Nuclear Seminar

Coupled-channels calculations of heavy-ion fusion at extremely sub-barrier energies

Dr. Henning Esbensen
Argonne National Laboratory

Monday, March 24, 2008   4:00 p.m.   NSH 124
(Refreshments served prior to seminar in NSH 124)

The hindrance of heavy-ion fusion at extreme sub-barrier energies is now a well established phenomenon.  One way to characterize it is in terms of the S factor for fusion, which develops a maximum at very low energy.  This has been observed experimentally in many medium-heavy systems.

I will show that the data, ranging in cross sections from 20 nb to 1 b, can be explained fairly well be coupled-channels calculations that are based on a shallow ion-ion potential in the entrance channel.  I will also show that a shallow potential helps explaining the suppression of the measured fusion cross sections at energies far above the Coulomb barrier, which has been observed in comparison to calculations that are based on relatively deep potentials.  The coupled-channels method will also be applied to analyze the ¹⁶O + ¹⁶O fusion data in order to investigate whether the fusion hindrance phenomenon exists in such a light system.