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  • Author or Editor: S. Van Lierde x
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Abstract  

Based on recently measured k0-factors and related nuclear data, an evaluation was performed, via the `activation method', of thermal (n,) activation cross sections. It concerns 15 analytically-relevant cases with a short half-life and/or with a complex activation-decay scheme: 20F, 41Ar, 60mCo/60Co, 71Zn, 77mSe, 80mBr/80Br, 104mRh/104Rh, 109mPd/109Pd/109mAg, 110Ag, 122mSb/122Sb, 124m2Sb/ 124m1Sb/124Sb, 134mCs/134Cs, 179mHf, 199mPt/199Pt/199Au and 205Hg.

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Abstract  

In order to provide a tailored solution for the correction of the 235U interference in k0-NAA, fission k0-factors for the analytically relevant radionuclides/gamma-lines (versus gold as the comparator), are experimentally determined in four channels of the Gent THETIS reactor. A comparison is made with former data from the literature. The new evaluated results are to be implemented in the forthcoming upgrade of the DSMKayzero software package for k0-NAA.

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Abstract  

A revision is made of some activation-decay types in k 0-NAA, aiming at the removal of (1) the inconvenience that a long-lived daughter radionuclide could in some instances only be measured after complete decay of a shorter-lived mother, and (2) the simplification that in some cases the measured gamma-ray emitted by the daughter radionuclide is not significantly contributed to by the mother. In view of this, new experimental and generalized k 0's and related data [Q 0, k 0(m)/k 0(g), etc.] for some analytically relevant activation-decay cases are presented for implementation in an updated version of the "Kayzero" software package. These cases are: 60mCo-60Co, 104mRh-104Rh, 109mPd-109Pd-109mAg, 122mSb-122Sb, 134mCs-134Cs, 199mPt-199Pt-199Au. For completeness, recent data for two additional cases are also included: 80mBr-80Br, 124m2Sb-124m1Sb.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: A. Simonits, F. De Corte, S. Van Lierde, S. Pommé, P. Robouch, and M. Eguskiza

Abstract  

The k 0 and Q 0 values for 94Zr(n,)95Zr(E = 724.2+756.7 keV) and 96Zr(n,)97Zr( ) 97mNb (E = 743.4 keV) were re-investigated. The aim was to further improve the reliability of the neutron spectrum characterization (f and monitoring) in k 0-NAA, based on "bare monitor" methods with the use of these Zr radionuclides. So as to achieve this goal, experimental determinations were performed in three reactor centers: KFKI AEKI, Budapest (WWR-M reactor); INW, Gent (THETIS reactor); SCK·CEN, Mol (BR1 reactor). The results were: Q 0(94Zr) = 5.306; Q 0(96Zr) = 251.6; k 0(95Zr, 724.2+756.7 keV) = 2.000E-4; k 0(97Zr/97mNb, 743.4 keV) = 1.237E-5. This means that the newly evaluated k 0-values are about 4.7% lower than the formerly reported ones. It is also emphasized that the 97Zr half-life is 16.74 hours, contrary to the 1% higher values usually reported.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: C. Chéry, S. Herremans, V. Van Lierde, F. Vanhaecke, M. Freitas, and R. Jasekera

Abstract  

Spices were analyzed by ICP-MS for determination of the ultra-micro trace elements in the human adult, Bi, Cd, Co, Ni, Pd, Pt, Se, Sn, Te, Tl, to complement previous results obtained by INAA and by EDXRF. The spices, originating from Sri Lanka, were curry, chilli powder and turmeric powders, coriander, cinnamon, black pepper, fennel, rampeh and curry leaves, and cumin. The analytical procedure was validated by analyzing the certified reference materials NIST SRM 1572 Citrus Leaves and NIST SRM 1573 Tomato Leaves. The results indicate that spices may contribute well to the daily optimal uptake of nutrients of a human adult. The adequacy of spices as a reference material with certified ultra micro trace elements is suggested.

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Abstract  

True-coincidence summing correction is an essential element in k 0-based NAA1 and becomes important when samples are counted with a high efficiency detector. This may be the case where large detectors are used or where samples are counted in or in the vicinity of the detector in order to achieve low detection limits in conjunction with low-flux reactors. In some laboratories coincidence correction is accomplished by calculating the coincidence correction factors. Since experimental validation of the calculations will reveal only the most significant errors and is a laborious task due to the high number of radionuclides involved, three laboratories decided to compare their calculated coincidence factors. Each laboratory uses a different software package. A comparative performance analysis was made of COINCALC developed at the INW of the University of Gent (implemented in SOLCOI by DSM Research), the software of the IRI, University of Delft, the Netherlands, and the software of the Ecole Polytechnique, Montreal, Canada. The overall approach, data and algorithms were chosen independently by each institute as the software was being developed and, so, the comparison has yielded a number of interesting conclusions. A follow-up investigation of the discrepancies found will probably allow the performance of each program to be improved.

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