Recent experimental results in sub- and near-barrier heavy ion fusion reactions (2nd edition)

This article is a new edition of the review published six years ago by the same auhors [Eur. Phys. J. A 54, (2017) 218]. It includes additionally the most recent and significant results obtained in the field of heavy-ion fusion near and below the Coulomb barrier, which have been important for the advance of our knowledge. In particular, we present a selection of recent findings concerning the fusion dynamics of light systems, which is relevant for astrophysics, and moreover recent information obtained from measurements involving heavy-ion exotic beams. With respect to the previous paper, the description of relevant set-ups and methods is done in a dedicated Section. Recent advances obtained in the field of near and sub-barrier heavy-ion fusion reactions are reported. Early data on sub-barrier fusion taught us that cross sections strongly depend on the low-energy collective modes of the colliding nuclei, and on couplings to transfer channels. The coupled-channels model has been successful in the interpretation of the experiments, and fusion barrier distributions may yield the fingerprint of the relevant coupled channels. Far below the barrier, the slope of the excitation function keeps increasing in many cases and standard calculations over-predict the cross sections. This was named a hindrance phenomenon whose physical origin is a matter of debate. Recent theoretical developments suggest that hindrance may be a consequence of the Pauli exclusion principle. Hindrance has far-reaching consequences in astrophysics where the fusion of light systems determines stellar evolution during the carbon and oxygen burning stages.