We have made improved measurements of the neutron capture and total cross sections for {sup 137}Ba over a sufficiently wide range of energies so that the reaction rate at s-process temperatures (kT=6{endash}23 keV) can be determined solely from the data. These rates are crucial for the interpretation of recently discovered anomalies of Ba isotopes in silicon carbide grains from the Murchison meteorite. Recent stellar models of the s process are in agreement with the meteoric anomaly data for Ba only if the {sup 137}Ba(n,{gamma}) reaction rate is 20{percent} larger than the previously accepted rate. Our reaction rates at s-process temperatures are in agreement with the extrapolated reaction rate from the most recent previous measurement. Hence, our results uphold, and place on much firmer footing, the discrepancy between recent stellar models of the s-process and the meteoric anomaly data. {copyright} {ital 1998} {ital The American Physical Society}

The Li-7(n,gamma)Li-8 cross section is important,in inhomogeneous big bang models, and as a constraint on model parameters used to determine the solar Be-7(p,gamma)B-8 reaction rate. Values of the Li-7(n,gamma(0))Li-8 reaction cross section were measured for neutron energies between 1.5 and 1340 eV at the Oak Ridge Electron Linear Accelerator. The normalization of the cross section was determined by measuring the gamma-ray yield from the Li-7(n,gamma(0))Li-8 reaction relative to that from the B-10(n,alpha gamma)Li-7 reaction. The cross section was found to have the inverse neutron-velocity relationship (1/v) indicative of s-wave capture. These results help resolve ambiguities in previous measurements.