[en] In high-temperature reactors of the non-integrated type there is the possibility of failure for those pressure-sustaining components, which lie outside of the unburstable prestressed concrete pressure vessel. The severest imaginable depressurization accident is the double-ended break of one gas duct, which connects the reactor with the steam generator. As a consequence of this failure there will develop pressure differences acting on structural components of the primary circuit. These pressure differences are calculated with a multi-node computer model. The mechanical behaviour of the endangered components is estimated and improvements of the construction are proposed. (orig.)

[en] Using data collected with the ARGUS detector at the e⁺e^- storage ring DORIS II at DESY, particle-antiparticle oscillations in the B_d⁰ system have been studied. Besides the standard method of tagging the b-flavor with fast leptons, a new technique has been introduced based on identifying the B-meson quark content with charged D^*-mesons, thereby also separating neutral and charged B-decays. Combining the different methods applied, the strength of B⁰anti B⁰ oscillations, expressed in terms of the mixing parameter r, was found to be (19.1 ± 5.1 ± 4.4)%. Exploiting unitarity of the CKM matrix, this value leads to a lower limit on the top quark mass of m_t > or approx. 55 GeV/c². Using the upper bound on m_t from neutral current data (m_t < 190 GeV/c²) this analysis also constraints the CKM element vertical strokeV_tdvertical stroke to be larger than vertical strokeV_tdvertical stroke > 0.006. Furthermore this measurement predicts the strength of the yet unobserved B_s⁰ ↔ anti B_s⁰ transitions to lie in the range r_s > or approx. 0.8. (orig.)

[en] The subject fields, i.e. forest ecosystem research, forest damage research, open landscapes as ecosystems, are selected in accordance with the main fields of research of Goettingen university. A model forest is described in its various aspects. The population dynamics of forest vegetation is discussed in its diverse biotic and abiotic factors. Seasonal and site factors, soil and food chain contamination are gone into. (VT)

No abstract available

[en] The effect of acid rain and heavy metals on the biotic interactions in the soil of beech forest with mull, must, and limed must was investigated with the aid of close-to-nature microcosmos systems. Parameters made use of were the decomposition of carbon-14-labelled litter components and the turnover of the microflora in C, N, and P. As the results show, increased proton uptake will bear on rearly every stage of the decomposition process in mull soils. As a result, there may be litter accumulation on the ground and first signs of humus disintegration in the mineral soil of mull soils. A direct relation between the acidity of the environment and the extent of decomposition inhibition does not exist. Despite wide-ranging impairment of edaphic animals, the activity of the ground fauna still is to be considered as the most important buffer system of soils rich in bases. Acidic condition of the beech forest soils with the humus form 'must' led to drastic inhibition of litter decomposition, to a change of the effect of edaphic animals, and to an increase in N mineralization. The grazing animals frequently aggravate the decomposition inhibition resulting from acid precipitation. The comparision of the decomposition process in a soil containing must as compared to one containing mull showed acidic soils to be on a lower biological buffer level than soils rich in bases. The main buffer capacity of acidic soils lies in the microflora, which is adapted to sudden increases in acidity and which recovers quickly. In the opinion of the authors, simple liming is not enough to increase the long-term biogenic stability of a forest ecosystem. A stabilizing effect of the fauna, for instance on nitrogen storage, is possible only if forest care measuries are carried out, for instance careful loosening of the mineral soil, which will attract earthworm species penetrating deeply into the soil. (orig./MG) With 12 refs., 6 figs

[en] The reactor is of the two-loop Type. On the cold gas inlet of the core as well as on the hot gas outlet of the core, gas collecting rooms are planned. Each gas collecting room is divided by partition walls in such a way that each hot gas or cold gas pipe leads into a separate gas store. The partition walls have pressure compensating openings with a higher drag than that of the gas pipes. The gas pipes consist of coaxial pipes, and the hot gas pipe is fixed in the cold gas pipe. In case of a gas pipe fraction, the expansion wave leads into the gas stores and is held up by the partition walls without having an influence on the other cooling circuit. (DG)

[en] In the multi-loop type nuclear power plant the branching or concentration point of the parallel coolant gas loops is put closer to the reactor core region through which the entire coolant gas flows. For this purpose at least one of the gas plenums is subdivided by means of partition walls in such manner that the gas inlets and outlets of each coolant gas circuit open into a special gas chamber. It has got pressure relief openings with a flow resistance. In the accident case of failure of pressure retaining walls or gas ducts in one of the coolant gas circuits consecutive damages are avoided and the residual heat removal system is kept functioning. A bypass flow of the coolant cannot occur. (DG)

[en] The new radiometric method for determination of effective focal spots of X-ray tubes has been worked out. The method consists in sharp collimation of central beam of X-ray tube and measurement the focus dimensions like after line by means of scintillation detector. The results after digitalization are processed in computer and focal spot are determined in all directions. 6 refs, 12 figs

[en] The symmetry group of staggered lattice fermions is discussed as a discrete subgroup of the symmetry group of the Dirac-Kaehler equation. For the representation theory of this group, G. Mackey's generalization of E.P. Wigner's procedure for the construction of unitary representations of groups with normal subgroups is used. A complete classification of these irreducible representations by ''momentum stars'', ''flavour orbits'' and ''reduced spins'' is given. (orig.)

[en] Using the ARGUS detector at the e⁺e^- storage ring DORIS II at DESY an update of the B⁰-anti B⁰ mixing measurement has been performed including the new 1988 data. With a total of ∫ Ldt = 172 pb^-1 on the Υ(4S) resonance and 55 pb^-1 in the nearby continuum the dilepton analysis yields a mixing parameter of r = 0.22 ± 0.07 ± 0.06. The authors have also investigated charge correlations between a D*⁺ and one or two leptons. Combining the results of all three methods they obtain r = 0.22 ± 0.07. 7 refs., 2 figs., 3 tabs