Gamma-Ray Spectra Arising from Fast-Neutron Interactions in Elements Found in Soils, Concretes, and Structural Materials

Measurements have been made at the Tower Shielding Facility of the spectra of secondary gamma rays arising from fast-neutron interactions in samples of natural iron, aluminum, copper, zinc, titanium, potassium, calcium, sodium, silicon, nickel, barium, sulfur, and a type-321 stainless steel. The absolute spectra are expressed as values of (Δ E_γ) = 4π d/dΩ (ΔE_γ, 90 deg), where (ΔE_γ) is the production cross section in millibarns averaged over an incident neutron spectrum from 1 to 14 MeV for 0.5-MeV wide gamma-ray intervals lying between approximately 1 and 6.5 MeV in gamma-ray energy. These data are intended primarily as integral checks on existing and future production cross-section sets which are differential in both the gamma-ray and neutron energy. Agreement with existing sets of data is adequate for iron, nickel, chromium, calcium, and aluminum. The agreement is fair to poor for the remaining elements where comparisons could be made.