Determination of resonances in Gamow window for 12C+12C fusion reaction via thick-target inverse kinematics method

Abstract

The ¹²C+¹²C fusion reaction at deep subbarrier energies is important for understanding the carbon burning process in massive star and explosive binary systems. However, its reaction rates are very difficult to measure directly or evaluate by simple extrapolation due to the extremely small cross sections and complex resonance structures near the Gamow window. In this work, we use one of its exit channels, i.e. ²³Na+p to populate the excited states of the compound nucleus ²⁴Mg via the conventional thick-target inverse kinematics method. By applying γ-charged particle coincidence, we have obtained excitation functions for the proton and α emission channels, respectively, and derived the resonance parameters through a simultaneous multi-channel R-matrix analysis. It is clear that a series of discrete resonances exist in the most relevant excitation energy region of ²⁴Mg. The astrophysical S-factor of the ¹²C+¹²C fusion reaction is evaluated by adopting a systematic reduced width for the entrance channel. In particular, branching ratios of the dominant four decay channels are estimated across the entire Gamow window of the ¹²C+¹²C fusion reactions. Significant fluctuations are shown that may have strong impacts on the final outcome of the carbon burning process.