Disentangling the 16O cross section using light water and heavy water benchmark assemblies

Highlights: • Measurement of fast neutron flux penetrating through heavy and light water spheres. • Effect of different data libraries on calculations. • Sensitivity analysis of ¹⁶O elastic, inelastic and (n, alpha) cross sections. - Abstract: Fast neutron leakage spectra from the light and heavy water sphere of 30 cm in diameter with neutron source in its centre were measured by a stilbene scintillation detector in the region of 1–10 MeV in the distance of 85 cm from the spheres surface. We use the light and heavy water to eliminate the effect of hydrogen. ²⁵²Cf with the approximate emission rate of 5.5E8 n/s was used as a neutron source for all measurements involved and was placed in the centres of the spheres. The measured neutron spectra are compared with MCNP transport code calculations in ENDF/B-VII.0, ENDF/B-VIII.b4 and JENDL-4 nuclear data libraries. Experimental results for both cases follows similar trend. The best agreement is achieved with ENDF/B-VIII.b4 library in both cases. All libraries underestimate experimental measurement in the region of 3–4 MeV. Furthermore, JENDL-4 library overestimates experiment in the region of 4–6.5 MeV. In addition, we performed cross section sensitivity analysis for elastic, inelastic and (n,α) reaction in JENDL-4 and ENDF/B-VIII.b4 libraries since they have almost independent evaluations of ¹⁶O.