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  • Author or Editor: Yu. Tsipenyuk x
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Abstract  

The results of applying photoactivation for express nondestructive multicomponent analysis of apatite-nepheline, gold-bearing, polymetal and lapparite ores are presented. The experiments were carried out at the IPP microtron with bremsstrahlung of 10 to 15 MeV electrons. A setup with mixed gamma-neutron field was built and used for elemental analysis. Experiments show that such elements as P, Al, Ti, Ba, and Ce can be determined with a sensitivity of approximately 0.1 mass% and a statistical error of a few percents. These values are wholly satisfactory to modern demands of industry. Gold and silver can be successfully determined in gold-bearing ores on the level of grams per ton.

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Abstract  

Nondestructive photoactivation analysis for stoichiometry of Nb-Ge and Zr-Nb alloys, diluted antiferromagnets Mn x Zn1-x F2 and CsNi1-x F2 and CsNi1-x Mg x Br3, and high-temperature superconductors LaSrCuO has been developed at a 30 MeV microtron. It is shown that it is possible to obtain an accuracy of elemental content determination on the level of 1% or even less by using the method of internal standards. In particular, the method has been applied for inspection of the quality of single crystals grown for physical research purposes.

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Abstract  

Using extracted electron beam from the 30 MeV microtron of IPP a thermal neutron source was built for activation analysis. Combined (Ta–Pb)-target is used as a gamma-neutron converter, and high-pressure polyethylene is used as a moderator. For the purpose of activation analysis special channels of different sizes were made in the moderator, with, in particular, a large pocket of about 103 cm3 in volume for irradiation of extended objects. Detailed spatial neutron flux distribution was measured, and the neutron flux density is of the order ofn·109 n·cm–2·s–1. The set up was used for detemination of Sb, As, V, Cr, Mn, Ni, Ga, Br, Re, Cd, REE content in oil, fuel oil, petrol, gaseous condensate under normal conditions. The sensitivity of noble elements determination in non-destructed loaded boards approaches 1 mg of total mass in the assembly, and equals 0.05 ppm for Au detemination in rocks and minerals.

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Abstract  

Based on studies of variable multiplicity electron acceleration, the power-current microtron, a cyclic electron accelerator up to energies of 30–35 MeV has been developed at the Institute on Physical Problems of the Academy of Sciences of the USSR. The 1–1.5 kW electron beam of the microtron is comparable to the power output of modern linear accelerators operating at similar energies. At the same time, the microtron has a number of significant advantages, due to the simplicity of design of both accelerator and ultrahigh-frequency tract, the high efficiency of ultrahigh-frequency power utilization, good operating characteristics, strictly monochromatic electron beams (variations not exceeding ±50 keV at 30 MeV) and the possibility of continuously changing particle energy as required by the given experimental task.

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Abstract  

A solubility of nitrogen in natural basalts and synthesized albite at 1250 °C and 3 kbar was studied by -activation method based on the reaction14N(,n)13N with radiochemical separation of nitrogen by high-temperature extraction at 1800 °C. Detection limit of 0.2 g in the samples of 15–20 mg weight is obtained. The investigation originated from the study of processes of accumulation and redistribution of nitrogen in rock-forming alumosilicate melt of the Earth mantle. The dependence of nitrogen solubility on the oxygen volatility and pressure were obtained (within 1–3 kbar in the presence of IW buffer [iron(Fe)-wustite(FeO)]) and NNO (Ni–NiO), and essential effect of the composition of the initial matrix was found. Special attention was given to standards, background, interference reactions, reliability and accuracy of the results.

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Abstract  

The biokinetics of radioactive substances can be studied using stable tracers. For the highly radiotoxic actinides, for which no stable isotopes are available as tracers, the use of stable isotopes of lanthanides as chemically related surrogates has been suggested. In this work, the possibility of using activation analysis with protons, photons, or thermal neutrons for the determination of single stable isotopes of gadolinium in biological samples has been tested. All the techniques show very good linearity response, and may be considered as complementary. Whereas activation analysis with protons is recommendable for the simultaneous determination of two different isotopes, neutron and photon (gamma) activation analysis should be chosen whenever a better sensitivity or simplicity of the analysis is required.

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Abstract  

It has been shown that gamma-activation significantly extends possibilities of activation autoradiography with respect to determination of platinum group elements (PGE) in silicate samples. All PGE may be activated by bremsstrahlung with forming radionuclides having convenient half-lives for autoradiography (hours-days). Digital methods for quantitative 2D-densitometry of autoradiograph images by means of documents scanners have been developed and discussed. Approaches for increasing selectivity of analysis by means of autoradiography have been proposed and tested on the real sample containing PGE inclusions (analysis of decay kinetics while cooling, combination with gamma-ray spectrometry).

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Abstract  

Information on the biokinetics of cerium can be obtained directly from humans by using stable isotopes as tracers. Neutron, photon and proton activation analysis have all been tested as analytical techniques able to quantify different isotopes of the same element in biological fluids. The experimental conditions were optimized for Ce analysis in blood plasma samples. The performances of the different techniques have been explored. The simultaneous determination of two Ce isotopes with the required sensitivity in the order of few ppb is difficult to obtain using a single technique, and, therefore, a combination of techniques can be envisaged.

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