Study on scattering correction in fast neutron tomography at NECTAR facility

Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reactor. Scattered neutrons from the object become a major disturbance and bring in artifacts and deviations in reconstruction results, especially for hydrogenous material object. In this article, an iterative scattering correction method for fast neutron tomography was proposed. In each loop of iteration the scattering component of the projections will be simulated by Monte-Carlo program MCNPX based on the previous reconstruction result and then it will be subtracted from original projections. The differences between scattering components at different perspectives were quantitatively evaluated and an average scattering component image was used for all projections finally. Smooth and uniform slices with more clear edges were obtained and the new reconstructed attenuation coefficients are quite close to the real one compared to the results without scattering correction, in which case the relative error of the reconstructed attenuation coefficients is about 10%-30%.