Speaker
Description
It has been well known that nuclear collective excitations significantly affect heavy-ion reactions at energies around the Coulomb barrier. A prominent example is the large enhancement of fusion cross sections at subbarrier energies. To account for such enhancement, the coupled-channels approach has been widely employed.
While the coupled-channels approach has been successful in reproducing fusion cross sections at subbarrier energies, recent experimental evidence demonstrates that it significantly overestimates fusion cross sections at deep subbarrier energies. This phenomenon, referred to as fusion hindrance, was first identified in the 60Ni+89Y system. Subsequently similar behaviour has been observed in several other medium-heavy systems, such as 64Ni+64Ni. However, it remains unclear to what extent fusion hindrance occurs in lighter systems, such as 12C+12C, which are of critical importance to nuclear astrophysics.
In this contribution, I will discuss recent developments in physics of heavy-ion fusion reactions at deep subbarrier energies. I will first review recent measurements of fusion cross sections at deep subbarrier energies for medium-light systems, such as 12C+24Mg, conducted by the Legnaro group (Alberto Stefanini and Giovanna Montagnoli, et al.). I will then present our recent reanalysis of fusion cross sections for the 12C+12,13C systems and discuss the presence or absence of the fusion hindrance phenomenon in these systems.