Measurements of the differential cross sections for elastic and inelastic scattering of 14-MeV neutrons in natural chromium, iron, nickel, and niobium

The time-of-light technique was used with the "ring" scattering geometry in a laboratory with low neutron-scattering background to measure the angular distributions of the cross sections for elastic and inelastic scattering o f 14-MeV neutrons in natural chromium, iron, nickel and niobium. Specifical ly for inelastic scattering, the measurements included the 1.43- and 4.56-M eV levels of Cr-52 the 0.85-, (2.94 to 3.12)-, and (4.46 to 4.51)-MeV level groups of Fe-56; the 1.33-MeV level of Ni-60 combined with the 1.45-MeV le vel of Ni-58; and the 4.48-MeV level of Ni-58. Pulses of neutrons with time width of 0.9 to I. I ns were produced via the D-T reaction in a 150-keV li near accelerator with average intensities of 9 x 10(8) n/s. The scattering angles ranged from similar to 16 to similar to 160 deg, with a typical step of similar to 10 deg. The overall uncertainty for the elastic scattering c ross section was in the range of 7 to 10% for all materials, except around the minima of the angular distribution for niobium. The uncertainties far t he inelastic scattering cross sections were estimated to be between 8 and 2 4%. The measured angular distributions were compared with the evaluations i n the ENDF/B-VI, JENDL-3, CENDL-2, BROND-2, and JEF-2 nuclear data librarie s. For elastic scattering, there are no significant discrepancies in genera l neither among the evaluations nor between the present data and the evalua tions. For the inelastic scattering there are substantial discrepancies bot h in shape and magnitude among the evaluations (when available) as well as between the present data and the evaluations.