The <sup>13</sup>C(α, n)<sup>16</sup>O differential cross section

ORAL

Abstract

Neutron production for the slow neutron capture process (s-process) is dominated by (α,n) reactions on light nuclei during stellar helium burning. Chief among these is the 13C(α,n)16O reaction, whose low energy cross section is enhanced by the presence of broad resonances and subthreshold states. Experimental measurements have been reported recently at both the LUNA and JUNA underground facilities, reaching to unprecedentedly low energies. These measurements have verified R-matrix extrapolations, constrained by transfer reaction determinations of the dominant subthreshold resonance strength, that the cross section is lower than previous above ground measurements indicated. To further reduce the uncertainty, we report measurements of the differential cross section of the 13C(α,n)16O reaction, which extend from laboratory α-particle energies of 0.8 to 6.5 MeV in approximately 10 keV energy steps at 18 angles between 0 and 160◦, resulting in over 700 distinct angular distributions. These measurements are the first accurate differential cross section measurements of this reaction below 1 MeV. We use these differential data to augment the previous state-of-the-art R-matrix fit of the low energy 13C(α,n)16O reaction and use Bayesian uncertainty estimation to demonstrate that the differential data decreases the uncertainty by a factor of two, from ≈10% to ≈5% over the energy region of astrophysical interest.

*This research was funded by the National Science Foundation through Grant No. PHY-2011890, PHY-1430152 and OISE-1927130 (IReNA). This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award Number DE-AC05-00OR22725. LANL researchers are supported by the U.S. Department of Energy, through the Los Alamos National Laboratory, operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract No. 89233218CNA000001) and by the Office of Science, Office of Nuclear Physics, under the Nuclear Data InterAgency Working Group Research Program.

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Presenters

  • Richard J deBoer

    • University of Notre Dame

Authors

  • Richard J deBoer

    • University of Notre Dame

  • Michael T Febbraro

    • Air Force Institute of Technology

  • Dan W Bardayan

    • University of Notre Dame

  • Chevelle Boomershine

    • University of Notre Dame

  • Kristyn H Brandenburg

    • Ohio University

  • Carl R Brune

    • Ohio University

  • Sydney D Coil

    • University of Notre Dame

  • Manoel Couder

    • University of Notre Dame

  • Joseph A Derkin

    • Ohio University

  • Stefania Dede

    • Texas A&M University, University of Notre Dame

  • Ruoyu Fang

    • University of Notre Dame

  • Adam L Fritsch

    • Gonzaga University

  • August Gula

    • Los Alamos National Laboratory

  • Gy. Gyurky

    • ATOMKI

  • Brennan T Hackett

    • Max Planck Institute for Physics

  • Gulakhshan M Hamad

    • Ohio University

  • Yenuel Jones-Alberty

    • Ohio University

  • Rebeka Kelmar

    • University of Notre Dame

  • Khachatur Manukyan

    • University of Notre Dame

  • Miriam Matney

    • University of Notre Dame

  • John P McDonaugh

    • University of Notre Dame

  • Zachary P Meisel

    • Ohio University

  • Shane Moylan

    • University of Notre Dame

  • Jason Nattress

    • Oak Ridge National Laboratory

  • Daniel M Odell

    • Ohio University

  • Patrick O'Malley

    • University of Notre Dame

  • Mark W Paris

    • Los Alamos Natl Lab

  • Daniel Robertson

    • University of Notre Dame

  • Shahina Shahina

    • University of Notre Dame

  • N. Singh

    • Ohio University

  • Karl Smith

    • Los Alamos National Laboratory

  • Michael S Smith

    • Oak Ridge National Laboratory

  • Edward Stech

    • University of Notre Dame

  • Wanpeng Tan

    • University of Notre Dame

  • Michael C F Wiescher

    • University of Notre Dame