Authors:M. Janssens, B. Desmet, R. Dams, and J. Hoste
Owing to the high ratio of resonance integral to thermal neutron activation cross-section of238U, a 5 min epithermal neutron irradiation under cadmium shielding, followed by measurement of the 74 keV photopeak of239U with a high resolution low-energy photon Ge(Li) detector, allows the fast determination of uranium in aerosols collected
on a Whatman 41 cellulose filter. Uranium blanks of the cellulose filter paper require correction and limit the sensitivity.
Simultaneously the concentrations of the elements cobalt, bromine, antimony and indium can be determined. In Belgium, the
uranium concentrations of the aerosols were found to be constant and comparable to the uranium contents of rocks.
Authors:A. Simonists, F. De Corte, A. De Wispelaere, and J. Hoste
In order to establish more accurate nuclear data for the zirconium isotopes94Zr and96Zr, joint experimental work has been conducted in three different reactor types. After carefully calibrating the neutron spectra in the irradiation channels used, nuclear constants k0 and Q0 were remeasured and found to be
The relevant effective resonance energies
. The epithermal neutron shielding factor Ge has been experimentally determined as a function of foil thickness. The results gave Ge(94Zr)=0.983 (±0.3%) and Ge(96Zr)=0.973 (±0.4%) for the most frequently used 0.125 mm foil thickness. Finally the half life of the97Zr isotope has also been remeasured to give T1/2(97Zr)=16.744±0.011 h with 1 limit.
Authors:F. De Corte, L. Moens, A. Simonits, and J. Hoste
A best choice from literature was made of the isotopic abundance values for64zn,112Sn and174Yb, and of the absolute gamma-intensities for65Zn,113mIn and175Yb. From these data and from activation method experiments, the following 2200 m·s–1 cross sections were determined:65Zn(n, )65Zn;
0=(0.726±0.0007) barn [cf. literature 0.76–0.78 barn];112Sn(n,)113(m)Sn;
0(0.91 m+g)=(0.539±0.011) barn [cf. literature 1 barn];174Yb(n,)175(m)Yb;
0(m+g)=(130+4) barn [cf. literature 65 barn].
Authors:R. Van der Linden, F. De Corte, and J. Hoste
In this second part the list of resonance integrals is completed with 63 values for (n, γ) reactions mainly from the second
part of the periodic system. The resonance integral for (n, fission) of235U is included as well as thermal and epithermal self-shielding curves for the elements Sm, Eu, Gd, Dy and Cd.
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:C. Vandecasteele, J. Dewaele, J. Hoste, R. De Doncker, F. Vangaever, and J. Vanhumbeek
Carbon is determined in gold layers electroplated on brass, by deuteron activatin analysis using the12C/d, n/13N reaction. The results range from 2 to 1300 g.g–1 and the relative standard deviation from 0.9 to 13%. It is quantitatively shown that the hardness of the gold increases with the carbon concentration and that the carbon concentration decreases with increasing plating temperature and increases to a certain limit with the plating current density.
Authors:J. Versieck, J. Hoste, L. Vanballenberghe, A. De Kesel, and D. Van Renterghem
The paper describes the collection and preparation of a second generation biological reference material (human blood serum) with trace element levels closely approximating those in real human blood plasma or serum samples.
Authors:L. Moens, P. Roos, J. De Rudder, J. Hoste, P. De Paepe, J. Van Hende, R. Marechal, and M. Waelkens
In 94 marble samples from 4 quarry districts in Italy (Carrara) and Turkey (Proconnesus, Dokimeion, Usak), minor and trace elements were determined by instrumental neutron activation analysis (INAA) and atomic absorption spectrometry (AAS). The maximum size of the calcite grains (MGS) of the rocks was measured in thin section. For 16 elements considered in this work, the concentration ranges show important inter-district overlaps; this also applies to the maximum grain size. However, the application of cluster analysis, using selected attributes, allows one to discriminate every pair of districts; 90 samples are classified correctly in all classification dendrograms.
Authors:A. Simonits, F. De Corte, T. Nimr, L. Moens, and J. Hoste
The present paper deals with the experimental determination and the critical evaluation of Qo, the ratio of the resonance integral (Io) to the 2200 m.s–1 cross-section (
o) for 57 analytically interesting (n, ) reactions, including a revision and updating of formerly published results for 13 isotopes. Full account is given for deviations from the ideal epithermal neutron flux distribution. The Budapest-Gent cooperative determinations, yielding parallel but independent results, lead to recommended Qo-values with an average uncertainty as low as 3%. Finally, with the aid of independently evaluated or measured
o-data, a list of recommended Io-values is given.