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  • Author or Editor: A. Simonits x
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Abstract  

k0-Factors and related nuclear data are tabulated for 112 radionuclides of interest in (n, ) reactor neutron activation analysis. Whenever relevant, critical comments are made with respect to the accuracy of literature data for e. g. isotopic abundances, half-lives, absolute gamma-intensities and 2200 m · s–1 (n, ) cross-sections. As to the latter, a comparison is made with the values calculated from the experimentally determined k0-factors, by introduction of selected literature data for the input parameters.

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Abstract  

A critical evaluation of different comparator methods is given. The method based on experimentally-determined and convertible comparison factors (k) is considered to be the most suitable for general use. An alternative method is proposed, introducing generalized k0 factors which are independent of irradiation and measuring conditions. This approach combines the simplicity of the absolute methods with nearly the same accuracy attained by the relative ones. It is suggested that k0 factors be compiled in all cases when using single-comparator methods, to allow a continuous re-evaluation.

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Abstract  

Different methods for the determination of thermal-to-epithermal neutron flux ratio are reviewed and nuclear data for commonly used monitor materials and for Zr isotopes are tabulated. It is shown that the use of the94Zr−96Zr isotope pair gives significant improvement in precision while measuring Φthe ratios in the 20<Φthe<200 range. When the single comparator method is applied, the use of the94Zr isotope is suggested as a comparator with the94Zr−96Zr isotope pair for simultaneous flux ratio determination. Theoretical calculations show that the Zr comparator-flux ratio monitor gives better precision and accuracy than does Ru for two-thirds of the isotopes used for analysis in well thermalized (Φthe>100) channels. The Ioth-values for the mentioned Zr isotopes have been experimentally determined and compared with previously published data.

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Abstract  

The determination of k0-factors has been continued covering now the relevant gamma-lines of 112 analytically interesting radionuclides. Experimental details are given, and an extended tabulation is presented of complex activation decay types and the associated expression for the parameters involved in the k0-method.

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Abstract  

The present paper deals with the accuracy and applicability of the k0-standardization technique in NAA. Topics included are: user-oriented outline of the method, relevant nuclear data (k0, Q0, tc.), the non-1/E epithermal flux distribution, small detector separations and/or extended source geometries, (n, ) reactions with a Westcott-g1, primary interferences, subsequent (interrupted) irradiations, the non-constancy of the neutron flux during irradiation, and a final account of the accuracy. Although the paper is written in terms of the k0-methodology, a good deal of the considerations can be transferred to most types of single-comparator standardization.

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Abstract  

In the present paper, a tabulation is given of recommended Q0-values [the ratio of the resonance integral (I0) to the 2200 m·s–1 cross-section ( 0)] for 107 (n, ) reactions of interest in NAA, including a revision and updating of formerly published results for 57 isotopes. The values were either critically evaluated from literature, or-in the majority of cases — experimentally determined according to the Cd-ratio method, with a correction for a non-ideal epithermal neutron flux distribution. These Q0-measurements were performed at INW, Gent, at KFKI, Budapest, and occasionally at Risø. A comparison is made with results obtained by other workers or with values derived from 0's and I0's quoted in recent compilations.

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Abstract  

The restart of the recently upgraded research reactor in Budapest is foreseen at the end of this year. A number of fast, thermal and cold neutron beams will serve for research, industrial and educational activities. One of the cold neutron guide end positions will be utilized for neutron capture prompt gamma-ray activation analysis (PGAA). Further development of the PGAA method as well as new applications in environmental research, biology and medicine are planned.

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Abstract  

The γ-ray spectrum analysis code HYPERMET-PC has been significantly upgraded since its introduction in the firstk 0-Users Workshop (1992). Some aspects of the implemented procedures in the new version 5.0, such as the novel approach to handle tandem LFC spectra and the benefit of using ortho-normal polynomials for fitting efficiency curves will be outlined. Having realized the importance of quality assurance in applied γ-ray spectrometry, additional utilities have been incorporated for checking system parameters: nonlinearity, energy resolution, etc. The new Nuclide Identification routine makes the program suitable for qualitative analysis both of NAA and PGAA type.

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Abstract  

HyperLab is a new Ge gamma-ray analysis code for MS Windows, developed using object-oriented design. The novel feature of the program is the extensive use of relational database technology, which allows the efficient storage and handling of any digital data encountered in gamma-ray spectroscopy. While preserving the main concept of the predecessors (HYPERMET and its derivatives) for semi-automatic analysis of multichannel pulse-height spectra, the substantially reshaped basic routines vastly improved the stability and reliability of peak fitting. New features include the fitting of peaks with high energy tail, as well as library-directed Graphical Isotope Identification. Procedures for efficiency, nonlinearity, etc. calibrations are now highly automated. By exploiting all the benefits of MS Windows technology (point-and-click simplicity in task executions, intelligent mouse pointer, etc.) HyperLab is a versatile and user-friendly tool which the discriminating spectroscopist will find of great value.

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Abstract  

The off-line γ-counting of in-beam activated radionuclides has been explored to extend the detection capabilities of prompt gamma activation analysis (PGAA). Such combination of the prompt measurement with a subsequent decay-counting is feasible if radionuclides with half-lives of minutes or hours are produced in the sample during neutron irradiation. Thanks to the simpler spectrum and the higher counting efficiency of decay counting, both selectivity and sensitivity can be improved. The pros and cons of the proposed method have been demonstrated on a series of industry-related measurements.

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