Potential inversion with subbarrier fusion data revisited

TL;DR

This paper revisits the inversion of heavy-ion fusion data at subbarrier energies to directly determine internucleus potentials, explicitly considering channel couplings, revealing thicker potentials than phenomenological models and discussing their relation to fusion cross section fall-off.

Contribution

It introduces a method to invert fusion data considering channel couplings, providing more accurate internucleus potentials at deep subbarrier energies.

Findings

Inverted potentials are significantly thicker than phenomenological ones.

Channel couplings influence the shape of the internucleus potential.

The results relate to the steep fall-off of fusion cross sections at low energies.

Abstract

We invert experimental data for heavy-ion fusion reactions at energies well below the Coulomb barrier in order to directly determine the internucleus potential between the colliding nuclei. In contrast to the previous applications of the inversion formula, we explicitly take into account the effect of channel couplings on fusion reactions, by assuming that fusion cross sections at deep subbarrier energies are governed by the lowest barrier in the barrier distribution. We apply this procedure to the $^{16}$O +$^{144}$Sm and $^{16}$O +$^{208}$Pb reactions, and find that the inverted internucleus potential are much thicker than phenomenological potentials. A relation to the steep fall-off phenomenon of fusion cross sections recently found at deep subbarrier energies is also discussed.