New Measurement of C12+C12 Fusi

Abstract

Carbon and oxygen burning reactions, in particular, 12 C þ 12 C fusion, are important for the understanding and interpretation of the late phases of stellar evolution as well as the ignition and nucleosynthesis in cataclysmic binary systems such as type Ia supernovae and x-ray superbursts. A new measurement of this reaction has been performed at the University of Notre Dame using particle-γ coincidence techniques with SAND (a silicon detector array) at the high-intensity 5U Pelletron accelerator. New results for 12 C þ 12 C fusion at low energies relevant to nuclear astrophysics are reported. They show strong disagreement with a recent measurement using the indirect Trojan Horse method. The impact on the carbon burning process under astrophysical scenarios will be discussed.

The Study of Key Reactions Shaping the Post-Main Sequence Evolution of Massive Stars in Underground Facilities

“…The discrepancy is less evident, but still present, for the alpha channel. In the energy region between 2.5 and 3 MeV, there is some tension between the results of Tan et al (2020) and previous measurements Jiang et al (2018) for both proton and alpha channels. The S-factor results at the center of mass energies above 4 MeV agree nicely with other data.…”

“…The most recent measurement of the 12 C+ 12 C cross-section has been performed by Tan et al (2020) at the University of Notre Dame. The simultaneous detection of protons and alphas, through a silicon detector array, and c-rays with a 109% HPGe detector, allowed for particle-c coincidence technique.…”

Massive Star Modeling and Nucleosynthesis

“…Variations in the 12 C(α, γ ) 16 O rates have an impact on the shell C-burning s-process production as well (El Eid et al, 2004;The et al, 2007;deBoer et al, 2017), because the C/O ratio at the end of He burning determines the future structure of the shell C burning (number and thickness of the shells). During carbon burning, the carbon fusion reaction is also the subject of debate because low-energy resonances are complicated to determine (Gasques et al, 2007;Tumino et al, 2018;Fruet et al, 2020;Tan et al, 2020). Again, by changing the condition of T and ρ at which carbon burning occurs, a variation in the carbon fusion rate modifies the width of the core and subsequent shells and affects the s-process yields (Gasques et al, 2007;Bennett et al, 2012).…”

Fusion dynamics of 12C + 12C reaction: An astrophysical interest within the relativistic mean‐field approach

“…In the process of stellar Helium burning, the main products are 12 C and 16 O. For massive stars, with mass greater than 8 M ⊙ , the Carbon and Oxygen burning reactions, and principally the 12 C + 12 C, plays a significant role in later phases of stellar evolution and explosions (Aguilera et al 2006; Patterson et al 1969; Tan et al 2020). The crucial temperature for such reactions to occur in the stars lies in the range of 0.8–1.2 GK, which corresponds to the center‐of‐mass energies ( E c .…”

“…In addition to this, there are resonant structures observed even at a very low energy region. As a result, large uncertainties persist in reaction rate while extrapolating the data at an astrophysically significant energy range (Beck et al (2020); Tan et al (2020)). So the experimental measurement of the fusion cross‐section for 12 C + 12 C fusion reaction has been limited to the energies above E c .…”