Hindrance of Heavy-Ion Fusion due to Nuclear Incompressibility

We propose a new mechanism to explain the unexpected steep falloff of fusion cross sections at energies far below the Coulomb barrier. The saturation properties of nuclear matter are causing a hindrance to large overlap of the reacting nuclei and consequently a sensitive change of the nuclear potential inside the barrier. We report in this Letter a good agreement with the data of coupled-channels calculation for the ⁶⁴Ni+⁶⁴Ni combination using the double-folding potential with Michigan-3-Yukawa-Reid effective N-N forces supplemented with a repulsive core that reproduces the nuclear incompressibility for total overlap.