New neutron capture and transmission measurements for 134,136Ba at ORELA and their impact on s-process nucleosynthesis calculations

We have made high-resolution neutron capture and transmission measurements on isotopically enriched samples of 134Ba and 136Ba at the Oak Ridge Electron Linear Accelerator (ORELA) in the energy range from 20 eV to 500 keV. Previous measurements had a lower energy limit of 3 - 5 keV, which is too high to determine accurately the Maxwellian-averaged capture cross section at the low temperatures (kT ∼ 6 - 12 keV) favored by the most recent stellar models of the s-process. Our results for the astrophysical reaction rates are in good agreement with the most recent previous measurement at the classical s-process temperature, kT = 30 keV, but show significant differences at lower 40 temperatures. We discuss the astrophysical implications of these differences