[en] The invention concerns a method for the determination of the radiation activity of contaminated constructional components by means of detectors. The measured values are processed and displayed by a computer. From the given parameters the current and error-oriented threshold contamination or threshold impulse rate is determined continuously with the expiration of the gate time and is then compared with the actual measured value of the specific surface activity or mass-specific activity or impulse rate. (orig.)

[en] The concept of handling the disassembly of active system components planned the application of mechanical separation methods. Thermal separation methods came into question only in exceptional cases. In general, the required shielding was realized by appropriate filling of the container or by additional shielding with plates of rolled or cast lead obtained during disassembly. The heat exchangers shielded by cast steel casings with flanged closures could only be put into the containers after being disassembled. The shielding required for the transport and storage of the RPV with shield tank was performed by using material available on board. The decontamination measures and the release procedure were rendered difficult due to the layout of a great part of the large shieldings in the region of the service room and waste water tank shieldings. (DG)

[en] Some aspects of the coupling between phonons and electrons and the interaction between electrons at metal surfaces are reviewed. Surface science techniques as diverse as electron energy loss spectroscopy, angle-resolved photoelectron spectroscopy, and scanning tunnelling microscopy are employed to study these interactions. Electron-phonon and electron-electron coupling are discussed in terms of renormalized phonon dispersion relations, and increased decay rates of electronic excitations. (orig.)

[en] Experiments dealing with electron-phonon coupling at metal surfaces are reviewed. Issues as diverse as reconstructions at surfaces, Kohn anomalies, Peierls distortions, electron transfer between adsorbate and substrate and superconductivity are addressed. We discuss the renormalization of surface phonon and electron dispersion due to electron-phonon coupling as well as the impact of the electron-phonon interaction on the lifetime of electronic excitations. It is emphasized that in many cases only the combination of analyses of vibrational and electronic structure leads to an unambiguous and comprehensive description of the surface dynamics

[en] We have investigated both the substrate phonons and adsorbate vibrations of the clean and hydrogen-covered Mo(110) surface by high-resolution electron-energy-loss spectroscopy. With increasing hydrogen coverage the specular spectra together with elastic intensity measurements at bar S and bar N lead us to the conclusion that, in analogy to the W(110) surface, there exist three ordered phases at 110 K: three domains of a ''(2x1)'' at about 0.5 ML, a (2x2) at about 0.75 ML, and a (1x1) phase at full monolayer coverage. Starting from the elastic beam and extending up to the parallel hydrogen and deuterium vibration an enhanced background is observed for all phases in the specular spectra. The background increases monotonically with coverage. This background is probably partly due to an electron-hole damping mechanism and partly due to an enhanced mobility of the hydrogen adatoms. Additionally we present the dispersion of substrate phonons along the symmetry directions of the surface Brillouin zone. Our results confirm the helium atom scattering data and show that not only the Rayleigh wave but also the longitudinal mode exhibit a lowering of the frequency at a wave vector along bar Γ bar H and at the bar S point. Moreover, we have discovered a shallow dip in the dispersion curve already for the (2x2) phase. copyright 1997 The American Physical Society

[en] Three aspects of electron-phonon coupling at metal surfaces are reviewed. One aspect is the Kohn effect, which describes an anomalous dispersion relation of surface phonons due to quasi-one-dimensional nesting of Fermi surface contours. The combination of electron energy loss spectroscopy and angle-resolved photoelectron spectroscopy allows us to unambiguously characterize Kohn anomaly systems. A second aspect is the nonadiabatic damping of adsorbate vibrations. Characteristic spectroscopic line shapes of vibrational modes allow us to estimate the amount of energy transfer between the vibrational mode and electron-hole pairs. Case studies of a Kohn anomaly and nonadiabatic damping are provided by the hydrogen- and deuterium-covered Mo(110) surface. As a third aspect of interaction between electrons and phonons, local heating of a C₆₀ molecule adsorbed on Cu(100) and in contact with the tip of a scanning tunnelling microscope is covered

[en] Information in relation to the measurement devices for very low radioactivity, applied in the decommissioning of electronuclear power plants, is scarce and scattered. However, some realistic information can be obtained from the specialists working on nuclear plant dismantling sites. In practice, the in situ measurements deal with two or three radionuclides only. The other containments must be determined on some samples in laboratories by means of radioanalysis and spectrometry technologies. These technologies are briefly described. One of the problems concerns the detection threshold of the measuring instruments. This threshold varies in relation with the detector efficiency, the background and the measurement duration. The application of this concept of threshold to various types of instrument is studied. Tables and graphs are given that sum up the various possibilities of detection for the usual detectors according to their effective area. The possibility of reducing the number of monitoring points using statistical methods is presented

[en] Using scanning tunneling microscopy at low temperatures we investigated cesium adsorbed on Cu(111). At low coverages we observe a hexagonally ordered Cs adsorption layer with a mutual adsorbate distance of 1.1 nm. This distance is discussed in terms of a commensurate adsorption superstructure which is stabilized by long-range adsorbate interactions mediated by Cu(111) surface state electrons. Intermediate coverages are characterized by incommensurate superstructures which are rotated with respect to the substrate lattice. The rotation angle varies with coverage and follows a trend which is consistent with models of epitaxial rotation. With increasing coverage the adsorption layers are found to rotate toward alignment with the substrate

[en] The number of patients with immunosuppression is rising worldwide. The spectrum of diseases and pathogens in these patients differs widely from that of immunocompetent patients due to frequent opportunistic infections. Symptoms are sometimes unspecific, and imaging plays a key role in the management of these patients. The lungs are a frequent site of infection in immunosuppressed patients. Chest X‑ray is the starting point for radiological diagnostics, but shows only limited sensitivity and specificity for infections with atypical pathogens. Thus, computed tomography (CT) is of great importance and allows a better distinction between viral, bacterial, or fungal infections, as well as other noninfectious diseases. Even with CT, however, is exact specification of the pathogen unfortunately not possible. CT is also the main diagnostic tool for assessment of the abdomen, particularly in patients presenting with acute abdomen or when sonographic findings are inconclusive. Moreover, CT allows diagnostic and therapeutic interventions such as percutaneous biopsies, or abscess and fluid drainage.

[en] The conductance of single atoms and molecules is investigated with a low-temperature scanning tunnelling microscope. In a controlled and reproducible way, clean Ag(111) surfaces, individual silver atoms on Ag(111) as well as individual C₆₀ molecules adsorbed on Cu(100) are contacted with the tip of the microscope. Upon contact the conductance changes discontinuously in the case of the tip-surface junction while the tip-atom and tip-molecule junctions exhibit a continuous transition from the tunnelling to the contact regime