Performance and calibration of a neutron image intensifier tube based real-time radiography system

Image calibration is central to extending the capabilities of neutron radiography beyond mere visualization. However, the effects of scattered neutrons and variations in background image intensity adversely affect quantitative radiography. We describe the calibration of a real-time neutron radiography system that limits these effects and which is applicable to systems with variable digitizer gain and offset. A neutron image intensifier tube coupled to a vidicon camera with a capture rate of 30 frames/s was used. The system could account for 10 ml of water entering the field of view to within 2% and could measure the variation in thickness of a graphite wedge to within 2.3%. The spatial resolution was 450 μm for a field of view of 410 cm². The image persistence half life was ∼0.3 s and the system was functional for quantitative radiography with neutron fluxes above ∼5*10⁵n/cm²/s.