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[en] A new preparation of a ²²Na positron source is described. The source is entirely of glass, shock-proff enough for usual purposes and easy to handle. These advantages are combined with high ²²Na diffusion yields and low source corrections. (orig.)

[en] The radionuclide ²²Na is a potential astronomical observable that is expected to be produced in classical novae in quantities that depend on the thermonuclear rate of the ²²Na(p,γ)²³Mg reaction. We have measured the strengths of low-energy ²²Na(p,γ)²³Mg resonances directly and absolutely using a radioactive ²²Na target. We find the strengths of resonances at E_p=213, 288, 454, and 610 keV to be higher than previous measurements by factors of 2.4-3.2, and we exclude important contributions to the rate from proposed resonances at E_p=198, 209, and 232 keV. The ²²Na abundances expected in the ejecta of classical novae are reduced by a factor of ≅2.

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[en] A simple method is described for determining the neutron absorption cross sections for radionuclides produced and consumed in a reactor-neutron flux. Data were obtained for ²²Na which, through application of Westcott's procedure, yielded the following: sigma₀ = 51.1 +- 3.1 Kbarns, s₀ = 2.3 +- 0.1, and Σ' = 100 +- 10 Kbarns

[en] Synoptical conditions of the origin of the cosmogenic ⁷Be and ²²Na extremal concentrations in the surface air of Vilnus were investigated. The increased ⁷Be concentrations resulted from high-altitude valley formation in the western direction from the sampling point for 60% of all the cases and 74% of thases were related to the wind velocities exceeding 30 m/s at a height of 300 mb. The analysis of synoptical conditions in the surface layer has shown that the concentration increase occurred most often in the rear of a cyclone or at the eastern circumference of an anticyclone (30 per cent of the cases) and in the central part of an anticyclone (21 per cent of the cases)

[en] In this study, a gamma-gamma coincidence spectrometry was developed and examined for environmental low-level cosmogenic ²²Na monitoring purposes. The spectrometry consists of two bismuth germanate scintillators (BGO) and XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The developed spectrometry was optimized according to the considerations of output count rate and gamma peak energy resolution. This spectrometry provides a more sensitive and effective way to quantify even trace amounts of ²²Na with critical detection limit of 9 mBq. A sophisticated computer simulation was also created with the goal of obtaining a better understanding of the experimental results and gamma-gamma coincidence efficiencies at different sample geometries. (author)

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[en] The kinetics of Na²² migration corroborate the distribution pattern of the non-radioactive element after root absorption: the sodium content of the leaf laminae is very low whereas a building-up is observed in the conductive tissues, particularly in the roots. After absorption, sodium seems to be rapidly translocated to all the organs, then moves downwards to accumulate in the roots; this phenomenon may be a way, for the plant, to fight sodium intoxication. The absorption of radiosodium is independent of the specific activity of the nutrient solution and appears to be related to its volumic activity. Thus, sodium is not taken up selectively by the roots of Sorghum; its translocation mechanism is therefore of the passive type