Experimental Investigation of the Ne19(p,γ)20Na Reaction Rate and Implications for Breakout from the Hot CNO Cycle

J. Belarge, S. A. Kuvin, L. T. Baby, J. Baker, I. Wiedenhöver, P. Höflich, A. Volya, J. C. Blackmon, C. M. Deibel, H. E. Gardiner, J. Lai, L. E. Linhardt, K. T. Macon, E. Need, B. C. Rasco, N. Quails, K. Colbert, D. L. Gay, and N. Keeley
Phys. Rev. Lett. 117, 182701 – Published 27 October 2016

Abstract

The Ne19(p,γ)Na20 reaction is the second step of a reaction chain which breaks out from the hot CNO cycle, following the O15(α,γ)Ne19 reaction at the onset of x-ray burst events. We investigate the spectrum of the lowest proton-unbound states in Na20 in an effort to resolve contradictions in spin-parity assignments and extract reliable information about the thermal reaction rate. The proton-transfer reaction Ne19(d,n)Na20 is measured with a beam of the radioactive isotope Ne19 at an energy around the Coulomb barrier and in inverse kinematics. We observe three proton resonances with the Ne19 ground state, at 0.44, 0.66, and 0.82 MeV c.m. energies, which are assigned 3+, 1+, and (0+), respectively. In addition, we identify two resonances with the first excited state in Ne19, one at 0.20 MeV and one, tentatively, at 0.54 MeV. These observations allow us for the first time to experimentally quantify the astrophysical reaction rate on an excited nuclear state. Our experiment shows an efficient path for thermal proton capture in Ne19(p,γ)Na20, which proceeds through ground state and excited-state capture in almost equal parts and eliminates the possibility for this reaction to create a bottleneck in the breakout from the hot CNO cycle.

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  • Received 16 October 2015

DOI:https://doi.org/10.1103/PhysRevLett.117.182701

© 2016 American Physical Society

Physics Subject Headings (PhySH)

Nuclear PhysicsGravitation, Cosmology & Astrophysics

Authors & Affiliations

J. Belarge1, S. A. Kuvin1, L. T. Baby1, J. Baker1, I. Wiedenhöver1, P. Höflich1, A. Volya1, J. C. Blackmon2, C. M. Deibel2, H. E. Gardiner2, J. Lai2, L. E. Linhardt2, K. T. Macon2, E. Need2, B. C. Rasco2, N. Quails3, K. Colbert3, D. L. Gay3, and N. Keeley4

  • 1Physics Department, Florida State University, Tallahassee, Florida 32306, USA
  • 2Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Lousiana 70803, USA
  • 3Department of Physics, University of North Florida, Jacksonville, Florida 32224, USA
  • 4National Centre for Nuclear Research, ul. Andrezja Sołtana 7, 05-400 Otwock, Poland

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Issue

Vol. 117, Iss. 18 — 28 October 2016

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