Limits on the direct capture component of the <sup>23</sup>Na(p, γ)<sup>24</sup>Mg reaction
ORAL
Abstract
The 23Na(p,γ)24Mg reaction plays an important role in the nucleosynthesis of elements in the hot bottom
burning environment of asymptotic giant branch stars by providing a breakout path from the NeNa to the
MgAl cycle. At temperatures above ≈0.1 GK, the underlying nuclear reaction contributions to the rate
are primarily narrow resonances, but at lower temperatures direct and broad resonance tail contributions
come to dominate. While there have been recent studies to improve the uncertainties of the contributions
of these narrow resonances, little attention has been paid to the non-resonant component of the capture
cross section. In this work, experimental measurements are reported over the energy range from 0.5
and 1.05 MeV proton beam energy. Several transitions were measured where two broad resonances were
clearly observed whose low energy tails contribute strongly to the low-energy, non-resonant, cross section.
In addition, direct capture in the23Na(p,γ)24Mg reaction was observed for the first time.
burning environment of asymptotic giant branch stars by providing a breakout path from the NeNa to the
MgAl cycle. At temperatures above ≈0.1 GK, the underlying nuclear reaction contributions to the rate
are primarily narrow resonances, but at lower temperatures direct and broad resonance tail contributions
come to dominate. While there have been recent studies to improve the uncertainties of the contributions
of these narrow resonances, little attention has been paid to the non-resonant component of the capture
cross section. In this work, experimental measurements are reported over the energy range from 0.5
and 1.05 MeV proton beam energy. Several transitions were measured where two broad resonances were
clearly observed whose low energy tails contribute strongly to the low-energy, non-resonant, cross section.
In addition, direct capture in the23Na(p,γ)24Mg reaction was observed for the first time.
*This research utilized resources from the Notre Dame Center for Research Computing and was funded by the National Science Foundation through Grant No. PHY-2011890 (University of Notre Dame Nuclear Science Laboratory) and Grant No. PHY-1430152 (the Joint Institute for Nuclear Astrophysics - Center for the Evolution of the Elements). M.W. acknowledges support as a Wolfson Fellow of the British Royal Society at the University of Edinburgh, UK.
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Presenters
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Richard J deBoer
- University of Notre Dame