Displacement cross sections for iron, chromium, nickel, stainless steel, and tantalum

The effects of some recent developments on displacement cross sections published by the author for iron, chromium, nickel, 18/10 stainless steel, and tantalum are discussed. It is argued that, except for tantalum, the cross sections are essentially consistent with ENDF/B-III, and, furthermore, can be made consistent with an International Atomic Energy Agency recommended secondary displacement model by multiplying by 0.66. A re determination of the tantalum displacement cross section has been made using ENDF/B-III data and an effective displacement energy of 90 eV deduced from a recent measurement of the displacement threshold surface for tantalum. Estimates are made of the contributions to displacement cross sections of several previously ignored nonelastic processes. Finally, the usefulness of the isotropic elastic-scattering approximation at high neutron energies is discussed.