Factors affecting image formation in accelerator-based fast neutron radiography

Fast neutrons can be generated with accelerators via various reactions. The reactions 7Li(p, n)7Be and D(d, n)3He were employed for this study to generate neutrons at various energies. Radiographs of different materials have been produced and analysed in terms of contrast and resolution. Monte Carlo methods have been used to evaluate the physical factors determining the image quality in these practical situations. In each case the theoretical and experimental values were compared. A series of gamma-ray radiographs generated using a Co-60 source provided an experimental benchmark for comparison with fast neutron radiographs. The neutron radiographs were generated as a function of fast neutron producing reaction (neutron energy spectrum), scintillator type and thickness, charged particle energy, imaging geometry and sample material. Both a CCD camera operating at room temperature and cooled CCD were used in the imaging process. (orig.)