The Development of a Parameterized Scatter Removal Algorithm for NMIS Imaging

Neutron radiography is a powerful investigative technique for analyzing the interior structure of an object. If the true attenuation of neutrons at each position in the object can be measured, the attenuation coefficients can be computed and used to identify the materials inside the object. However, scattered neutrons will contribute to the measured neutron flux and reduce the measured attenuation. The Nuclear Materials Identification System (NMIS) uses a time-tagged and electronically collimated D-T neutron source to reduce this effect; however, some of the scattering component remains. This work used Monte Carlo simulations to calculate the scattering component for a variety of scenarios. The scattering for each scenario was fit using a Gaussian distribution to derive a point scatter function. These point scatter functions were used to develop a parameterized scatter removal algorithm that can calculate and remove the scattering component for a wide range of scenarios based on operator inputs. The process used to calculate the scatter functions and develop the scatter removal algorithm is discussed in detail. Examples of simulated and experimental measurements are used to test and validate the algorithm.