Indirect measurement of the 57.7 keV resonance strength for the astrophysical γ -ray source of the Mg25(p,γ)Al26 reaction

Abstract

$^{25}\mathrm{Mg}(p,\ensuremath{\gamma})^{26}\mathrm{Al}$ is the most important reaction in the Mg-Al cycle in the hydrogen burning regions of stars. Its cross sections at stellar energies are essential to understand the issues of radioactive $^{26}\mathrm{Al}$ in the galaxy and meteorites. The 57.7 keV resonance dominate the $^{25}\mathrm{Mg}(p,\ensuremath{\gamma})^{26}\mathrm{Al}$ astrophysical reaction rates at relative low temperature, but it is very difficult to measure its resonance strength directly, and the indirect measurement results deviate by a factor of about 2 by far. In this work, the angular distributions of $^{25}\mathrm{Mg}(^{7}\mathrm{Li},^{6}\mathrm{He})^{26}\mathrm{Al}$ leading to 6.364 MeV and eleven low-lying states in $^{26}\mathrm{Al}$ have been measured by the Q3D magnetic spectrometer of the HI-13 tandem accelerator. The spectroscopic factors were derived and used to deduce the proton width and 57.7 keV resonance strength. The astrophysical $^{25}\mathrm{Mg}(p,\ensuremath{\gamma})^{26}\mathrm{Al}$ reaction rates at stellar energies have been updated by using the present result.