Abstract
The application of instrumental neutron activation analysis, principally employing short-lived isotopes, to archaeological and environmental studies is described. Techniques for the production and measurement of short-lived isotopes using a reactor facility are discussed and evaluated for a variety of sample matrices by the estimation of elemental detection limits. Cyclic activation analysis, ideally suited for the measurement of isotopes with tau½ < 60s, is considered and optimised with respect to the 'signal-to-noise' ratio of a radionuclide of interest. The potential of the technique, in the low energy photon region (< 250 keV), is demonstrated by determination of elemental sensitivities in a variety of biological materials. In an environmental study of Oxford City-Centre, the analysis of air particulates provides results for 8 time-varying elemental concentrations. Correlations are drawn between these elements, traffic flow, filter obscuration and meteorological data, also the concentrations of 5 hydrocarbons measured by gas chromatography. The suitability of thermal, epithermal and reactor neutrons is investigated for the measurement of bulk, minor and trace elements in soils. The most appropriate method is then applied to the study of variations in elemental concentration with soil depth, for the purpose of locating buried soils of archaeological significance. These results are compared with additional physical measurements performed on the soils, such as loss on ignition and particle size determination. The technique of cluster analysis is described and employed to aid interpretation of the multi-elemental results obtained. A method is devised, employing cyclic activation, for the estimation of fluorine, through the 20F isotope (tau½ ~ 11s), in a bone matrix. Corrections are applied to eliminate the interference from a fast neutron reaction of sodium. The technique is proven to be multi-elemental, more than 10 elements per biological matrix being detected. Finally, the method is discussed in relation to its potential application for the dating of ancient bone, where the multi-elemental capability is an advantage.