[en] After the luminosity upgrade of the electron proton collider HERA, the proton bunch length will become relevant for the achievable luminosity. New, strong focussing, superconducting magnets inside the detectors H1 and ZEUS lead to smaller cross sections at the interaction regions and with that, to higher luminosity. Due to the strong focussing, the beta function and the bunch length have a comparable magnitude. This enhances the effective cross section, 'hour-glass-effect' [1]. A reduction of the bunch length would result in smaller effective cross sections and so further increase the luminosity. Even at HERA energies of 920 GeV, protons do not lose a significant amount of energy, due to synchrotron radiation, because of their large rest mass. Hence, there is no natural damping of unwanted beam oscillations, as is the case for electrons or positrons. Coherent oscillations of the proton beam lead to an increase of the beam dimensions. Shorter bunch lengths at high energy are achievable by suppressing the coherent oscillations at injection and during acceleration. For an investigation of the origin of coherent oscillations, powerful longitudinal diagnostic tools are indispensable. Therefore, a fast longitudinal diagnostic system was developed, which permits real time measurements of bunch phase and length for all 180 bunches during one turn. Beam loading transients and the accelerating voltages can be examined with a fast cavity field diagnostic. The vacuum system of the HERA proton ring was carefully designed to keep the impedance, which could drive beam oscillations, as low as possible. Therefore, measures are needed to suppress the oscillations. The fast longitudinal diagnostic system provides the signals, needed for a RF feedforward and a coupled-bunch feedback. The new diagnostic system permits novel observations and experiments at HERA. One can observe coupled-bunch oscillations during acceleration, which are correlated with an increase in the longitudinal emittance. The impact of bunch oscillations on the beam loading transients can be demonstrated. Measurements of the longitudinal beam transfer function and measurements of decoherence times, together with beam echoes, yields important beam dynamical parameters. Since a further reduction of the all over impedance is not easily achievable, the suppression of coupled-bunch oscillations must be done by active systems. The results obtained in this thesis, provide the necessary information for the design of a coupled-bunch feedback system, whose task is the preservation of the longitudinal emittance. (orig.)

[en] During the experimental series MOL 16 the interaction between fuel and cladding of the type 1.4988 has been investigated. Varied parameters were the cladding temperature, burnup and stoichiometry of the fuel and the influence and positioning of stabilisators. In total 14 pins were used in 5 measuring campaigns, while in the experiment 16-5 two pins of 180 mm length, both with O/M=1.99 and 87 % theoretical density and a target temperature at clad inner wall of 560±30 deg C were investigated. This report describes the three years operational period of the 16-5 experiment in BR-2

[en] Results of five series of high-precision viscosity measurements on gaseous propane, each differing in density, are reported. The measurements were performed in a quartz oscillating-disk viscometer with small gaps from room temperature up to about 625 K and for densities between 0.01 and 0.05 mol · L^-1. The experimental data were evaluated with a first-order expansion, in terms of density, for the viscosity. Reduced values of the second viscosity virial coefficients deduced from the zero-density and initial-density viscosity coefficients for propane and for further n-alkanes are in close agreement with the theoretical representation of the Rainwater-Friend theory for the potential parameter ratios by Bich and Vogel. A new representation of the viscosity of propane in the limit of zero density is provided using the new experimental data and some data sets from literature. The universal correlation based on the extended principle of corresponding states extends over the temperature range 293 to 625 K with an uncertainty of ±0.5% and deviates from earlier representations by about 1% at the upper temperature limit

[en] Two new HFD-B(He)Ros potentials have been presented. The calculated results are very close to those computed with the HFD-Be(He) potential proposed in the literature. The most reliable second virial coefficients, viscosities and thermal conductivities are practically described within their experimental uncertainties. (author)

[en] Experimental viscosity data of ethane, carbon dioxide, and three mole fractions of the binary system carbon dioxide + ethane in the temperature range 293.15≤T≤633.15 K and in the density range 0.01≤p≤0.05 mol · L^-1 reported earlier were evaluated simultaneously to find out a useful correlation and extrapolation scheme for the viscosity of binary systems in the range of moderate densities. A procedure based on the ideas of the modified Enskog theory has been found to give the best results. Dependent on temperature, the collision diameters related to the equilibrium radial distribution function at contact are fitted to viscosity values of the pure substances and of at least one mixture. The results are compared with experimental data from the literature. A recommendation is given concerning the density range in which the first density contribution to the viscosity coefficient of the system carbon dioxide + ethane is sufficient to be included

[en] The quantitative analysis of SO₃, CaO, and SiO₂ in products of the cement industry by X-ray fluorescence spectrometry is influenced by inhomogeneities of the samples. After correction the calibration curve by comparison with results obtained from analysis of a parallel sample in dissoloed state or melt-down test the interfering effects can be eliminated

[en] X-ray fluorescence analysis (XRFA) has been introduced into quality and process control of the cement production process. Devices needed for sampling are described and the control mechanism assisted by a process computer are briefly explained. The samples are pressed into tablets and analysed. XRFA pulse rates of the elements to be determined are evaluated by means of linear calibration curves

[en] A model for the relaxation time of impurity electron phonon interaction is presented, based on the assumption that, for excited phonon emission, a temperature dependent Lorentzian function properly represents the phonon energy distribution. Preliminary results obtained for the calculated thermal conductivity of MgO/Fe²⁺ and ZnS/Fe²⁺ well agree with experimental results

[en] The experiments reported in this paper were designed to answer some questions relating to the augmenting effect of storage of sperm in the inseminated female, on the frequency of translocations in spermatozoa treated with the trifunctional alkylating agent trenimon. To see whether, upon storage, more chromosome breaks become available for interaction, sperm cells that had been treated with trenimon in the male were exposed to X-irradiation before or after 6 days storage in the female. The data of the first-experiment indicated that in unstored sperm the translocation yield after treatment with both trenimon and X-rays, was lower than that expected on the basis of additivity of yields of the single treatments. The negative synergism between trenimon and X-irradiation has been confirmed in further experiments with both translocations and dominant lethals. The latter finding does not support an interpretation in terms of selective elimination of translocations by cell death. Following storage, the translocation frequencies increase and after combination of trenimon and X-rays, yields corresponding to additivy of frequencies with single treatments are observed. To study whether changes in the material repair system contribute to the storage effect, trenimon-treated males were mated with aged females and the frequencies of translocations were determined. It was found that these frequencies were similar to those in young (unstored) females; this result suggests that the possibility raised above is unlikely. (Auth.)

[en] Magnetic resonance imaging is used routinely with much success for various problems in different medical disciplines. However, the patient is exposed to static as well as to time-dependent magnetic fields and radio-frequency electromagnetic fields. In 1997 the Strahlenschutzkommission, the German Radiological Protection Commission, passed a recommendation on the use of magnetic resonance in medical diagnostics. In this recommendation basic values related to thresholds for physiological effects and limits for restricted and unrestricted use are given. In the following the aim and applicability of this recommendation are discussed, as well as the thresholds and different limits for the static magnetic fields, the gradient fields and the radio-frequency fields. Additionally, advice is given for the protection of high-risk patients, personnel, and the general public, together with further safety advice as well as recommendations for users and manufacturers. (orig.)