<p>This thesis contains two parts; Both of which are parts of the requirements for the Degree of Master of Engineering </p> </p> <p> Part A: Industrial Project</p> </p> <p> Part B: McMaster (On-Campus) Project </p> / <p> This document reports the results of a study of several parameters of a neutron radiographic system of the direct conversion type, and of their effects on certain image characteristics. These parameters are: thickness of the converter, backing material of the very thin converter layers, level of water in the beam tube, exposure time, and film type. The image characteristics are relative optical density, specific contrast, and unsharpness, the latter interpreted quantitatively through the edge-spread function. Theoretical treatments and empirical data are presented and compared. Emphasis is put on investigations of the perfonnance of thin (~2000 A) layers of gadolinium converter, and on the experimental analysis of the edge-spread function. </p> / Thesis / Master of Engineering (ME)

<p> In analyzing the processes involved in neutron radiography, there is a need for a well-defined mathematical structure which can simultaneously be used in practical situations without great difficulty. In this report, the edge-spread function method of analysis is considered in some detail. The basic theory is developed, and both the general and the specific viewpoint are considered, in terms of the mathematical functions used. The usefulness of ESF theory in predicting optical density patterns is illustrated. Specific applications of the theory are developed; in particular, studies of image resolution and unsharpness are undertaken. </p> <p> To determine whether or not ESF methods are a good representation of the physical situation, some alternate methods which consider radiography from a more basic viewpoint are developed. The first of these is a strictly numerical approach, where experimental data is examined without specifying a model for the image formation process; a matrix formulation suitable for characterizing an image is developed. </p> <p> The second alternate method involves the use of Monte Carlo methods; this allows the incorporation of more realistic parameters into the analysis. For example, screen-film separation and object scattering of neutrons, and their effects on the image, are evaluated. Finally, a two-dimensional analysis of a simple problem is considered, with the end result being a confirmation of the usefulness of ESF theory. </p> / Thesis / Master of Engineering (MEngr)

<p> Some experiments designed to test the validity of the edge-spread function (ESF) model for neutron radiographic image formation are described; in addition the experiments are meant to illustrate the application of ESF methods to two areas of practical concern. First, the prediction of optical density curves for specified material and geometric configurations is considered; then, the use of ESF methods in dimensioning irradiated reactor fuel elements is examined. Overall, the results indicate that within the framework of assumptions which ESF theory is based upon, the correlation between theory and experiment is excellent. The results also suggest that in situations which deviate from the theoretical ideal, the ESF method may serve as a good first approximation to more complex models. </p> / Thesis / Master of Engineering (ME)