Neutron transmission imaging with a portable D-T neutron generator

Purpose A portable fast-neutron imaging system is being developed to provide complementary information to field X-ray imaging.Applications include inspection of vehicles and infrastructure for corrosion,measurement of material levels in containers,and inspection of munitions and suspicious packages.While fast-neuron imaging generally provides lower imaging resolution compared to X-rays,fast-neutron interaction cross-sections have a weak dependence on material Z.This enables imaging of low-Z materials inside high-Z materials.Here,we discuss the limitations and current improvements in fast-neuron imaging.Methods Limitations in portable fast-neutron imaging systems include low D-T neutron generator output,low light pro-duction in ZnS(Cu)imaging scintillators,low resolution due to scintillator thickness and D-T spot size,and digital-panel darknoise that varies in time and position and that can be 100×larger than the neutron signal.We have made improvements in these areas through development of a segmented high light yield scintillator,panel noise mitigation techniques,and testing of new high-output,small spot size D-T neutron generators.Results The segmented high light yield fast-neutron scintillator demonstrated 5×increase in light compared to ZnS(Cu).An additional 2×improvement in signal-to-noise was demonstrated with panel-noise mitigation techniques.Our MCNP calculations also show good agreement with neutron imaging results Conclusions We have demonstrated improvements in fast-neutron imaging through development of a segmented high light yield neutron scintillator,mitigation of digital panel noise,and preliminary testing with new high-output,small spot size D-T neutron generators.We have also demonstrated good results modeling fast-neutron images and scatter effects using MCNP.