide variety of light and heavy systems are presented and interpreted. We have measured fusion excitation functions and breakup correlation functions for the medium weight systems ⁶ Li + ⁵⁹ Co and ⁷ Li + ⁵⁹ Co. These measurements help to establish the influence of the projectile breakup on the fusion process at near-barrier energies and contribute to the determination of how the mass of the target affects the breakup role. The results indicate a light fusion enhancement at sub-barrier energies and a geometry dominated cross section at barrier energies. (author)

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[en] Excitation functions for sub- and near-barrier total (complete + incomplete) fusion cross sections were studied for the ^6,7Li + ⁵⁹Co reactions using standard γ-ray techniques and the results indicate a small enhancement of total fusion cross section at sub-barrier energies for the more weakly bound ⁶Li projectile, with similar cross sections for both reactions at and above the barrier. In order to better understand the breakup contribution to fusion, we performed light particle coincidence measurements for the systems ^6,7Li + ¹²C, ⁵⁹Co at energies near and above the barrier. A three body kinematics analysis is performed with the objective of separating the contributions of different reaction mechanisms. For small angular differences between the light particles, the sequential and direct breakup seem to dominate. On the other hand, for large detector separations, a sequential decay following transfer is likely to dominate. (author)

No abstract available

[en] Full text: The ⁹Be projectile breakup (⁹Be → ⁸Be+n → α+ α + n) has been investigated for ⁹Be+¹²C reaction at a bombarding energy E_Lab = 21 MeV. The ⁸Be energy spectra were reconstructed using α + α coincidence measurements. A preliminary analysis of these spectra suggests that for the high energy region the main contribution is due to neutron transfer to the ¹²C target, and the low energy region of the spectrum can be attributed to the ⁹Be non-capture breakup process. We also measured elastic scattering angular distributions at energies around the Coulomb barrier (E_Lab = 13.0, 14.5, 17.3, 19.0 and 21.0 MeV) in order to check the possible occurrence of a threshold anomaly in the optical potential. The data were analyzed in the framework of the Sao Paulo potential and, within the experimental uncertainties, the existence of this threshold anomaly could not be confirmed. The experimental elastic scattering angular distributions were well described by the optical potential at forward angles for all measured energies. However, for the three highest energies, an enhancement was observed for intermediate and backward angles. This could be explained by the elastic transfer mechanism. (author)