Experimental study of the astrophysically important 23 Na(α ,p ) 26 Mg and 23 Na(α ,n ) 26 Al reactions

The $^{23}\\mathrm{Na}(\\ensuremath{\\alpha},p)^{26}\\mathrm{Mg}$ and $^{23}\\mathrm{Na}(\\ensuremath{\\alpha},n)^{26}\\mathrm{Al}$ reactions are important for our understanding of the $^{26}\\mathrm{Al}$ abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using $^{4}\\mathrm{He}$ as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the $^{23}\\mathrm{Na}(\\ensuremath{\\alpha},p)^{26}\\mathrm{Mg}$ and the $^{23}\\mathrm{Na}(\\ensuremath{\\alpha},n)^{26}\\mathrm{Al}$ reactions are in good agreement with previous experiments and with statistical-model calculations. The astrophysical reaction rate of the $^{23}\\mathrm{Na}(\\ensuremath{\\alpha},n)^{26}\\mathrm{Al}$ reaction has been reevaluated and it was found to be larger than the recommended rate.