Speaker
Description
A Bayesian analysis of the modified astrophysical factor S∗(E) for the 12C + 12C fusion reaction is presented using available data at carbon–carbon energies Ecm < 3.5 MeV, including direct measurements, Coulomb-renormalized Trojan Horse Method results, and recent inverse-kinematics data.
The inference is performed for y(E) = log10 S∗(E), represented by a quadratic polynomial in energy with global coefficients determined by Monte Carlo sampling of the weighted χ2 likelihood. All quoted experimental uncertainties are included in the likelihood. To obtain a stable weighted-χ2 analysis of about 600 heterogeneous data points with different normalizations and systematic effects, I added an additional conservative 25% systematic uncertainty. The posterior for y(E) is then propagated to obtain the median smooth S∗(E) curve and its 68% credible band.
Except at the lowest extrapolated energies, the resulting S*(E) is below the estimate of Fowler, Caughlan, and Zimmerman [W. A. Fowler, G. R. Caughlan, and B. A. Zimmerman, Annu. Rev. Astron. Astrophys. 13, 69 (1975)] over most of the considered energy interval. The astrophysical impact is evaluated through the thermonuclear reaction rate NA⟨σv⟩, retaining the measured low-energy resonance structure through the direct inverse-kinematics input. The resulting rate band is noticeably lower than the CF88 analytic rate [G. R. Caughlan and W. A. Fowler, At. Data Nucl. Data Tables 40, 283 (1988)].