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The effect of continuum couplings in the fusion of the halo nucleus 11 Be on 208 Pb around the Coulomb barrier is studied using a three-body model within a coupled discretised continuum channels (CDCC) formalism. We investigate in particular the role of continuum-continuum couplings. These are found to hinder total, complete and incomplete fusion processes. Couplings to the projectile 1p 1/2 bound excited state redistribute the complete and incomplete fusion cross sections, but the total fusion cross section remains nearly constant. Results show that continuum-continuum couplings enhance the irreversibility of breakup and reduce the flux that penetrates the Coulomb barrier. Converged total fusion cross sections agree with the experimental ones for energies around the Coulomb barrier, but underestimate those for energies well above the Coulomb barrier.Introduction: The existence and the role of the breakup process of weakly bound projectiles in complete fusion and scattering mechanisms have been extensively investigated in recent years both theoretically [1-6] and experimentally [7][8][9][10][11][12][13][14][15][16], but there is not yet any definitive conclusion. There are contradictory theoretical works which predict either the suppression [1][2][3][4] or the enhancement [5] of the complete fusion cross section due to the coupling of the relative motion of the nuclei to the breakup channel.Recent coupled channels calculations for 11 Be+ 208 Pb [6] have shown that the coupling of the relative motion to the breakup channel has two effects, depending on the value of the bombarding energy, namely (i) a reduction of the complete fusion cross sections at energies above the Coulomb barrier due to the loss of incident flux, and (ii) an enhancement of the complete fusion cross sections at energies below the Coulomb barrier due to the dynamical renormalisation of the nucleus-nucleus potential. Using the isocentrifugal approximation and an incoming boundary condition inside the barrier, this calculation did not include the effect of the projectile's halo structure on the monopole projectile-target potential. Nor did it include the excitation to partial waves other than p 3/2 in the continuum, or the continuumcontinuum and bound excited states couplings in either reaction partner. Moreover, only a small interval of energy for continuum states (up to 2 MeV) was considered.The couplings between continuum states have been shown to be crucial to understand the breakup of 8 B on a 58 Ni target at low energy E lab = 25.8 MeV [19,20]. Therefore, it could be expected that continuum-continuum couplings significantly affect the role of breakup process in fusion of halo nuclei around the Coulomb barrier. We believe that

Describing the processes in stars which produce the chemical elements for planets and life, this book shows how similar processes may be reproduced in laboratories using exotic beams, and how these results can be analyzed. Beginning with one-channel scattering theory, the book builds up to multi-channel reactions. Emphasis is placed on using transfer and breakup reactions to probe structure and predict capture processes, as well as R-matrix methods for modeling compound nucleus dynamics described by Hauser-Feshbach methods. Practical applications are prominent in this book, confronting theory predictions with data throughout. The associated reaction program Fresco is described, allowing readers to apply the methods to practical cases. Each chapter ends with exercises so readers can test their understanding of the materials covered. Supplementary materials at www.cambridge.org/9780521856355 include the Fresco program, input and output files for the examples given in the book, and hints and graphs related to the exercises.

We discuss calculations of three-body observables for the breakup of 8 B on a 58 Ni target at low energy using the coupled discretised continuum channels approach. Calculations of both the angular distribution of the 7 Be fragments and their energy distributions are compared with those measured at several laboratory angles. In these observables there is interference between the breakup amplitudes from different spin-parity excitations of the projectile. The resulting angle and the energy distributions reveal the importance of the higher-order continuum state couplings for an understanding of the measurements.

Nuclear reaction cross sections are important for a variety of applications in the areas of astrophysics, nuclear energy, and national security. When these cross sections cannot be measured directly or predicted reliably, it becomes necessary to develop indirect methods for determining the relevant reaction rates. The surrogate nuclear reactions approach is such an indirect method. First used in the 1970s for estimating ðn; fÞ cross sections, the method has recently been recognized as a potentially powerful tool for a wide range of applications that involve compound-nuclear reactions. The method is expected to become an important focus of inverse-kinematics experiments at rareisotope facilities. The present paper reviews the current status of the surrogate approach. Experimental techniques employed and theoretical descriptions of the reaction mechanisms involved are presented and representative cross section measurements are discussed.

Total (complete + incomplete) fusion excitation functions of 6,7 Li on 59 Co and 209 Bi targets around the Coulomb barrier are obtained using a new continuum discretized coupled channel (CDCC) method of calculating fusion. The relative importance of breakup and bound-state structure effects on total fusion is particularly investigated. The effect of breakup on fusion can be observed in the total fusion excitation function. The breakup enhances the total fusion at energies just around the barrier, whereas it hardly affects the total fusion at energies well above the barrier. The difference between the experimental total fusion cross sections for 6,7 Li on 59 Co is notably caused by breakup, but this is not the case for the 209 Bi target.