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  • Author or Editor: A. Pillay x
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Abstract  

Enhanced yields from CHIX studies on non-conducting samples have demonstrated conclusively that such yields are exceptionally high when compared to PIXE at low incident particle energies. This was confirmed with low energy14N+,16O+ and20Ne+ ions whose X-ray production crosssections are negligibly small for PIXE yields. In particular, a combination of low incident energies and high X-ray yields could be useful for XSQR investigations and elemental studies with low energy accelerators. Furthermore, extended studies on pure metal targets revealed that the PIXE yield could be improved by insulating the targets thus making them suitable to produce the CHIX yield under identical experimental conditions. This paper discusses the complementary and competitive features of PIXE and CHIX.

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Abstract  

Elemental analysis of ancient artefacts is of considerable benefit to the field of Archaeology and of general interest to earth scientists. Several techniques are currently available for this purpose, and in this paper the capabilities of PIXE (Particle Induced X-ray Emission), XRF (X-ray Fluorescence) and ICP-MS (Inductively Coupled Plasma - Mass Spectrometry) were evaluated to establish which of these instrumental methods was best suited especially for routine on-line usage. The elements of interest discussed in this paper are useful in archaeological provenance studies.

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Abstract  

Sensitive methods of elemental analysis have been developed using charged-particle beams. These techniques are usually insensitive to the effects of outer-shell electrons and provide little or no information on chemical bonding. The past 50 years has seen wide applications of various accelerator-based methods in different areas of analysis. This paper reviews the development and major advances of a variety of ion-beam techniques and their impact in analytical studies.

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Abstract  

High resolution (K) X-ray spectrometry preceded by activation with fast neutrons, neutrons from an isotope-source, and charged particles, is a novel development in the field of activation analysis. This paper describes the capabilities of these techniques and evaluates their analytical potential for the specific determination of the rare earths and Platinum Group Elements (PGE's) in small samples. The investigation took the form of a feasibility study which relied heavily on the low energy sensitivity of the detector used. Detection of the delayed X-rays was achieved with a 100 mm2 Ge detector whose ability to produce optimum photopeak-to-noise ratios formed the basis exploited in this investigation. Analytical conditions are demonstrated over a range of concentrations for the elements of interest and the potential of the technique for application to the general routine analysis of the rare earths and PGE's are discussed.

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Abstract  

The role played by national institutes and universities in the education, training and research in South Africa, is described. In addition, details are given of the nuclear science courses available at technikons for students in chemistry, physics, nuclear technology, and analytical and medical applications.

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Abstract  

An assessment was made of the analytical potential of the exoergic reactions on boron, induced by3He+ beams. Possible interferences from C, N and O were studied. Gamma-rays originating from (3He, n), (3He, d), (3He, d), (3He, ) and Coulomb excitation were identified. Possible practical applications in boron studies are indicated.

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Abstract  

A recently discovered phenomenon of excessively high X-ray production is discussed. The high yield is attributed to the build-up of potential on non-conducting targets irradiated with accelerated ion beams, and the subsequent discharge. Ion-beams of1H+,1H2 +,2H+,2H2 +,3He+,3He2+,4He+,14N+,14N2+,16O+ and20Ne+ were used. A new mechanism of X-ray excitation is proposed. The increased X-ray fluxes produced by this process are suitable for analytical applications of high specificity. The mechanism of excitation associated with the process, factors affecting the high X-ray yields, applications and a general overview of the studies undertaken with the various ion beams are given.

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Abstract  

Earlier work on Charge Induced X-rays (CHIX) was extended to include the X-ray energy region between 0.70 to 4.0 keV. Protons of 700 keV, and1H 2 + ion beams of equivalent proton energies in the range 350–450 keV were used to produce enhanced yields of L and MX-rays from a suitable selection of highly compacted non-conducting samples. Enhancement factors are given and possible applications are mentioned.

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Abstract  

A novel technique for the determination of Pt and Au at low concentrations is described. The method involves /K/ X-ray spectrometry preceded by fast neutron activation of the stable isotopes of the elements of interest. A full appraisal of the technique is presented for the analysis of small powdered samples. The sensitivity was optimized by employing a detector that was particularly effective at energies below 150 keV. The investigation formed the basis of a feasibility study which was utilized to establish if the application could be developed for the routine off-line determination of Pt and Au. We show that the method does not necessarily depend on the sample matrix, and that it proves to be a strong rival to conventional activation analysis.

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Abstract  

Previous studies reporting “abnormally” high X-ray yields from non-conducting targets under bombardment with low energy ion-beams were considered to be charge related. These studies were extended to metal targets surrounded by insulating material. Differences and similarities are discussed.

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