Measurement of the Cascade Transition via the First Excited State of O16 in the C12(α,γ)O16 Reaction, and Its S Factor in Stellar Helium Burning

C. Matei, L. Buchmann, W. R. Hannes, D. A. Hutcheon, C. Ruiz, C. R. Brune, J. Caggiano, A. A. Chen, J. D’Auria, A. Laird, M. Lamey, ZH. Li, WP. Liu, A. Olin, D. Ottewell, J. Pearson, G. Ruprecht, M. Trinczek, C. Vockenhuber, and C. Wrede
Phys. Rev. Lett. 97, 242503 – Published 15 December 2006

Abstract

Radiative α-particle capture into the first excited, Jπ=0+ state of O16 at 6.049 MeV excitation energy has rarely been discussed as contributing to the C12(α,γ)O16 reaction cross section due to experimental difficulties in observing this transition. We report here measurements of this radiative capture in C12(α,γ)O16 for center-of-mass energies of E=2.22MeV to 5.42 MeV at the DRAGON recoil separator. To determine cross sections, the acceptance of the recoil separator has been simulated in GEANT as well as measured directly. The transition strength between resonances has been identified in R-matrix fits as resulting both from E2 contributions as well as E1 radiative capture. Details of the extrapolation of the total cross section to low energies are then discussed [S6.0(300)=2515+16keVb] showing that this transition is likely the most important cascade contribution for C12(α,γ)O16.

  • Figure
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  • Received 19 June 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.242503

©2006 American Physical Society

Authors & Affiliations

C. Matei1, L. Buchmann2,*, W. R. Hannes3, D. A. Hutcheon2, C. Ruiz4, C. R. Brune1, J. Caggiano2, A. A. Chen5, J. D’Auria4, A. Laird2,†, M. Lamey4,‡, ZH. Li2,§, WP. Liu6, A. Olin2, D. Ottewell2, J. Pearson5, G. Ruprecht2, M. Trinczek2, C. Vockenhuber4, and C. Wrede4,∥

  • 1Ohio University, Athens, Ohio, USA
  • 2TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada, V6T 2A3
  • 3University of Konstanz, Department of Physics, Germany
  • 4Simon Fraser University, Burnaby, British Columbia, Canada
  • 5McMaster University, Hamilton, Ontario, Canada
  • 6China Institute of Atomic Energy, Beijing, People’s Republic of China

  • *Electronic address: lothar@triumf.ca
  • Present address: Department of Physics, University of York, York, U.K.
  • Present address: Department of Physics, University of Alberta, Edmonton, Canada.
  • §Present address: China Institute of Atomic Energy, Beijing, People’s Republic of China.
  • Present address: Yale University, New Haven, CT, USA.

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Vol. 97, Iss. 24 — 15 December 2006

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