The current status of astrophysical S*-factor studies for the 12C+12C fusion reaction

Abstract:
Over the past two decades, astronomical observations of superbursts, initiated by the 12C+12C fusion reaction on the surfaces of neutron stars, have remained elusive by theoretical models based on the reaction rate of 12C+12C fusion reaction. Consequently, direct measurements for the cross section of the 12C+12C fusion reaction at energies well below Coulomb barriers have become a hot topic in nuclear astrophysics. For typical superbursts, the Gamow window energy of the 12C+12C fusion reaction is 1.5 ± 0.3 MeV, significantly lower than the Coulomb barrier. This makes it a huge challenge to directly measure the extremely low cross section of the fusion reaction in the corresponding energy region.The experiment by the Trojan Horse Method (THM) is the only measurement providing the excitation functions for all exit channels within the Gamow window. However, the experimental results still remain highly controversial at present. This work reviews the current status of measurement experiments for the 12C+12C fusion reaction and provides a novel interpretation of the data for THM. Combining the theory of identical boson systems, we discuss compound nuclear excited states in 24Mg extracted from THM, and the S* factor for the 12C+12C fusion reaction within the Gamow window. Furthermore, the reduced-width amplitude for the entrance channel of the 12C+12C fusion reaction within the Gamow window is suggested as =0.031.