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.
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 Φth/Φe ratios in the 20<Φth/Φe<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
(Φth/Φe>100) channels. The Io/σth-values for the mentioned Zr isotopes have been experimentally determined and compared with previously published data.
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.
Authors:F. de Corte, A. Simonits, A. de Wispelaere, and A. Elek
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.
Authors:G. Molnár, ZS. Révay, Á. Veres, A. Simonits, and H. Rausch
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.
Authors:F. De Corte, A. Simonits, A. De Wispelaere, and J. Hoste
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.
Authors:F. De Corte, A. Simonits, and A. De Wispelaere
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.
Authors:L. Moens, F. De Corte, J. Hoste, and A. Simonits
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.
Authors:A. Simonits, F. De Corte, L. Moens, and J. Hoste
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 (Φs/Φe, α, ∈p,
, 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
Authors:L. Szentmiklósi, Zs. Révay, T. Belgya, A. Simonits, and Z. Kis
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.