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Abstract  

NAA and ICP-MS are both highly sensitive methods for multi-element trace-and ultra-trace element determination. A comparison between analytical figures of merit of both methods is made. Both methods have specific advantages that put them beyond competition for certain applications. It is concluded that ICP-MS can replace NAA for many routine analyses. NAA remains essential as a highly reliable and accurate reference method.

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Abstract  

The program ROMOS and the assisting program RECAL are presented. These programs were designed to facilitate nuclide identification and concentration calculation in NAA using the k0-concept. For nuclide identification classical tests (energy match, decay factor) are complemented with a test of the saturation factor including the sensitivity of neutron acctivation analysis for the candidate nuclide. For nuclides emitting more than one gamma-energy the intensity of the observed peaks in the spectrum are compared. Thereby full account is taken of relative detection efficiency and true coincidence effects. Practical experience in using the interactive code shows that it is a convenient and time-saving working aid for an experienced experimenter.

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Abstract  

The concept of the effective resonance energy
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, formerly introduced as a parameter in the absolute (e.g. k0-) standardization methodology of (n, ) activation analysis, is elucidated with respect to dimensioning, accuracy and usefulness.
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Abstract  

USGS BCR-1 and G-2, NBS 1633a Coal Fly-Ash and a 7-element synthetic standard for biological material have been analysed in this work by reactor NAA, using the k0-standardization method. The analyses were performed independently in the analytical laboratories of the Institute for Nuclear Sciences (INW), Gent, and the Central Research Institute for Physics (KFKI), Budapest. This procedure allowed not only a comparison with the specified data or with other published values, but enabled a check of the consistency of our own results obtained in largely different experimental circumstances. As concluded the k0-standardization method combines general versatility (with respect to irradiation and counting conditions) with good accuracy, while keeping the experimental work as simple as possible. Since the k0 method is a computer-oriented technique, a FORTRAN IV program was designed and applied on a VAX 11/780 machine.

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Abstract  

Isotopic abundance values for50Cr,58Fe and109Ag and the absolute gamma-intensities for51Cr,59Fe and110mAg were evaluated. These evaluated data, together with experimental k0-determinations (i.e. from the
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\begin{gathered} {}^{5 0}Cr(n,\gamma )^{5 1} Cr; \sigma _0 = (15.2 \pm 0.2) barn [cf.:15.8 - 16.0] \hfill \\ {}^{5 8}Fe(n,\gamma )^{5 9} Fe; \sigma _0 = (1.31 \pm 0.03) barn [cf.:1.14 - 1.16] \hfill \\ {}^{1 0 9}Ag(n,\gamma )^{1 1 0 m} Ag;\sigma _0 = (3.89 \pm 0.05) barn [cf.:4.4 - 5.0] \hfill \\ \end{gathered}$$ \end{document}
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Abstract  

The present paper deals with the experimental determination and the critical evaluation of Qo, the ratio of the resonance integral (Io) to the 2200 m.s–1 cross-section ( o) for 57 analytically interesting (n, ) reactions, including a revision and updating of formerly published results for 13 isotopes. Full account is given for deviations from the ideal epithermal neutron flux distribution. The Budapest-Gent cooperative determinations, yielding parallel but independent results, lead to recommended Qo-values with an average uncertainty as low as 3%. Finally, with the aid of independently evaluated or measured o-data, a list of recommended Io-values is given.

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Abstract  

When making use of some single comparator or absolute standardization methods in reactor neutron and in epicadmium neutron activation analysis, the knowledge of the effective resonance energy (
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) is essential to correct for the effect of the nonideal epithermal flux distribution on the analysis result.
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can be calculated from neutron resonance data, but when these are incomplete, not accurate or even not known at all, experimental determination should be considered. Such a method, providing both
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and the resonance integral to 2200 ms–1 cross-section ratio (QO), is described in this paper. Results are given for 11 isotopes.
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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  

After critical evaluation of a number of existing standardization methods a new approach introducing generalized k0-factors was suggested in 1975 for use in (n, γ) reactor neutron activation analysis (RNAA). In order that the new method could soon be applied competitively in actual analytical work a cooperation between the Activation Analytical Laboratories of the Central Research Institute for Physics (KFKI), Budapest and the Institute for Nuclear Sciences (INW), Gent was established to determine the k0 and other related nuclear data (Q0, T1/2, Ēr, etc.) with a high accuracy, to develop procedures for monitoring essential irradiation and measuring parameters (Φse, α, ∈p,
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, etc.) as well as to share experiences when applying the method. This paper summarizes the main results of this cooperative work obtained in the last five years. The current status and recent developments in the k0-method are reviewed and a “Status and Request List” compiled from more than a thousand surveyed nuclear data on about 150 analitically important (n, γ) reactions in being prepared to suggest new or refined measurements and to prevent the use of unreliable data.
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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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