Beyond the Coherent Coupled Channels Description of Nuclear Fusion

Abstract

New measurements of fusion cross sections at deep sub-barrier energies for the reactions 16O+{204,208}Pb show a steep but almost saturated logarithmic slope, unlike 64Ni-induced reactions. Coupled channels calculations cannot simultaneously reproduce these new data and above-barrier cross-sections with the same Woods-Saxon nuclear potential. It is argued that this highlights an inadequacy of the coherent coupled channels approach. It is proposed that a new approach explicitly including gradual decoherence is needed to allow a consistent description of nuclear fusion.

Investigating energy dissipation through nucleon transfer reactions

“…The ground state is seen to be very weakly populated in the products of these reactions, with excited states populated up to tens of MeV even at energies far below the Coulomb barrier. These results support the importance of including dissipative couplings generated by cluster transfer in fusion models, which may prove important to describing the fusion hindrance effects [4,9] that are seen at low energies.…”

“…Fusion cross sections have been seen to fall off much faster with energy than predicted by standard Coupled Channels (CC) approaches to calculate them below a certain threshold [2,3], calling into doubt the efficacy of these models in this regime [4]. An abundance of recent measurements has shown this hindrance effect to be present in a wide variety of systems [5][6][7][8], such that it appears to be a general feature of heavy ion fusion.…”

Microscopic analysis of sub-barrier fusion enhancement in132Sn+40Ca versus132SnOberacker1, Umar2 2013Phys. Rev. C323460View full textAdd to dashboardCite

“…All sub-barrier fusion calculations assume that there exists an ion-ion potential V (R) which depends on the internuclear distance R. Most of the theoretical fusion studies are carried out with the coupled-channels (CC) method [21][22][23][24] in which one uses empirical ion-ion potentials (typically Woods-Saxon potentials, or double-folding potentials with frozen nuclear densities).…”

Microscopic study ofCa40+Ni58,64fusion reactions

“…It would also be interesting to extend the measurement of fusion cross sections at lower energies for these systems in order to better understand the role of transfer reactions on the deep sub-barrier fusion hindrance recently observed [84,85].…”