Contrast sensitivity in 14 MeV fast neutron radiography

Fast neutron radiography (FNR) is an effective non-destructive testing technique. Due to the scattering effect and low detection efficiency, the detection limit of FNR under certain conditions cannot be determined. In order to obtain the minimum detectable thickness by FNR, we studied the contrast sensitivity of FNR lead samples, both theoretically and experimentally. We then clarified the relationship between pixel value and irradiation time, and sample materials and thickness. Our experiment, using a 4-cm-thick lead sample, verified our theoretical expression of FNR contrast sensitivity.