Neutron Reaction and Nuclear Cosmo-Chronology
- Forschungszentrum Karlsruhe GmbH, Institute fur Kernphysik, Germany
- ORNL
The {beta}-decay of {sup 187}Re (t=42.3Gyr) represents a suited cosmo-chronometer for the age of the r-process abundances, since the radiogenic part of the daughter isotope {sup 187}Os is defined by the difference between the solar {sup 187}Os abundance and s-process contribution to {sup 187}Os. The latter component can be determined via the s-process systematics based on the stellar neutron capture cross sections of {sup 186}Os and {sup 187}Os. The laboratory cross section of {sup 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 {sup 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.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 932033
- Journal Information:
- Progress in Particle and Nuclear Physics, Vol. 59, Issue 1; ISSN 0146-6410
- Country of Publication:
- United States
- Language:
- English
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