Spectrum of leakage neutrons from an iron sphere with a californium neutron source

A series of macroscopic investigations of the passage of neutrons through different media revealed a significant discrepancy between the experimental and computed spectra of leakage neutrons when the experimental spheres had a large thickness. For iron, one of the most common structural materials used in nuclear and thermonuclear reactors and their shielding, the maximum discrepancy is 50% in the neutron energy range 0.01-14 MeV. To check this discrepancy we performed new measurements and calculations using the latest versions of libraries of neutron data on the spectra of leakage neutrons from an 18 cm thick iron sphere with a californium neutron source at the center.