FUSION OF HEAVY IONS AT EXTREME SUB-BARRIER ENERGIES

After shortly reviewing some essential facts related to the sub-barrier fusion like the problem of the inner part of the Coulomb barrier, enhancement of fusion cross sections due to coupling to excited channels, the far-bellow the barrier data relevant for nuclear reactions in stars, we present calculations performed for the cases Ni-58+Ni-58, Ni-64+Ni-64, Ni-64+Ge-74 and Ni-64+Mo-100 where we were able to confirm the steep falloff of the cross sections. Along with the cross sections we present a diagnosis of the deep sub-barrier fusion using specific tools such as the S-factor and the logarithmic derivative L.