Neutron-Induced Gamma-Ray Production in ⁵⁷Fe for Incident Neutron Energies Between 0.16 and 21 MeV

Interactions of neutrons with the iron isotope ⁵⁷Fe have been studied by measuring gamma-ray production cross sections for incident neutron energies between 0.16 and 21 MeV. Neutrons produced by the Oak Ridge Electron Linear Accelerator impinged on a metallic iron sample enriched to 93% in the isotope ⁵⁷Fe. The resulting gamma radiation was detected using a 100-cm³ Ge(Li) detector placed at 125 deg with respect to the neutron beam line. A complete description of the experiment is given. Absolute gamma-ray production cross sections were measured for gamma rays corresponding to the ⁵⁷Fe(n,n′ γ)⁵⁷Fe, ⁵⁷Fe(n,γ)⁵⁸Fe, ⁵⁷Fe(n,α)⁵⁴Cr, ⁵⁷Fe(n,2n)⁵⁶Fe, and ⁵⁷Fe(n,p)⁵⁷Mn reactions. The cross section for the ⁵⁷Fe(n,2n)⁵⁶Fe reaction exceeds 1 b for E_n ∼ 15 MeV, and the cross section for the ⁵⁷Fe(n,p)⁵⁷Mn reaction exceeds 0.2 b for E_n ∼ 9 MeV. A new excited state is postulated for ⁵⁷Mn to account for observed data. Several new transitions are reported for decay of levels in ⁵⁷Fe. Measured cross sections are compared with data obtained from the current ENDF/B evaluation.