O-17(N,ALPHA)C-14 CROSS-SECTION FROM 25 MEV TO APPROXIMATELY 1 MEV

We have measured the O-17(n,alpha)C-14 cross section from thermal energy to approximately 1 MeV. A bump in the data near 3 keV could be fitted by a state whose properties are consistent with a known subthreshold J-pi = 1- level at E(x) = 8.039 MeV. The cause of the 1/upsilon cross section near thermal energy could not be determined although the known 2+ state at 8.213 MeV was found to be too narrow to contribute much to the thermal cross section. Our data are compared to measurements made via the inverse reaction. There are many differences between the two sets of data. The astrophysical reaction rate was calculated from the measured cross section. This reaction plays a role in the nucleosynthesis of heavy elements in nonstandard big-bang models. At big-bang temperatures, the experimental rate was found to be in fair agreement with the rate estimated from the previously known properties of states of O-18 in this region. Furthermore, using the available information from experiments, it was estimated that the O-17(n,alpha)C-14 rate is approximately a factor of 10(3)-10(4) times larger than the O-17(n,gamma)O-18 rate at big-bang temperatures. As a result, there may be significant cycling between C-14 and O-17 resulting in a reduction of heavy-element nucleosynthesis.