[en] A detailed description of minerals of the Pribram uranium deposit is given. The introductory general part includes basic information on the deposit, its geological structure, petrographic structure, geological evolution and ways of its exploitation. The main, systematic part, deals in detail with all minerals that have hitherto been found in the area of the deposit. (P.A.). 1 fig., 12 photographs

[en] The angular distributions of transition radiation (TR) arising on the vacuum-metal boundary and directed towards metal have been calculated on the basis of TR general equations. Such properties of Vavilov-Cherenkov radiation in the absorbing medium as its directional property, polarization and radiation energy are considered in detail. Special attention is drawn to the considerable contribution of VaVilov-Cherenkov radiation to the intensity of the radiation, observed in experiments on optical TR. In particular, the coincidence of theoretical and experimental curves in the case of the systematic anticoincidence of TR levels is explained. A new explanation is given to the appearance of the perpendicular component. Different ''forward'' and ''backward'' background levels are explained

[en] After the successful basic solution of the Nb₃Ge and Nb₃Si problems, optimization strategies and quality criteria were developed for high Tc superconducting (HTCS) samples in analogy. After improvements of the sputtering system, the preparation parameters were tightly controlled, leading to samples with a reproducible linear slope of the specific resistance ρ(T). Further improvements by us and Poppe et al. lead to the preparation of 123 films with non-linear ρ(T) curves above 120K. A generalization to a T² behavior of ρ(T) leads to the further generalization that defect free HTCS are essentially two dimensional in nature, with all ensuing consequences. The momentum transport of the moving charge cariers requires, because of momentum conservation, a mechanism to transfer momentum to the lattice (momentum relaxation). The qualitative theory developed for two dimensional (2D) systems shows that the electron-phonon interaction is strongly suppressed and hence that the weaker electron-electron interaction dominates. That theory makes numerous predictions, which so far are confirmed by experiments. In particular, it accounts for the extreme temperature dependence of the mean free path and the Hall effect. It is inferred that the mechanism of HTCS is predominantly due to electron-electron interaction - probably of bipolaron nature, as indicated by experiment. At this point experiment meets just a few theories, that conform with the experimental facts and above theory, all based on the quasi-particle theory of electron-electron interaction. The theory of Newns, Pattnaik and Tsuei should have a T² shape of ρ(T) and, because E_F lies near a nearly logarithmic van Hove singularity, accounts for the high Tc. Ruvalds and Virosztek's theory predicts the T² shape of ρ(T). (orig./GSCH)

[en] A design of a cryostat, intended especially for radiation detectors is described. It essentially is a cooling device designed for automatic maintaining detector temperature in a very narrow low-temperature range. (V.V.)

[en] Predictions of OTR and VChR theories are analyzed and compared with the known experimental data obtained under the conditions when both radiations can influence each other. It is shown that the Tamm formula, describing the VChR emitted by a charged particle at the finite length of its trajectory, can be derived from OTR interference occurring at two boundaries. 14 refs.; 13 figs

[en] Demands are presented relating to the amount, purity and other parameters of waste waters discharged from the area of the Dukovany nuclear power plant. Existing experience with the power plant's water management is presented as are methods of alleviating existing shortcomings. Most identified shortcomings originate in the project. (M.D.)

[en] As proposed, by Ruzicka and Williams (1965) and demonstrated by Ruzicka and Lamm (1967a and b) and Briscoe et al (1967) automation of radiometric analyses presents a number of advantages viz conventional, manual methods: (a) the possibility of processing a large number of unattended determinations; (b) minimization of radioactive contamination; (c) the use of methods, which could not have been employed in manual handling (Ruzicka and Lamm 1967a); (d) self correction for decay.

[en] The classical formula for the intensity of the optical bremsstrahlung (OB) emitted by a charged particle moving in a transparent medium with a velocity above the Vavilov-Cherenkov radiation (VChR) threshold is analysed in the paper. The Cherenkov properties acquired by the OB at βn>1 are shown to be independent of the constant velocity of the particles. All OB properties (including its Cherenkov character) are explained using interference of prompt bremsstrahlungs that appear during acceleration of a particle and are introduced in formulation of the problem. 13 refs.; 7 figs

[en] Pure phase B1 NbN layers could be sputtered in our laboratory only with a maximum T_c of 15.9 K and a residual resistance ratio RRR of <0.9. Samples with a T_c of up to 16.7 K invariably had a large fraction of hexagonal foreign phase. If under similar conditions one sputters layers in the presence of small amounts of Al, one obtains pure B1 phase NbN layers with a maximum T_c of 16.9 K. The RRR rises to values of up to 1.16. The specific resistance drops from typical values of around 400 μΩcm to values as low as 73 μΩcm. The width of the X-ray lines drops occasionally, indicating increased grain size. Al acts like a catalyst, being substituted with less than 0.03 at% for a high T_c layer. When Al is substituted for Nb in detectable quantities both T_c and the lattice parameter drop. To verify the above results the experiment was repeated in a magnetron rather than a RF sputter system with similar outcome. (orig.)

No abstract available