Authors:F. De Corte, L. Moens, A. Simonits, K. Sordo-El Hammami, A. De Wispelaere, and J. Hoste
A description is given of the systematic errors which can be introduced when applying absolute or comparator standardization
techniques to RNAA or ENAA at irradiation sites with a deviating 1/E1+α epithermal neutron flux distribution. A simple correction formula for a≠0 is presented and a survey is given of the present
state-of-the-art for experimentala-monitoring and for the calculation or experimental determination of the effective resonance energy Ēr. Extensive error calculation leads to the conclusion that, with careful selection ofa monitors and of the nuclear data involved, the rather large errors (∼10% or more) are reduced, after correction fora, to uncertainties of about 2%.
Authors:F. De Corte, K. Hammami, L. Moens, A. Simonits, A. De Wispelaere, and J. Hoste
Some methods for the experimental α-determination in the 1/E1+α epithermal reactorneutron spetrum are critically compared with respect to their accuracy and precision. The analysis is based
on the error propagation theory. Besides the general formulae numerical examples are elaborated for specific conditions in
the Thetis reactor (Gent) and the WWR-M reactor (Budapest).
Authors:R. Van der Linden, F. De Corte, P. Van den Winkel, and J. Hoste
The resonance integrals for 59 isotopes were determined by neutron activation in reactor Thetis. The irradiations were carried
out with and without Cd cover. The ratios of the thermal to epithermal fluxes were calculated from the Cd ratio of a Au monitor.
From the induced activities in 36 elements, measured by means of γ-spectrometry with Ge(Li) and NaI(Tl) detectors, the values
of I0/σth were obtained.
Authors:A. Simonits, L. Moens, F. De Corte, A. De Wispelaere, A. Elek, and J. Hoste
ko-factors of 35 isotopes used in reactor neutron activation analysis were measured with a high degree of accuracy (1–2%). To
minimize systematic errors, measurements were carried out using different reactor types, irradiation conditions (18 < Φs/Φe), Ge(Li) detectors, sample detector geometry, etc. Analyst-oriented tabulations including all necessary nuclear data, “best
values”, as well as recommended ko-values are given to facilitate analytical work with the new method. Some practical aspects as well as limitations of the
ko-method are also outlined together with the applied neutron flux and cross-section conventions.
Authors:L. Moens, F. De Corte, A. De Wispelaere, J. Hoste, A. Simonits, A. Elek, and E. Szabo
Recommended k0-factors and related nuclear data for use in (n, ) activation analysis are given for 72 isotopes. In addition the basic nuclear constants and experimental parameters needed in the k0 standardization method are reviewed. For convenient data reduction, computer programs were developed.
Authors:L. Moens, F. De Corte, A. Simonits, Lin Xilei, A. De Wispelaere, J. De Donder, and J. Hoste
A new method is presented to calculate with improved accuracy the absolute peak efficiency of cylindrical Ge and Ge(Li) detectors
for point, disk and cylinder sources, positioned at any source-detector distance. Moreover attention was paid to true-coincidence
effects. The method is extensively tested and applied for the analysis of reference materials. The accuracy turned out to
be 3% or better.