| M. Mosconi et al. (G. Aerts, S. Andriamonje, E. Berthoumieux, C. Carrapico, W. Dridi, F. Gunsing, C. Lampoudis, J. Pancin, L. Perrot, A. Plukis) |
The beta-decay of Re (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 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 187Os. 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, γ ) 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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