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- Author or Editor: M. Wasek x
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Abstract
In this work the term 
blank
signifies total radiation of the sample analyzed except that the element to be determined (analyte) is absent. On the basis of the evaluation of the blank components (nuclear and spectral interferences, air-nitrogen between grains etc.), a semiempirical formula for calculating the nitrogen content in plant grain samples is proposed. The reliability of the results obtained with the use of this formula has been demonstrated for five sorts of seeds (rye, wheat, barley, broad bean and soybean) which have been analyzed by the Kjeldahl method and 14 MeV neutron activation analysis, respectively.
Abstract
It was shown that the peak intensities in a 
-ray spectrum measured with pile-up rejector are a function of the lower level discriminator settings. There is some systematic shift between the peak areas in spectra taken with pile-up rejector on and off. Explanation of this shift is given by using the 1332 keV60Co peak as an example.
Abstract
It has been recognized that the intensity of a high-energy peak in a gamma-ray spectrum measured by means of a multichannel pulse height analyzer, coupled to a Wilkinson type analog-to-digital converter (ADC) and through the necessary electronics to a Ge(Li) detector, is a function of the threshold of the lower level discriminator (LLD) in the ADC. The LLD effect has been observed for several conventional analyzers and various total count rates up to 6·104 cps. The results of the measurements carried out both in the live time mode and in the clock time mode are presented and the systematic errors which can be introduced by the LLD effect are discussed.
Abstract
Distribution coefficients of 14 elements between LIX 70 in toluene and aqueous 1M NaNO3 solution containing varying concentrations of HCl or suitable buffer, respectively, were determined by batch equilibration. It was shown that very selective separation of Cu from other elements can be achieved on columns with LIX 70 supported on Bio-Beads SM-1. Highly accurate and precise method for the determination of trace amounts of Cu in biological materials was devised by combining NAA with extraction chromatography. Results of copper determination in NBS 1570 /Spinach/, IAEA H-4 /Animal muscle/ and IAEA V-8 /Rye flour/ are presented.
Abstract
A highly accurate and precise procedure deserving the name of 
definitive method
has been devised for the determination of copper in biological materials. The method is based on combination of neutron activation and very selective and quantitative post-irradiation separation of copper from other radionuclides by extraction chromatography, using columns with LIX 70 on Bio-Beads SM-1, followed by gamma-ray spectrometric measurement. All potential sources of errors were carefully examined and eliminated or appropriate corrections were introduced into the procedure. The method contains several warning mechanisms safeguarding against making gross errors. Limit of detection for rather short irradiation time (tir
1 h) (which enables radiochemical work without sophisticated shielding) amounts to 15 
g/kg. Results for copper concentration in several NBS, IAEA and other certified reference materials are presented and a new recommended value for IAEA's Milk Powder (A-11) is proposed.
Abstract
The sources and nature of dead time of the multichannel analyzer (MCA) coupled to a Wilkinson type analog-to-digital converter (ADC) were examined. A dead time model based on two types of dead time, non-extended (nonparalysable) and extended (paralysable), is suggested. Special attention is paid to an extended type imposed by the pulse amplufier and the lower level discriminator in an ADC.
