The Astrophysical $^{187}$Re$^{187}$Os Ratio: Measurement of the $^{187}$Re(n, 2n $\gamma$)$^{186m}$Re Destruction Cross Section

ORAL

Abstract

We have initiated a program to measure neutron-induced cross sections on $^{187}$Re using monoenergetic neutron beams and an array of HPGe $\gamma$-ray detectors at TUNL. Our emphasis is on measuring transitions in the $^{187}$Re(n, 2n ) reaction that populate the long-lived isomeric state, $^ {186m}$Re. These data are needed to decrease uncertainties in the $^{187} $Re/$^{187}$Os cosmochronometer, which dates the $r$-process nucleosynthesis. Results from a first run using a pulsed 12 MeV neutron beam will be presented, and an overview of planned measurements that will measure the excitation function making use of both prompt $\gamma$-ray detection and activation techniques will be given.

*Partly supported by the U.S. Dept. of Energy DE-FG02-97ER41033, DE-FG02-97ER41042, DE-FG02-97ER41041, DE-AC02-06CH11357 and NSF-05-52723

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Authors

  • J.H. Kelley

    • NC State U and Triangle Universities Nuclear Laboratory

  • D.B. Masters

    • Samford U

  • S. Hammond

    • UNC-Chapel Hill and TUNL

  • H.J. Karwowski

    • UNC-Chapel Hill and TUNL

  • E. Kwan

    • Duke U and TUNL

  • A. Hutcheson

    • Duke U and TUNL

  • A.P. Tonchev

    • Duke U and TUNL

  • Werner Tornow

    • Duke University and TUNL
    • Duke U and TUNL
    • Duke University \& TUNL

  • F.G. Kondev

    • Argonne National Laboratory

  • S. Zhu

    • Argonne National Laboratory