Direct Measurements of the $^{23}$Na($\alpha$,p)$^{26}$Mg reaction cross section at energies relevant for the production of galactic $^{26}$Al

ORAL

Abstract

In the convective C/Ne burning shell of massive pre-supernova stars, the $^{23}$Na($\alpha$,p)$^{26}$Mg reaction is one of the main sources of protons for the $^{25}$Mg(p,$\gamma$)$^{26}$Al reaction, which is the primary direct process for $^{26}$Al production in this environment. A recent study found that a factor of 10 increase in the $^{23}$Na($\alpha$,p)$^{26}$Mg reaction rate corresponds to a factor of 3 change in the final abundance of $^{26}$Al for this particular scenario. No reliable experimental information exists at appropriate astrophysical energies. The recommended rate is based on a statistical model. We have performed a direct measurement of the $^{23}$Na($\alpha$,p)$^{26}$Mg reaction cross section using inverse kinematics with a $^{23}$Na beam from ATLAS, a cryogenic $^4$He gas target, and an array of Double Sided Silicon Detectors. Integrated cross sections for the reactions $^{23}$Na($\alpha$,p$_{0}$)$^{26}$Mg and $^{23}$Na($\alpha$,p$_{1}$)$^{26}$Mg$^{*}$ have been extracted for the first time at astrophysically relevant energies(E$_{cm}$ = 1.84 MeV to 2.63 MeV). The corresponding stellar reaction rate has been recalculated and compared with the statistical model recommended rate.

*This work is supported by the U.S. DOE Office of Nuclear Physics DE-AC02-06CH11357

Authors

  • Sergio Almaraz-Calderon

    • Argonne National Laboratory
  • Peter F. Bertone

    • Louisiana State University
  • Martin Alcorta

    • Argonne National Laboratory
  • K. Ernst Rehm

    • Argonne National Laboratory
  • Michael Albers

    • Argonne National Laboratory
  • Catherine M. Deibel

    • Louisiana State University
  • John P. Greene

    • Argonne National Laboratory
  • Dale H. Henderson

    • Argonne National Laboratory
  • Calem R. Hoffman

    • Argonne National Laboratory
  • Scott T. Marley

    • Department of Physics, University of Notre Dame
  • John Rohrer

    • Argonne National Laboratory