FACTORS AFFECTING IMAGE-FORMATION IN ACCELERATOR-BASED FAST-NEUTRON RADIOGRAPHY

Fast neutrons can be generated with accelerators via various reactions . The reactions Li-7(p,n)Be-7 and D(d,n)He-3 were employed for this st udy to generate neutrons at various energies. Radiographs of different materials have been produced and analysed in terms of contrast and re solution. Monte Carlo methods have been used to evaluate the physical factors determining the image quality in these practical situations. I n each case the theoretical and experimental values were compared. A s eries of gamma-ray radiographs generated using a Co-60 source provided an experimental benchmark for comparison with fast neutron radiograph s. The neutron radiographs were generated as a function of fast neutro n producing reaction (neutron energy spectrum), scintillator type and thickness, charged particle energy, imaging geometry and sample materi al. Both a CCD camera operating at room temperature and cooled CCD wer e used in the imaging process. (C) 1998 Elsevier Science B.V.