We report the first (in)elastic scattering measurement of 25 Al + p with the capability to select and measure in a broad energy range the proton resonances in 26 Si contributing to the 22 Mg(α, p) reaction at type I x-ray burst energies. We measured spin-parities of four resonances above the α threshold of 26 Si that are found to strongly impact the 22 Mg(α, p) rate. The new rate advances a state-ofthe-art model to remarkably reproduce lightcurves of the GS 1826-24 clocked burster with mean deviation <9% and permits us to discover a strong correlation between the He abundance in the accreting envelope of photospheric radius expansion burster and the dominance of 22 Mg(α, p) branch.

Type I X-ray bursts (XRBs) are the most frequently observed thermonuclear explosions in nature. The 22Mg(α,p)25Al reaction plays a critical role in XRB models. However, experimental information is insufficient to deduce a precise 22Mg(α,p)25Al reaction rate for the respective XRB temperature range. A new measurement of 25Al+p resonant scattring was performed up to the astrophysically interested energy region of 22Mg(α,p)25Al. Several resonances were observed in the excitation functions, and their level properties have been determined based on an R-matrix analysis. In particular, proton widths and spin-parities of four natural-parity resonances above the α threshold of 26Si, which can contribute the reaction rate of 22Mg(α,p)25Al, were first experimentally determined.

The 12C+12C fusion reaction plays a crucial role in stellar evolution and explosions. Its main open reaction channels include , p, n, and 8Be. Despite more than a half century of efforts, large differences remain among the experimental data of this reaction measured using various techniques. In this work, we analyze the existing data using a statistical model. Our calculation shows the following: 1) the relative systematic uncertainties of the predicted branching ratios decrease as the predicted ratios increase; 2) the total modified astrophysical S-factors (S * factors) of the p and channels can be obtained by summing the S * factors of their corresponding ground-state transitions and the characteristic rays, while taking into account the contributions of the missing channels to the latter. After applying corrections based on branching ratios predicted by the statistical model, an agreement is achieved among the different data sets at E cm> 4 MeV, while some discrepancies remain at lower energies, suggesting the need for better measurements in the near future. We find that theS * factor recently obtained from an indirect measurement is inconsistent with the direct measurement value at energies below 2.6 MeV. We recommend upper and lower limits for the 12C+12C S * factor based on the existing models. A new 12C+12C reaction rate is also recommended.

The carbon fusion reaction is crucial in stellar evolution. Despite six decades of studies, there is still a large uncertainty in the reaction rate which limits our understanding of various stellar objects, such as massive stars, type Ia supernovae, and superbursts. In this paper, we review the experimental and theoretical studies of the carbon fusion reaction at sub-barrier energies. An outlook for future studies is also presented.