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  • Author or Editor: A. Wyttenbach x
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Abstract  

Coincidence losses may introduce a considerable error in γ-ray spectrometry and are thus a serious potential source of inaccurate activation analysis. A simple first order correction for coincidence losses can be applied by measuring the counting interval in both the true-time and in the live-time modes; the proposed equation is shown by two experiments to hold up to an integral count rate of at least 4·104 cps.

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Abstract  

Individual samples of several sets of plants (lichens, tobacco, spruce needles, grass, botanical reference materials) show highly significant correlations of Al, Fe, Hf, La, Na, Th, Ti and V with Sc. These correlations result from the terrigenous part of aerosols deposited on and measured together with the plants. The composition of this contamination is almost uniform among the different plant sets and can be approximated by the composition of the upper continental crust. The mass of the terrigenous material ranges from <1 to >100 mg/g plant. Its presence is expected to lead to concentrations of the above and of other elements that deviate substantially from those of plants without contamination. This is proved by the comparison of two sets of spruce needles, one of which was measured without and the other after removal of the aerosol.

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Abstract  

The production of201 Tl is described. Natural thallium is irradiated with protons and the induced201Pb is separated from the target by liquid-liquid extraction with diethyldithiocarbamic acid in chloroform.201Tl is separated from the mother activity (201Pb) by liquid-liquid extraction with the same reagent. The decontamination of the final product (carrier free201TlCl) is ≥5·106 from the thallium of the target and>5×104 from lead isotopes.

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Abstract  

Rare earth elements are isolated as a group from neutron activated rock samples by a new radiochemical procedure based on extraction with thenoyltrifluoracetone/phenanthroline in CHCl3. The procedure consists of three extraction steps, obviates the use of anactive carriers and gives practically quantitative chemical yields, thereby avoiding fractionation of the individual rare earths. Details of the dissolution, chemical separations and counting procedure are given togther with an analysis of BCR-1.

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Abstract  

La, Ce, Nd, Sm, Eu, Tb, Yb and Lu were determined in needles of age class 5 from 6 individual Norway spruce trees and in their soils. Measurements were done by neutron activation analysis with a group separation of the REE. Concentrations in spruce needles are among the lowest values reported for plant leaves. Concentrations show small variations between the soils, but large variations between the trees. The mean ratio plant/soil is about 5·10–3 forall REE except Ce. Needles have no Eu-anomaly and a strong negative Ce-anomaly with respect to the soil. In addition to the fractionation of the individual REE between trees and the soil, there is also a considerable fractionation between the trees.

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Abstract  

Northeastern Atlantic sedimentary rare earth element (REE) (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) phase associations among CaCO3, authigenic and lithogenic material are estimated from total sediment REE, Al, Ca, Si, Mn and Co abundances using a linear correlation technique. Phase associations were also determined using a selective chemical leaching technique specific for CaCO3+exchangeable cation, easily reducible oxyhydroxide and residual material. Results suggest that 25–50% of the REE associated with the clay material are exchangeable cations and 20–35% of the total 3+REE and 4% of the total Ce reside in coatings on the CaCO3 tests.

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Abstract  

The aerosols adhering to one year old spruce needles are investigated as for the mass deposited and as for the chemical composition. The method for the isolation of the material is presented. 33 elements are determined by neutron activation analysis. Precision, accuracy, sampling error and variation over 14 sites at the interior of woods are discussed. Chemical composition is compared to local topsoil and to local aerosols collected on filters.

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Abstract  

On the occasion of the 1970 opening of the grave of R. Brun, which is suspected to have been poisoned in 1360, samples of hair, bones and soil were taken and analysed for arsenic by neutron activation. Whereas the arsenic content of the hair was normal (0.2 to 0.3 ppm), the bones gave results of approximately 2 ppm, which is far above the value expected for healthy people (approximately 0.1 ppm). However, bones from the same grave (but not belonging to the suspected victim showed similar high values. These high values are thought to be due to an arsenic uptake from the soil and the evidence for an arsenic poisoning is under these circumstances rejected.

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