Signature of smooth transition from diabatic to adiabatic states in heavy-ion fusion reactions at deep subbarrier energies

TL;DR

This paper introduces an extended coupled-channels model that smoothly transitions between diabatic and adiabatic states to better explain fusion cross sections at deep subbarrier energies in heavy-ion reactions.

Contribution

The authors develop a novel extension of the coupled-channels framework that simulates a gradual transition from diabatic to adiabatic states by damping off-diagonal couplings.

Findings

Model accurately reproduces steep falloff of fusion cross sections.

Effective in describing reactions like $^{16}$O+$^{208}$Pb, $^{64}$Ni+$^{64}$Ni, and $^{58}$Ni+$^{58}$Ni.

Provides insight into the transition mechanism in heavy-ion fusion at low energies.

Abstract

We propose a novel extension of the standard coupled-channels framework for heavy-ion reactions in order to analyze fusion reactions at deep subbarrier incident energies. This extension simulates a smooth transition between the diabatic two-body and the adiabatic one-body states. To this end, we damp gradually the off-diagonal part of the coupling potential, for which the position of the onset of the damping varies for each eigen channel. We show that this model accounts well for the steep falloff of the fusion cross sections for the $^{16}$O+$^{208}$Pb, $^{64}$Ni+$^{64}$Ni, and $^{58}$Ni+$^{58}$Ni reactions.