Exploring fusion at extreme sub barrier energies with weakly bound nuclei

Accepted for publication in Physical Review LettersResults of measurement of residues formed in fusion of 6Li with 198Pt in the energy range of 0.68< E/$V_b$ <1.3 using a new sensitive off-beam technique are reported. The fusion excitation function and the derived average angular momenta do not indicate a change of slope at deep sub-barrier energies, contrary to recent observations. The present results for a system with weakly bound projectile confront the current understanding of the fusion hindrance at these low energies, underlying the role of internal re-organization on the dynamical path towards fusion

Evidence for transfer followed by breakup in 7Li + 65Cu

The observation of a large cross-section for the alpha + d channel compared to breakup into the alpha + t channel from an exclusive measurement for the 7Li+65Cu system at 25 MeV is presented. A detailed analysis of the angular distribution using coupled channels Born approximation calculations has provided clear evidence that the observed alpha + d events arise from a two step process, i.e. direct transfer to the 2.186 MeV (3+) resonance in the alpha + d continuum of 6Li followed by breakup, and are not due to final state interaction effects.Comment: 12 pages, 3 figures, To be published in Phys. Letts.

Transfer vs. Breakup in the interaction of the 7Be Radioactive Ion Beam with a 58Ni target at Coulomb barrier energies

We measured for the first time 7Be elastically scattered nuclei as well as 3,4He reaction products from a 58Ni target at 22.3 MeV beam energy. The data were analyzed within the optical model formalism to extract the total reaction cross section. Extensive kinematical, Distorted Wave Born Approximation (DWBA)and Continuum Discretized Coupled Channel (CDCC) calculations were performed to investigate the 3,4He originating mechanisms and the interplay between different reaction channels

Fusion of 8He with 206Pb around Coulomb barrier energies

The experimental study of the fusion of light neutron-rich nucleus 8He with 206Pb is reported in this work. A fusion stack of 206Pb targets has been used for this study. The most prominent evaporation residue (210Po), which has half-life of 138 days and decays by alpha emission, is populated in the reaction. Radiochemical analysis technique is used to extract the yield of this evaporation residue. © Owned by the authors, published by EDP Sciences, 2011This work was partially supported by the Spanish Ministry of Science and Innovation (MICINN) under projects FPA2007-63074 (FINURA) and INGENIO-2010 (CPAN). It has also been supported by the European Union ”SPIRAL2 preparatory phase” Grant agreement 212692, through the FP7 European programPeer Reviewe

Coupled channel effect in elastic scattering and fusion for 6,7

The fusion excitation and elastic angular distribution were measured for 6,7Li+28Si from below to above Coulomb barrier (≤ 3Vb) energies. The barrier distribution derived from the fusion data was found to be broad and asymmetric at the sub-barrier region, compared to 1D BPM estimation. Effect of rotational coupling on fusion was found to be not so dominant. Phenomenological optical potential parameters, with surface and volume type imaginary potentials, were obtained from f tting of elastic scattering data and energy dependence of real and imaginary surface strengths were investigated around the barrier. CDCC calculations considering only breakup of projectile were performed for 6,7Li+28Si with the elastic scattering data, using the code FRESCO. The effects of breakup of projectile on elastic cross section do not agree with the energy dependence of real and imaginary strength with volume type imaginary potential around the barrier

Coupled channel effect in elastic scattering and fusion for 6,7Li+28Si

The fusion excitation and elastic angular distribution were measured for 6,7Li+28Si from below to above Coulomb barrier (≤ 3Vb) energies. The barrier distribution derived from the fusion data was found to be broad and asymmetric at the sub-barrier region, compared to 1D BPM estimation. Effect of rotational coupling on fusion was found to be not so dominant. Phenomenological optical potential parameters, with surface and volume type imaginary potentials, were obtained from f tting of elastic scattering data and energy dependence of real and imaginary surface strengths were investigated around the barrier. CDCC calculations considering only breakup of projectile were performed for 6,7Li+28Si with the elastic scattering data, using the code FRESCO. The effects of breakup of projectile on elastic cross section do not agree with the energy dependence of real and imaginary strength with volume type imaginary potential around the barrier

Study of fusion in

Excitation functions are measured for complete fusion and transfer reactions of 6Li and 7Li with 197Au at energies around the Coulomb barrier. Coupled channel calculations including the couplings to both target and projectile excited states have been performed and are found to explain the data at energies below the barrier. At above barrier energies the complete fusion cross sections are found to be suppressed compared to the coupled channel calculations for both the systems. A systematic comparison of fusion cross-section for halo nuclei 6,8He and weakly bound stable nuclei 6,7Li on 197Au target is also presented. Large neutron transfer cross-sections are observed for 6,7Li as compared to tightly bound projectiles 12C,16O