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Abstract  

The isotopes97Ru,103Ru and105Ru, produced by reactor irradiation of elemental ruthenium, were applied as triple comparators in the activation analysis of rock FU-41, a basanitoid from Fuerteventura, Canary Island. The concentrations of the following elements were determined: Sm, Sc, Fe, Co, Na, La, Hf, Eu, Th and Cr. The aim of this work was the experimental control of the error theory of the multiple comparator method as well as the experimental check of the accuracy.

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Abstract  

For 13 isotopes, the resonance integral to thermal crosssection ratio was studied. The results of two different methods, applied in two different laboratories, are compared. One method consists in a direct determination of I00-values from Cd-ratio measurements, the other is based on the evaluation of literature data, using accurately determined k0-factors from two irradiation channels with largely different thermal-to-epithermal flux ratios.

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Abstract  

The infinite dilution resonance integrals of fifteen (n,γ)reactions leading to the production of short-lived radioisotopes were determined. The irradiation parameters were checked by comparing the results of different methods and the measuring equipment was carefully controlled.

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Abstract  

By comparison of experimental k0-factors, determined in reactor positions with greatly different thermal-to-epithermal neutron flux ratios, and by comparison of experimentally determined and theoretically calculated k0-factors, it is possible in some cases to select best values from literature data for (n, γ) activation cross-sections and for absolute gamma intensities. This is demonstrated for97Zr,95Zr,56Mn and65Zn.

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Abstract  

A method is described for the determination of Au, Pt, Pd, Ag and Ir in two atmospheric aerosol samples, namely in Ghent and in the Milanese intercomparison sample. After neutron irradiation the samples are fused with Na2O2. Gold is extracted with ethylacetate, Pt precipitated as (NH4)2PtCl6 Pd as dimethylglyoximate, Ag as chloride and Ir separated by anion-exchange adsorption and batch extraction. Ge(Li) gamma-spectrometry is applied for all determinations. The concentrations in ng·g−1 in the samples are respectively: Au: 49 and 3000; Pt: below 100 for both samples; Pd: 7 and 28; Ag: 6000 and 14 000; Ir: 2.5 and 1.3.

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Abstract  

The effective resonance energy
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, a useful parameter when correcting the resonance integral for a non-ideal epithermal neutron flux distribution, can be experimentally determined by coirradiating the investigated isotope with a comparator isotope whose effective resonance energy is accurately known. The principle of the method is outlined and the error propagation functions are studies in detail. The usefulness of the
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-comparator technique is tested for a few isotopes.
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Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Van Schandevijl, R. Van Grieken, and J. Hoste

Abstract  

The half-life of28Al was redetermined on aluminium samples of different origin. Three different counting techniques were applied. The availability of highly purified samples (up to 99.9999%), the use of very fast electronic counting equipment and a complete automatisation allowed a good precision to be obtained in the final result of 2.2405 min.

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Abstract  

The comparator method, earlier published byDe Corte et al. is first discussed as well as a more practical transformation, which delivers directly the flux ratio, using a relative technique. For each part of the multiple comparator method (MCM) separately, a discussion of error multiplication is worked out and at the end a general formula to calculate the total error change is derived.

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Abstract  

The determination of boron in magnesium oxide using the10B/p, /7Be,10B/d, n/7Be, and10B/d, n/11C reactions is described. Lithium interferes the nuclear reactions leading to beryllium-7. Combination of a proton and deuteron irradiation, each followed by measurement of the induced beryllium-7 activity, allows a simultaneous determination of boron and lithium. The10B/d, n/11C reaction is free from nuclear interferences. The boron concentration ranges from 1.5 to 850 g g–1. The results obtained by the two methods are in good agreement.

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