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# Neutron reactions and nuclear cosmo-chronology

Abstract : The $\beta$-decay of ^{187}Re (t_{1/2}=42.3 Gyr) represents a suited cosmo-chronometer for the age of the r-process abundances, since the radiogenic part of the daughter isotope ^{187}Os is defined by the difference between the solar ^{187}Os abundance and s-process contribution to ^{187}Os. The latter component can be determined via the s-process systematics based on the stellar neutron capture cross sections of ^{186}Os and ^{187}Os. The laboratory cross section of ^{187}Os requires a significant correction for the effect of the low-lying excited state at 9.75 keV, which is strongly populated under stellar conditions. This theoretical correction can be improved by an experimental cross section for inelastic scattering to the 9.75 keV state. High resolution time-of-flight measurements of (n,\gamma) cross sections of ^{186,187,188}Os from 1 eV to 1 MeV at CERN n_TOF facility are reported. The inferred stellar cross sections differ from previously recommended values. In addition, the inelastic scattering cross section has been measured at 30 keV neutron energy via time-of-flight at the Karlsruhe 3.7 MV Van de Graaff. The implications of these results for the Re/Os clock are discussed.
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http://hal.in2p3.fr/in2p3-00151923
Contributor : Béatrice Forrler <>
Submitted on : Tuesday, June 5, 2007 - 4:21:16 PM
Last modification on : Wednesday, September 16, 2020 - 4:08:14 PM

### Citation

M. Mosconi, M. Heil, F. Käppeler, A. Mengoni, R. Plag, et al.. Neutron reactions and nuclear cosmo-chronology. International Workshop on Nuclear Physics 28th Course - Radioactive Beams, Nuclear Dynamics and Astrophysics, Sep 2006, Erice, Italy. pp.165-173, ⟨10.1016/j.ppnp.2006.12.014⟩. ⟨in2p3-00151923⟩

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