High-resolution fast-neutron gamma-ray production cross sections for iron up to 2100 keV

High-resolution gamma-ray production cross sections for the 846-keV gamma ray of iron have been measured up to an incident neutron energy of 2100 keV. The measurements were performed using the Oak Ridge Electron Linear Accelerator as the neutron source, and they were obtained by a ratio measurement to the 7Li 477-keV gamma-ray cross sections. Three NE-213 detectors were used at 30, 90, and 125 deg to derive the total inelastic cross sections and the angular distributions. The 1250 angular distributions measured with approximately 0.1 ns/m resolution show considerable fluctuations as a function of energy over the resonances seen in the inelastic cross sections. The results are compared to the ENDF/B-IV evaluation, high-resolution data at 125 deg and, after suitable averaging, with recent monoenergetic neutron source data that average over the structure experimentally. The general consistency of the data with recent measurements, using different techniques and normalization procedures, indicates that our knowledge of this important cross section for fission reactor applications may now be known to an accuracy better than 10 percent. This is a significant achievement in view of the wide scatter of earlier data on such a fluctuating cross section