Mixed Neutron and Gamma Spectra Measurements and Calculations in Pure Iron Benchmark Assembly with Cf-252 Neutron Source

Abstract

The neutron and gamma leakage spectra measurements have been made for a benchmark spherical iron assembly with diameter of 50 cm. The Cf-252 neutron sources with different emissions were placed into the centre of the iron sphere. Independent laboratories took part in the leakage spectra measurements. The proton recoil method was used with stillbene crystals and hydrogen proportional counters for neutron spectra measurement. Spectrometers using stilbene, germanium and silicon detectors were used for gamma spectra measurement. The working range of spectrometers is for neutrons in the energy range from 0.02 to 16 MeV, and for gamma from 0.40 to 12 MeV. Some adequate calculations based on different data libraries have been done and compared with measurements. The authors propose to analyse carefully the leakage mixed neutron and gamma spectrum from an iron sphere of 50 cm diameter and than adopt that field as a standard. Analogous measurements and calculations performed on pure iron spheres of diameters 20, 30 and 100 cm are briefly discussed in the report.