M. Mosconi, G. Badurek, E. Jericha, H. Leeb, H. Oberhummer, -. nTOF Collaboration:
"Neutron reactions and nuclear cosmo-chronology";
Progress in Particle and Nuclear Physics, 59 (2007), S. 165 - 173.

Kurzfassung englisch:
The -decay of 187Re (t1/2 = 42.3 Gyr) represents a suited cosmo-chronometer for the age of the
r-process abundances, since the radiogenic part of the daughter isotope 187Os is defined by the difference
between the solar 187Os abundance and s-process contribution to 187Os. The latter component can be
determined via the s-process systematics based on the stellar neutron capture cross sections of 186Os and
187Os. The laboratory cross section of 187Os 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,
) cross sections of 186,187,188Os 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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