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Integral benchmark experiments on a large copper block using the GELINA accelerator to validate natCu neutron cross sections from different neutron cross-sectional databases

Abstract: 

A neutronics integral benchmark experiment on a pure copper block, aimed at testing and validating recent copper nuclear data libraries, has been performed at Geel Electron LINear Accelerator Facility (GELINA). GELINA is a powerful photoneutron source using a 75- μA , 110-MeV electron beam impinging on a depleted U rotating target, producing a white neutron spectrum ranging from the epithermal region up to about 20 MeV with a mean energy of about 1.4 MeV and intensity up to 3.2×1013 n/s. A large nat Cu block (dimensions 60×60×60 cm 3 ) has been positioned at 100 cm from the target. Thin activation foils were used as neutron flux probes and located inside the block in six positions at different depths with respect to the main neutron propagation direction. Materials whose activation cross section are sensitive to different neutron energy ranges were used, and the measured fluxes were compared with calculations performed using the MCNP6 neutron transport code coupled to different neutron cross-sectional databases (FENDL3.1, JEFF33_T2, and ENDF 7.1). The MCNP6 calculation also used the neutron spectrum produced by the GELINA accelerator. This is the first time that a neutronics integral experiment on copper is performed using such a white neutron spectrum and the results of our comparison could be used to validate the neutron copper cross sections in the neutron energy range covered by GELINA. The C/E results, taking into account the sources of uncertainties, are satisfactory: no large differences are observed among the result obtained using the three cross-sectional databases; however, the JEFF-3.3 seems, slightly, better predict the results.