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  • Author or Editor: W. Lyon x
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Abstract  

The growth of prompt nuclear analysis including Rutherford backscattering is analysed by using scientometric methods. Publication productivity, the number and kinds of nuclear reactions used, elements analyzed, manpower demography and migration and the diffu of prompt methods are discussed.

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Abstract  

In using positrons as analytical tools the experimenter has two quite different options. The first and more obvious is to duplicate electron methods with positrons and see what differences (if any) result. The second is to exploit a unique characteristic of positrons, such as the formation and decay of the positronium atom, to study chemical composition and surface characteristics. Because positrons do not exist freely in our world, they must be obtained from radioactive sources or nuclear interactions. Source intensity has consequently been a limiting factor in experiments that attempt to duplicate electron applications. Some methods of producing and moderating positrons that have been developed here (and elsewhere) are described as well as results from studies using the sources. Surface measurements require less intense sources and yield useful data on materials such as xeolites, silica gels, graphite and alumina. Experimental apparatus, data and interpretation will be discussed.

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Abstract  

The forensic activation analyst must often evaluate his own results as they relate to certain legal or moral situations, since investigative officers, and courts of law are not usually competent to make judgements of the validity or meaning of scientific data. In providing scientific evidence in court, two criteria for criminal identification must be met: (1) suspect's sample should be similar to sample found at the scene of the crime, (2) samples relared to other people in the same statistical population should not generally match that found at the crime site. When two or more specimens are submitted for comparison by NAA they will usually fall into one of three classes: (a) materials about which we have partial or inconclusive data, (c) materials with an excellent analytical data background. Ideally all cases would fall in category c; in practice, very few. Some examples of cases and/or situations that fall into these three categories in both individual and corporate investigations are given.

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