Neutron scattering in 189Os for nucleosynthesis rates of the odd-A Os isotopes and nucleochronology

Neutron elastic and inelastic scattering cross sections have been determined for neutrons incident on 189Os at three very low energies. Cross sections for scattering to the ground state and 36.2-keV excited level have been measured for incident energies of 63.5 and 73.3 keV, and also to the 69.6-keV excited level at 97.5-keV incident energy. These measurements are combined with neutron scattering cross sections for 187Os, neutron capture cross sections, and other low-energy scattering observables to provide a basis for a single, consistent model of all data for both odd-A Os isotopes. The properly interpreted capture rates are important for the Re/Os nucleochronology and for s-process nucleosynthesis rates. The elastic and inelastic scattering cross sections provide a very-low-energy test of statistical model-flux distributions; model accuracy at very low energies is an important issue for reaction rates used in nucleosynthesis estimates