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  • 1 Ghent University Lab. Anal. Chem., Inst. Nucl. Sci. Proeftuinstraat 86 B-9000 Gent Belgium
  • | 2 Gent University, Institut voor Nucleaire Wetenschappen Laboratory of Analytical Chemistry, Institute of Nuclear Science (INW) Proeftuinstraat 86 B-9000 Gent Belgium
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Abstract  

The reloading of research reactor Thetis (INW, Gent), in April 1996, involved the re-calibration of the irradiation facilities used for k0-NAA. In some channels, the values of the re-measured parameters f and a significantly deviated from the ones before reloading, and the effect of this on the concentration results is demonstrated. Some additional experimental work was done in two irradiation facilities, one well-thermalized and another with a hard neutron spectrum, in order to examine the behavior of a with neutron energies up to about 60 keV. This study was performed in the context of a lasting controversy regarding the accuracy of the k0 and Q0 values for the 95,97Zr-isotopes, especially in view of the high 94Zr(n,g) effective resonance energy. In the irradiation channels under consideration, no evidence was found of a versus energy dependence