The isovector imaginary neutron potential and its impact on the r-process nucleosynthesis

The need for nuclear data far from the valley of stability, for applications such as nuclear astrophysics or future nuclear facilities, challenges the robustness as well as the predictive power of present nuclear models. The isovector contribution to the imaginary component of the microscopic optical model potential remains unconstrained at keV energies. Within the Brückner–Hartree–Fock approximation of Jeukenne-Lejeune-Mahaux, it is shown that experimental neutron strength function data favours a strong isovector component that can have a drastic impact on the radiative neutron capture cross section for neutron-rich nuclei. If confirmed, this result strongly inhibits the neutron capture by exotic nuclei, so that the traditional r-process picture of fast neutron captures during the nucleosynthesis r-process needs to be revisited in depth. Reliable microscopically founded calculations of the optical potential are needed to better understand the neutron capture by exotic nuclei.