KFK γ-ray leakage Iron sphere benchmark with Cf source: entry for SINBAD and analysis

An information necessary for the new entry in the SINBAD database was collected and thoroughly analyzed. It covers the measurement of the γ-ray leakage spectra from three iron spheres of diameter 20, 25 and 35 cm with a Cf source in the center. The experiment was performed at Kernforschungszentrum Karlsruhe (KFK) around 1977 and was an extension of measurements of the neutron leakage spectra, the latter were already compiled in SINBAD. This report includes the detailed description of the KFK experiment, the numerical γ-ray leakage spectra and other information necessary for the nuclear data validation. The MCNP input deck was assembled and used for the sample calculations of the radiation transport and sensitivities with the ENDF/B-VIII.0 neutron reaction cross section data. The spontaneous fission of ${}^{252}$Cf was modelled as a source of neutrons and gammas, both prompt and delayed. If the neutron emission data are rather well established, the knowledge of the γ-ray data is much poorer. In the present work the prompt γ-ray spectrum and multiplicities were combined from known measurements and theoretical calculations. The knowledge of the delayed gamma-ray multiplicities and spectra from ${}^{252}$Cf(s.f.) are still relying on the old and scarce measurements or compilations. ... mehrThe KFK experiment was compared with similar measurements performed at IPPE a few years later. Agreement between them, confirmed by direct comparison and similar conclusions derived from Monte-Carlo analysis, proves the reliability of both experiments.