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  • Author or Editor: Á. Veres x
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Abstract  

Photon activation analysis has been developed to determine the selenium content. The method can be applied for continuous monitoring of the addition of selenium to animal food-stuff.

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Abstract  

An analytical method is described for the determination of erbium in rock samples using γ-rays from a24Na radiation source. A detection limit of 1 μg erbium in 10 g samples can be achieved using a 200 Ci24Na source. The time required for a single analysis is about 5 minutes.

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Abstract  

An analytical method has been developed for the determination of Se, Br, Sr, Ag, Cd and In in some mixtures applying (γ, γ′)-type reactions. This method provides a high degree of selectivity and precision if the concentration of the element in the sample is a few per cent or more. Using an 80-kCi60Co gamma-radiation source, as low as 0.002–0.14% impurities could be determined in 50-g samples; this corresponds to 1–70 mg quantities of the particular elements.

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Abstract  

Silver and gold were analysed in coins and medals by inelastic gamma-scattering reaction. The irradiation was performed with a 740 TBq (20 kCi)60Co source. After irradiation the isomer activities were measured with a well type NaI(Tl) scintillation counter and evaluated by means of a software program.

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Abstract  

The activation of indium by gamma-ray source through absorption of photons of resonance energy and the threshold energy (appearance energy) determination in indium compounds as well as some results of hot atom chemistry studies of indium compounds and of implantation with indium ions are described.

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Abstract  

The restart of the recently upgraded research reactor in Budapest is foreseen at the end of this year. A number of fast, thermal and cold neutron beams will serve for research, industrial and educational activities. One of the cold neutron guide end positions will be utilized for neutron capture prompt gamma-ray activation analysis (PGAA). Further development of the PGAA method as well as new applications in environmental research, biology and medicine are planned.

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The concentration (in mg kg–1 fresh weight) of two main hydroxamates, 2,4-dihydroxy- 7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), and their temporal changes were simultaneously investigated using HPLC analysis in the leaves and roots of five Pioneer® maize (Zea mays L.) hybrids to select hybrids with higher hydroxamate contents. Although significant differences were found among hybrids in leaves, youngest leaves and roots, none of them showed unambiguously higher hydroxamate contents. However, the age of the organs and the plants significantly affected hydroxamate content. DIMBOA content of leaves decreased with increasing organ and plant age. DIBOA content varied among the hybrids, but generally decreased in the initial phase and then increased. In the roots, DIMBOA content decreased during the 21-day study and although DIBOA content did not show a clear temporal tendency, differences among hybrids were detected. According to current results, hydroxamate content temporally decreases in hybridspecific patterns, which should be considered when establishing a proper sampling time frame.

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Abstract  

The99Tc (, 3n)96Tc and99Tc (, 4n)95Tc reactions were studied by irradiation of target99Tc with bremsstrahlung from the linear electron accelerator of Tohoku University, up to 50 MeV -energy. The resulting96Tc (4.3 d) and95Tc (20 h) activities were determined by -spectrometry. The -flux was monitored by the99Tc (, )99mTc reaction. Metallic copper and gold foils were used as additional flux monitors in front of and behind the samples. Their measured radioactivity was utilized for normalizing bremsstrahlung flux calculations, in order to determine reaction cross sections. Cross sections were also determined theoretically, performing calculations in the framework of a neutron cascade evaporation model. Above the (, 3n) and (, 4n) threshold energies the neutron emission channel was supposed to be the only open channel for deexcitation following photoabsorption. The preeguilibrium contribution was considered negligible. The experimental results obtained for the integrated cross section at 30 and 50 MeV fit reasonably well the calculated curves.

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Abstract  

A new nuclear excitation process,99Tc (, )99mTc reaction, was applied for the first time to radioactivation analysis of technetium. Bremsstrahlung irradiation of99Tc samples gave the reaction product99mTc which emits -ray measurable with ease by a semiconductor detector. The production rate of99mTc per g99Tc was linearly correlated with the flux of bremsstrahlung. The detection limit of99Tc was estimated to be nanogram order (0.63 Bq99Tc) under the optimum irradiation condition. Possible interference by100Ru(, p)99mTc reaction was also studied, which could be discriminated from the (, ) reaction by simultaneously occurring98Ru (, p)97Ru reaction.

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Abstract  

A liquid scintillation counting technique was applied to measure the isotope103mRh /half life = 56.12 min/ which is difficult to detect because its -ray is of low energy and low emission probability. Tris-/2,4-pentanedionato/ rhodium /III/ /Rh/ acac/3/ was irradiated with bremsstrahlung of accelerated 3.2 MeV electrons by LINAC. The method has given a reliable calibration curve for the determination of103mRh radioactivity below Rh/acac/3 concentrations of 2 mM. The integrated cross section of103Rh/, /103mRh determined by this method was found to be 6.8±3.4 b MeV at 3.2 MeV.

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