Absolute frequency distributions of the effective scattering angle θ_eff for different pixels and different angular acceptances. The red and black curves correspond to the pixel of the slot position (5,5) of the central fuel assembly. The black curve represents the case where this particular slot position is empty while the red curve corresponds to the case where the slot position is filled with a fuel rod. The blue curve corresponds to a pixel between two neighbouring fuel assemblies. The top figure shows results for a fixed angular acceptance (θ_in = 0°) while the bottom figure shows results for an angular acceptance of 0° ≤ θ_in ≤ 2°. All distributions correspond to simulations with 10⁸ events.