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Measurement of the low energy resonances in $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ reaction

ORAL

Abstract

${^{13}\rmC(a,n)^{16}\rmO}$ and $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$ are considered the two important neutron sources for the s-process, but there is still uncertainty about the total available neutron flux for the s-process. ${^{13}\rmC(a,n)^{16}\rmO}$ determines the neutron production in AGB stars while $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$, which occurs during core helium and carbon shell burning, acts as the primary neutron source in massive stars. But the $\Nean$ reaction has a negative Q-value $= -478\pm 0.05$ keV and hence operates only at high temperatures, e.g., the peak of helium burning, and during C-shell burning (if sufficient $^{22}\rm{Ne}$ is available). Moreover, the neutron-producing role of $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$ is complicated by the competing $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ reaction, which has a positive Q-value $=10614.74\pm 0.03$ keV and therefore starts operating at relatively lower temperatures, before $^{22}\rm{Ne}(\alpha,n)^{25}\rm{Mg}$ can kick in. Hence it is important to investigate the reaction rate of $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ in order to put quantitative constraints on the neutron production for the weak s-process. It was experimentally observed by the direct measurements that the reaction rate for $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ is strongly impacted by the low energy resonance at $\rmE_{\alpha}$(lab) = 828 keV, but the recent indirect measurements show that the resonance at $\rmE_{\alpha}$(lab) = 653 keV can appreciably impact the $^{22}\rm{Ne}(\alpha,\gamma)^{26}\rm{Mg}$ reaction rate. The measurement of both these resonances was performed at Sanford Underground Research facility (SURF), CASPAR. Preliminary analysis of the resonance strengths for these two resonances will be presented.

Presenters

  • Shahina Shahina

    University of Notre Dame

Authors

  • Shahina Shahina

    University of Notre Dame

  • Michael C F Wiescher

    University of Notre Dame, The Joint Institute for Nuclear Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA

  • Daniel Robertson

    University of Notre Dame

  • Joachim Goerres

    University of Notre Dame, The Joint Institute for Nuclear Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA

  • Anna Simon

    University of Notre Dame

  • Edward J Stech

    University of Notre Dame

  • Manoel Couder

    University of Notre Dame

  • Frank Strieder

    South Dakota School of Mines & Technology, South Dakota Sch Mines & Tech

  • Phillip Scholz

    University of Notre Dame, The Joint Institute for Nuclear Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA

  • Orlando J Gomez

    University of Notre Dame

  • Rebeka Kelmar

    University of Notre Dame

  • Alexander C Dombos

    University of Notre Dame, FRIB

  • August Gula

    University of Notre Dame

  • Thomas Kadlecek

    South Dakota School of Mines & Technology, South Dakota School of Mines & Technolog

  • Mark Hanhardt

    South Dakota Science & Technology Authority (SDSTA)