Hydrogen burning of 24, 25, 26Mg in explosive carbon burning

Abstract The absolute resonance strengths of the 24–26 Mg(p, γ ) 25–27 Al reactions have been studied. The absolute values S c.m. =1.03 ± 0.11, 2.3 ± 0.2 and 2.2 ± 0.2 eV for the frequently used standard resonances at E p =823, 434 and 454 keV in the reactions 24–26 Mg(p, γ ) 25–27 Al, respectively, have been determined. In addition, absolute values for use as standards were determined for the 684 keV 25 Mg(p, γ ) 26 Al and 840 and 1966 keV 26 Mg(p, γ ) 27 Al resonances. New relative values were determined for the strengths of the if 25 Mg(p, γ ) 26 Al resonances at if E p = 0.3–1.7 MeV and the 26 Mg(p, γ ) 27 Al resonances at E p = 0.3–2.1 MeV. The resonance energies and total widths obtained in the present work are also given. The branching ratios and angular distributions of the γ-rays used in the absolute strength determinations were obtained in the same set-up as the absolute strength measurement. Using the revised resonance strengths, the astrophysical reaction rates of hydrogen burning of 24–26 Mg in explosive carbon burning in the stellar temperature region of T = (0.1–5.0) × 10 9 K are compared with Hauser-Feshbach calculations. The present reaction rates are also discussed in the frame of the MgAl cycle.