Measurement and Evaluation of Total Neutron Cross-Section Minima in Elemental Iron from 24 to 750 keV

Low resolution transmission experiments on 14- and 20-in.-thick samples of iron have been conducted at Rensselaer Polytechnic Institute’s linear accelerator to evaluate the adequacy of various data files in predicting total neutron cross-section minima from 24 to 750 keV. From our transmission area analysis we conclude that both the Penny-Kinney file and Version-19 file (incorporating the Columbia minima measurement) generally overestimate the total cross section in the region of minima, with the Version-19 file strongly preferred for accurate minima prediction. With the ENDF/B-III (MAT 1180) file identical to the Penny-Kinney file (except about the 24-keV minima), similar negative conclusions apply. At approximately the 24-keV minima where our resolution is sufficient to evaluate θ_t(E), we obtain excellent agreement with ENDF/B-III (MAT 1180). We quote (σt)min = 0.42 ± 0.03 b at E = 24.3 ± 0.1 keV.