Detection Process in Neutron Radiography

Abstract

A model of the imaging process in the direct conversion method for obtaining neutron radiographs is presented. The analysis is aimed at obtaining expressions for the attainable object resolution as a function of system and object parameters. Initially, the analysis is carried out assuming a parallel incident beam of neutrons in order to compute the best possible resolution. The results obtained are subsequently used to elucidate the effect of varying certain detection system parameters on both the resolution function and the relative exposure times for a gadolinium converter. Since the neutron beams used in radiography cannot generally be considered to be sufficiently close to parallel, the model has been extended to allow the incorporation of the effects of neutron beam divergence due to finite source size. Comparisons are presented between the results obtained from this model of the neutron radiographic process and experimental data already reported in the literature.