Measuring the Radiative Width of the Hoyle State in $^{12}$C

ORAL

Abstract

In stellar nucleosynthesis the conversion of helium into heavier elements begins with the triple-$\alpha$ process, in which three $\alpha$ particles combine to form $^{12}$C. The rate of this process is governed by the 0$^+$ second excited state of $^{12}$C which provides a resonance for the $\alpha$+$^{8}$Be$\rightarrow$ $^{12}$C* at an excitation energy 7.65 MeV (the Hoyle state). Overwhelmingly, the 7.65 MeV state decays by $\alpha$ particle to $^8$Be which then breaks up into two $\alpha$ particles. However, there is a small radiative decay branch (approximately 4$\times10^{-4}$) which allows the excited $^{12}$C* nucleus to decay to its ground state. A new measurement of the ratio of the radiative width to the total width has been performed by the Lawrence Livermore National Laboratory and Lawrence Berkeley National Laboratory STARS/LIBERACE collaboration. Current results and the our experimental method will be presented.

*This work was sponsored by UC-LLNL under Contract No. W-7405-Eng-48 and Grant Nos. DE-FG-05NA25929, DE-FG52-06NA26206, and DE-FG02-05ER41379.

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Authors

  • S.A. Sheets

    • Lawrence Livermore National Laboratory

  • J.T. Burke

    • Lawrence Livermore National Laboratory

  • R.D. Hoffman

    • Lawrence Livermore National Laboratory

  • E.B. Norman

    • Lawrence Livermore National Laboratory

  • L.A. Bernstein

    • Lawrence Livermore National Laboratory

  • L.W. Phair

    • Lawrence Berkeley National Laboratory

  • J. Gibelin

    • Lawrence Berkeley National Laboratory

  • M. Wiedeking

    • Lawrence Berkeley National Laboratory

  • R.M. Clark

    • Lawrence Berkeley National Laboratory

  • E. Vieitez-Rodriguez

    • Lawrence Berkeley National Laboratory

  • P. McMahan

    • Lawrence Berkeley National Laboratoryf

  • I.Y. Lee

    • Lawrence Berkeley National Laboratory

  • A.O. Macchiavelli

    • Lawrence Berkeley National Laboratory

  • C. Beausang

    • University of Richmond

  • S. Lesher

    • University of Richmond

  • B. Darakchieva

    • University of Richmond

  • M. Evtimova

    • University of Richmond

  • B. Lyles

    • University of California, Berkeley

  • M. Dolinski

    • University of California, Berkeley

  • H. Ai

    • Yale University