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Abstract  

The effective resonance energy
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\left( {\bar E_r } \right)$$ \end{document}
, a useful parameter when correcting the resonance integral for a non-ideal epithermal neutron flux distribution, can be experimentally determined by coirradiating the investigated isotope with a comparator isotope whose effective resonance energy is accurately known. The principle of the method is outlined and the error propagation functions are studies in detail. The usefulness of the
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-comparator technique is tested for a few isotopes.
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Abstract  

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].

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Abstract  

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.

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Abstract  

The isotopes97Ru,103Ru and105Ru, produced by reactor irradiation of elemental ruthenium, were applied as triple comparators in the activation analysis of rock FU-41, a basanitoid from Fuerteventura, Canary Island. The concentrations of the following elements were determined: Sm, Sc, Fe, Co, Na, La, Hf, Eu, Th and Cr. The aim of this work was the experimental control of the error theory of the multiple comparator method as well as the experimental check of the accuracy.

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Abstract  

The determination of boron in magnesium oxide using the10B/p, /7Be,10B/d, n/7Be, and10B/d, n/11C reactions is described. Lithium interferes the nuclear reactions leading to beryllium-7. Combination of a proton and deuteron irradiation, each followed by measurement of the induced beryllium-7 activity, allows a simultaneous determination of boron and lithium. The10B/d, n/11C reaction is free from nuclear interferences. The boron concentration ranges from 1.5 to 850 g g–1. The results obtained by the two methods are in good agreement.

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Abstract  

The present paper deals with the accuracy and applicability of the k0-standardization technique in NAA. Topics included are: user-oriented outline of the method, relevant nuclear data (k0, Q0, tc.), the non-1/E epithermal flux distribution, small detector separations and/or extended source geometries, (n, ) reactions with a Westcott-g1, primary interferences, subsequent (interrupted) irradiations, the non-constancy of the neutron flux during irradiation, and a final account of the accuracy. Although the paper is written in terms of the k0-methodology, a good deal of the considerations can be transferred to most types of single-comparator standardization.

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Abstract  

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
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have been recalculated using the latest BNL neutron resonance parameters yielding
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\bar E_r (^{94} Zr) = 6260 eV ( \pm 4\% ) and \bar E_r (^{96} Zr) = 338 eV ( \pm 2\% )$$ \end{document}
. 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.
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Abstract  

The comparator method, earlier published byDe Corte et al. is first discussed as well as a more practical transformation, which delivers directly the flux ratio, using a relative technique. For each part of the multiple comparator method (MCM) separately, a discussion of error multiplication is worked out and at the end a general formula to calculate the total error change is derived.

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Abstract  

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.

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