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- Author or Editor: C. Pineda x
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Abstract
Thin targets of rare earth fluorides were bombarded with 66 and 85 MeV protons. Measured cross sections for X-ray production agreed with PWBA calculations. Satellite X-rays from nuclear reactions were obtained for both (Z-1) and (Z+1) products from the bombardment of element Z. Interference-free sensitivities were of the order of tens of nanograms under bombardment with 1 mC of integrated charge. The technique was applied for the analysis of geological ores and standards.
Abstract
The abnormally high yields of X-rays from metal fluorides were considered to be charge related or due to the prompt gamma rays from the decay of coulomb excitation of the19F nucleus. A detailed study with singly and doubly charged helium-3 ions confirmed the exceptionally high enhancement of the metal X-rays from the fluorides, but the mechanism favoured a discharge process from charge build-up in the insulating targets.
Abstract
High resolution K X-ray spectrometry preceded by activation with deuterons is an unexplored area in the field of activation analysis. This work describes the capabilities of this technique and evaluates its analytical potential for the specific determination of transition metals in small samples. Detection of the delayed X-rays coupled with their rate of decay provided a unique indication of the target component and its concentration. Analytical conditions are demonstrated for the elements of interest and the potential for application to the general routine determination of the transition metals and some of their isotopes, is discussed.
Abstract
An exfoliated fragment of a rock painting from Lesotho was analyzed by differentiated backscatter spectrometry to obtain the paint thickness, which ranged from about 2 to 6.5 
m, and its empirical formula for stopping power calculations. Elemental composition was determined by PIXE. Fe-rich paint spots were red in color and Ca-rich ones, pinkish. Because of the chemical mobility of calcium, this paint component should become the focus to which conservation techniques should be directed.
Abstract
25 human stone samples previously analyzed by inductively coupled plasma atomic emission spectroscopy /ICP-AES/ and the IAEA Animal Bone Standard Reference Material were used to evaluate trace element analysis by PIXE. Bombardment with 4 MeV protons was used for the determination of Mn, Fe, Cu, Pb, Br, Rb, Sr as well as Ca. PIXE and ICP-AES data gave correlation factors better than 0.97 for the elements Ca, Fe, Zn, Sr and Pb.
Abstract
Potsherds from north and south of the Soutpansberg mountain range in Transvaal were analyzed by PIXE to establish possible trade patterns between the two regions, over the last thousand years. Correspondence analysis based on the content of 12 elements made it possible to distinguish pottery from the two regions, irrespective of where they were found. A model combining elemental and stylistic analysis was developed to explain both the physical movement of pots and the diffusion of ideas.
Abstract
Using 1.0 MeV protons on thick targets of zeolite pellets, aluminium and silicon were determined by PIXE. Results were compared with XRF data. The relative root mean square error was 3.7% and the results of the two methods agreed with a correlation factor of 0.991. PIXE analysis can be carried out on very small samples, while sample preparation involves minimal handling.
Abstract
The lithium content of the gem mineral, Sugilite, was determined by promt alpha spectrometry from the reaction7Li (p, α)4He with 1000 keV protons, and by proton-induced prompt photon spectrometry (PIPPS) of the 479-keV7Li, p(1,0) gamma-ray excited by 1000 and 4500 keV protons and 429-keV7Li n(1,0) gamma-ray induced by 4500 keV protons. The lithium content was found to be 3.72±0.06% by mass as Li2O. Simulated mineral matrices were used as standards.
Abstract
The split-root technique was used to study the effect of varying the growth media on the elemental content of nutrient elements in the roots of grape vines. The varieties 2-1 (R99 x Jacquez) and Sauvignon blanc (Vitis vinifera) were grown in Hoagland water culture with and without added aluminium. The elemental concentrations of Mg, Al, Si, P. S, Cl, K and Ca in the dried roots were determined by PIXE. Roots grown in Al-rich media were deficient in Mg and Ca, but enriched in Al. There was a correlation between Al and Si but the uptake differed in the two varieties.
