The Bernstein Center Freiburg

Informal Seminar
Vahid Mehrpour

University of Tabriz, Iran
Determination of an Optical Potential to Examine Direct Reaction and Fusion Cross Sections Data for the He(6)+Bi(209) System at Near-Coulomb-Barrier Energies
Tuesday, February 9, 2010
14:00 h sharp
Library, first floor
BCCN Building
Hansastr. 9a
The simultaneous chi-square analyses for elastic scattering, direct reaction, and fusion cross sections as a part of our numerical treatment of the optical potential are carried out for two heavy-ion reactions within the framework of an extended optical model that divides a heavy-ion reaction in two direct and fusion reactions. One of these systems is He(6)+Bi(209) in which the used projectile is a halo nucleus, and another is O(16)+Pb(208) in which the projectile is a tightly bounded nucleus. The extended optical potential is determined for these two systems by applying a dispersion relation at near-Coulomb-barrier energies.

As a result of our study both of systems exhibit so-called threshold anomaly in the fusion part of the optical potential. However, the values of the imaginary potential related to the direct reaction has a magnitude much larger than the values of the fusion part of the imaginary potential for the He(6)+Bi(209) system, so that we can not see threshold anomaly in the total imaginary part of the polarization potential. The situation is very different for the O(16)+Pb(208) system, because the fusion part of imaginary potential is dominant and threshold anomaly is observed in the total imaginary part of the optical potential.
The talk is open to the public. Guests are cordially invited!