Oak Ridge National Laboratory

Physics Division

Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,

Alfredo Galindo-Uribarri
Tel (Office): (865) 574-6124  (FAX): (865) 574-1268

Tue., September 30, 2008, at 3:00 p.m. (refreshments at 2:40 p.m.)

Static and Dynamic Effects on Fusion of Halo Nuclei

Paulo R. S. Gomes, Instituto de Física, Universidade Federal Fluminense Niterói, Rio de Janeiro, Brazil
Building 6008, Conference Room

In the last years, an important question has been investigated and not yet fully answered. Is fusion induced by halo nuclei enhanced when compared with the corresponding tightly bound isotope? One might classify two different kinds of effects of the breakup of weakly bund nuclei on the fusion process. 1: Static effects, like the longer the tail of the nuclear potential and the large size of the halo nucleus, leading to a smaller Coulomb barrier – these effects should enhance fusion cross section. 2: Dynamical effects, like the strong coupling between the elastic scattering and continuum states represented by the breakup – that should suppress fusion cross section by taking flux from the elastic channel that otherwise would go to fusion, to other reaction processes – and coupling of soft resonance states – that might enhance fusion cross section. So far, these two effects have not been disentangled, and in this talk we plan to present a way to do so.

Usually one compares data of fusion induced by halo nuclei with theoretical predictions or with fusion data induced by similar tightly bound nuclei. We propose a way to compare different systems in a same plot, valid for energies above and below the Coulomb barrier, and also a universal curve valid for energies above and not too much below the barrier. Following our prescription, we are able to isolate the static effects from the dynamical ones, by using a reliable bare potential. The dynamical effects could then be studied by coupled channel calculations. We will show how this method works for the available fusion cross sections induced by the halo 6He projectile. Some other experiments with stable weakly bound nuclei will be reported.