Authors:F. De Corte, M. Dejaeger, S. M. Hossain, D. Vandenberghe, A. De Wispelaere, and P. Van den Haute
Recently, in our laboratory an intercomparison was made of methods for the annual radiation dose determination (assessed from direct radiation counting and/or from the measurement of the K, Th and U contents) applied to luminescence dating of loess and sand sediment, whereby the emphasis was put on their precision and accuracy. Although these properties are important, the duration of the measurement is also a practically relevant aspect. Indeed, direct alpha, beta and gamma-counting can last a week or more, and the determination of K, Th and U via NAA can take up to three weeks to enable proper gamma-ray spectrometry of the long-lived 233 Th/233Pa. Therefore, in the present work the performance of k0-based epiCd-NAA (ENAA, with irradiation under a cadmium cover) when applied to sediments is compared to k0-NAA. As concluded, with the use of k0-ENAA the analysis turnaround time could be considerably reduced from ~3 weeks to ~ 2.5days, while maintaining satisfactory accuracy, precision and determination sensitivity.
Authors:F. de Corte, K. Masumoto, A. De Wispelaere, and F. Bellemans
A dedicated NAA calibration method was developed for the determination of the neutron spectrum monitor elements Co, Au and Lu in alloyed wires and foils, with an accuracy of better than 1%. The method does not require quantitative micropipetting for preparing the standards, and leads to vanishing errors caused by flux inhomogeneities and by differences in counting geometry and gamma attenuation. Its performance was tested by analysing various NIST, IRMM and RX aluminium-based materials with certified or specified Co, Au or Lu content.
In order to calculate coincidence correction factors when measuring with a low-energy photon detector (LEPD), algorithms were developed for the description of the summing-out probabilities taking into account -LX in addition to - and -KX true-coincidences, where KX and LX can originate from internal conversion and electron capture. The accuracy of the calculation procedure is experimentally checked. The work presented here is part of an extension of the NAA k0-standardization to counting in a LEPD.
Authors:M. Freitas, F. De Corte, M. Gouveia, M. Prudêncio, and J. Cabral
The Ree contents in lichens and plants determined by k0-standardized NAA with LEPD and HPGe are compared. We obtain similar values for Sm, Eu, Tb and Yb and better values for Ce and Nd by using LEPD Besides, LEPD allows the determination of Gd, Tm and Lu. The study of REE concentrations in the neighbourhood of two coal power stations show that: i) in the station under construction (C. T. Pego), the index of accumulation of each REE by the lichens and olive tree leaves is identical in two sampling loci where the soils have different REE concentration; and ii) in the station in operation (C. T. Sines), the REE contents in the soils is identical and the differences observed in the lichens and wild terrestrial plants are most probably due to the fly-ashes emmission from the station.
-values are calculated, and the correction procedure for the cascade coincidence effects is established by calculation of
the correction factor COI for five 130I γ-rays (418.0, 536.1, 668.5, 739.5, and 1157.5 keV).
Authors:Bangfa Ni, Pingsheng Wang, Huiling Nie, Shuyuan Li, Xuefeng Liu, and Weizhi Tian
A PC controlled automatic INAA system is briefly introduced. The unique features of the system in software, hardware, and quality control procedures are described. Major performances are given to show the analytical quality and productivity of the system.
The determinations of trace elements in tissues of herons are of great interest in order to evaluate environmental contamination.
As the herons are at the top of the food chain they tend to accumulate high concentrations of contaminants in their tissues.
Besides, the effects of pollution are also severe for this species, endangering the survival and reproduction of bird populations.
In the present study, concentrations of the trace elements Br, Co, Cs, Fe, Rb, Se, and Zn were determined in livers from Great
Egret (Ardea alba) species. The liver samples were those obtained from the adult specimens found dead in the metropolitan region of São Paulo,
SP, Brazil. The liver samples were ground, freeze-dried and the elements were determined by the method of neutron activation
analysis. The elemental concentration obtained in livers of these species showed wide variations depending on the element.
Comparisons made between our results with literature data indicated that element concentrations obtained for herons from metropolitan
region of São Paulo are higher or at the same order of magnitude of those obtained for specimens from polluted areas. Comparisons
made between the results obtained for different genders of herons by applying nonparametric Mann–Whitney U test at the significance level of 0.05 indicated that female herons present Co and Se concentrations lower than those from
Authors:R. López-Valenzuela, J. López-Palacios, M. Jiménez-Reyes, G. Cataño, and D. Tenorio
Thirteen Teotihuacan-style ornaments of an incense burner were studied. Ceramic pastes, pigments and mica were analyzed by
neutron activation, X-ray diffraction and scanning electron microscopy. Elemental (Sc, Cr, Fe, Co, Rb, Cs, La, Ce, Nd, Sm,
Eu, Tb, Yb, Lu, Hf, Th and U) and statistical analyses of ceramic-body data showed that these pieces were made from the same
raw material, which is chemically different from the fine orange ceramic of Teotihuacan. Montmorillonite and the classical
components of sand were the minerals identified in the ceramic pastes. The white pigment contained calcium, titanium and aluminium,
the yellow pigment was ocher, and the red pigment was a mixture of red ocher and cinnabar, the binder of the pigments being
clay. Exoskeletons of diatoms and locust ootecs were found in the pigments. Mica was identified as biotite, identical with
that coming from Monte Alban Oaxaca. We wish to undertake a historical reconstrution of these ornaments based on archaeometric
and literature data.
Authors:S. Metairon, C. Zamboni, L. Kovacs, F. Genezini, N. Santos, and E. Vilela
Neutron activation analysis has been used to determine Br, Ca, Cl, K, Mg and Na concentrations in whole blood of patients
with chronic kidney disease (CKD) as well as in whole blood of normal individuals (control group). The dependence of the elements
concentration in function of sex, age, time and type of treatment were investigated. The similarities and differences between
healthy individuals and CKD are discussed.
Authors:F. De Corte, A. De Wispelaere, R. van Sluijs, D. Bossus, A. Simonits, J. Kučera, J. Frána, B. Smodis, and R. Jaćimović
At the Special Sessionk0
of the MTAA-8 (Vienna, 1991), and later on at the Intemationalk0 Users Workshop-Gent (1992), progress was reported with respect to the development and use of computer codes in order to mould thek0-standardization of neutron activation analysis into an effective working instrument. Among others, this resulted in the software package KAYZERO for PC DOS, which was designed and distributed by DSM Research (Geleen, NL), and which is based on thek0-methodology, algorithms and nuclear data file developed and created at the INW (Gent, B) and the KFKI (Budapest, H), the traditional
k0-centres. One of the most recent initiatives is a project in the framework of the COPERNICUS programme of the Commission of the European Union. It uses the synergism of a Joint Research Project to give an impulse to the exploitation of KAYZERO-assisted NAA as a manageable and competitive analytical tool in industry and environmental sanitation in Hungary, the Czech Republic and Slovenia. An outline is given of the strategy worked out in this JRP, emphasizing the procedures applied in the three institutes for the calibration of their irradiation facilities and Ge-detectors, quality control and assurance procedures following the implementation of the method, and the identification and tackling of the practical analytical problems which are of relevance to the Central European partner countries.