Sm-147(n,alpha) cross section measurements from 3 eV to 500 keV: Implications for explosive nucleosynthesis reaction rates

We have measured the Sm-147(n, alpha) cross section from 3 eV to 500 keV. These data were used to test nuclear statistical models which must be relied on to calculate the rates for as yet unmeasurable reactions occurring in explosive nucleosynthesis scenarios. It was found that our data are in reasonably good agreement with the reaction rate predicted by an older model but that the sates predicted by two very recent models are roughly a factor of 3 different from the data (in opposite directions). A detailed analysis indicates the strong dependence on the employed optical alpha potentials. These results, together with counting rate estimates for future experiments indicate that (n, alpha) measurements will be useful for improving reaction rate predictions across the global range of masses needed for explosive nucleosynthesis calculations.