Optimisation of Instrumental Neutron Activation Analysis.

The objective of this thesis is to establish techniques and procedures of instrumental Neutron Activation Analysis (INAA), that either produce a better signal-to-noise ratio or reduce the errors involved. Cyclic neutron activation analysis is described, and methods for its optimisation and simulation are implemented and compared with conventional activation analysis. The simulation has included theoretical calculation of Bremsstrahlung, and consideration of single and double escape peaks. Another method investigated for enhancing the signal-to-noise ratio of short lived activity utilised Compton suppression. Massfractionation has been investigated as a new approach to analysis of hot samples as well as a means for ensuring that a representative mass of a given element in a sample is used. This also allowed the development of a novel technique for the determination of the sampling factor for elements of interest. Determination of short-lived fission products half lives gamma-ray energies and yields has made possible the characterisation of the short-lived fission product spectrum. This has allowed us to both study the variation of the signal-to-noise ratio of the most intense gamma rays and test their possible use for uranium determination. The determination of 26 elements including uranium and thorium in a Syrian geological survey was conducted and the usefulness of cluster analysis in detecting systematic and random errors was demonstrated. The utilisation of microcomputer for data acquisition and the development of data processing of such data on a mainframe computer were integrated in order to achieve maximum flexibility