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Showing papers by "Paul Scherrer Institute published in 1989"


Journal ArticleDOI
TL;DR: The textor liners and limiters of TEXTOR have been coated in situ with a boron containing carbon film using a RG discharge in a throughflow of 0.8 He + 0.1 B2H6 +0.1 CH4 as mentioned in this paper.

272 citations


Journal ArticleDOI
TL;DR: The structure of the 80 K superconductor YBa 2 Cu 4 O 8 has been measured as a function of temperature and pressure between 5 K and 165 K by high resolution neutron powder diffraction as mentioned in this paper.
Abstract: The structure of the 80 K superconductor YBa 2 Cu 4 O 8 has been measured as a function of temperature and pressure between 5 K and 165 K by high resolution neutron powder diffraction. The oxygen bridging CuO planes to double CuO chains moves away from the chains, toward the planes as T c increases with increasing pressure, indicating charge transfer to the planes. A similar effect occurs when YBa 2 Cu 3 O 6+ x is oxidised to YBa 2 Cu 3 O 7 , again increasing T c . The a - and c -axes of YBa 2 Cu 4 O 8 increase smoothly with temperature, but the b -axis, parallel to the direction of the CuO chains, appears to have a minimum near T c . This results in a slight inflexion in the orthorhombic distortion near T c , similar to that observed in YBa 2 Cu 4 O 7 . The oxygens within these chains appear disordered even at low temperature, again as in YBa 2 Cu 4 O 7 . However, in YBa 2 Cu 4 O 8 oxygens from the CuO-planes also have relatively large out-of-plane amplitudes. High resolution electron microscopy and diffraction show that YBa 2 Cu 4 O 8 , unlike YBa 2 Cu 3 O 7 , does not have planar structural defects; there are no twins or superstructures.

210 citations


Journal ArticleDOI
TL;DR: A simple model to incorporate inelastic energy losses into molecular-dynamics simulations of high-energy radiation damage, which at the same time describes the metallic thermal conductivity by coupling the ions to a thermal reservoir based on a local-density description of stopping power.
Abstract: We propose a simple model to incorporate inelastic energy losses into molecular-dynamics simulations of high-energy radiation damage, which at the same time describes the metallic thermal conductivity by coupling the ions to a thermal reservoir. Both expressions are based on a local-density description of stopping power. We provide an empirical expression to describe the strength of the ion-electron coupling, which is a function of the local electronic density. The model is then adequate to those simulations where the ion-ion interactions are obtained from many-body potentials based on density-functional formalism.

174 citations


Journal ArticleDOI
Bernardo Adeva1, O. Adriani2, M. Aguilar-Benitez, H. Akbari3  +451 moreInstitutions (25)
TL;DR: The first physics runs of the L3 detector at LEP were reported in this article, where the authors determined the mass m z 0 and the width Γ z 0 of the intermediate vector boson Z 0 to bem z 0 =91.132±0.057 GeV (not including the 46 MeV LEP machine energy uncertainty).

152 citations


Journal ArticleDOI
TL;DR: Muon spin rotation experiments performed on superconducting samples clearly show that internal magnetic fields coexist at low temperatures with superconductivity forx\ensuremath{\le}0.15$.
Abstract: Muon spin rotation experiments performed on superconducting ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Cu}{\mathrm{O}}_{4}$ samples clearly show that internal magnetic fields coexist at low temperatures ($Tl2$ K) with superconductivity for $x\ensuremath{\le}0.15$. The magnetic fields in the superconducting state are an order of magnitude smaller than the corresponding fields in undoped ${\mathrm{La}}_{2}$Cu${\mathrm{O}}_{4}$. The data are discussed in the context of a magnetic pairing mechanism in high-${T}_{c}$ superconductors.

127 citations


Journal ArticleDOI
TL;DR: The characterization of colloids from the Grimsel Test Site granitic groundwater has been carried out after concentrating the natural colloids by diaultrafiltration in situ and in the laboratory as discussed by the authors.

112 citations


Journal ArticleDOI
TL;DR: In this paper, the sorption-desorption of uranium (VI) on Grimsel granite of Switzerland was studied under oxidizing conditions with an initial uranium concentration range of between 9.7 · 10−7 and 4.5· 10−4M, using a batch technique.
Abstract: The sorption-desorption of uranium (VI) on Grimsel granite of Switzerland was studied under oxidizing conditions with an initial uranium concentration range of between 9.7·10−7 and 4.5·10−4M, using a batch technique. The sorption coefficients varied between 8.0 and 0.4 ml/g and sorption was not fully reversible. The data could be fitted to a Freundlich isotherm. By fitting the data with the Dubinin-Radushkevich equation, a mean energy of sorption of 10.7 kJ/mol was calculated, which corresponds to the energy of ion exchange reactions. The kinetic data could be interpreted by assuming diffusion into the crushed granite particles. The calculated pore diffusion coefficient was between 2.0·10−11–7.7·10−11 m2/s.

106 citations


Journal ArticleDOI
TL;DR: In this paper, the possibility of reexpressing the M W − M Z interdependence in a form which is valid to all orders in perturbation theory is proposed.

102 citations


Journal ArticleDOI
TL;DR: In this paper, a variety of possible chemisorption models have been investigated for the K/Si(001)2\ifmmode\times\else\texttimes\fi{}1 interface by use of the local density formalism and the discrete variational method to carry out self-consistent total energy calculations with Hedin and Lundqvist exchange correlation.
Abstract: A variety of possible chemisorption models has been investigated for the K/Si(001)2\ifmmode\times\else\texttimes\fi{}1 interface by use of the local-density formalism and the discrete variational method to carry out self-consistent total-energy calculations with Hedin and Lundqvist exchange correlation. Cluster models with up to 89 atoms are adopted to simulate various chemisorption sites. Electronic structures, charge distributions, and bonding characteristics are studied and discussed. The binding energy and relative stability are determined with a total-energy approach. It turns out that the most stable site predicted---the cave site--has been ignored previously in both theoretical calculations and experimental analyses. However, it is the site towards which dangling bonds of the two nearest surface Si atoms are directed and looks to be a reasonable feature for chemisorption. The resulting K-Si bond length (3.22 A\r{}) is in good agreement with the latest surface extended x-ray-absorption fine-structure experimental value. A charge of about 0.5e per K atom is transferred from the K atom to the surface, indicating that a mixed type of bonding occurs. Moreover, for monolayer adsorption, a potassium chain formed on the surface tends to undergo a small zigzag Peierls-like deformation to form a lower-energy state.

94 citations


Journal ArticleDOI
TL;DR: A new measure for the performance of hidden units as well as output units is proposed, called conditional class entropy, which not only allows existing networks to be judged but is also the basis of a new training algorithm with which an optimum number of neurons with optimum connecting weights can be found.

88 citations


Journal ArticleDOI
TL;DR: In this article, the leading term in the low temperature expansion of the absorption lattice was calculated and some consequences for the pion distributions generated in high energy collisions of heavy nuclei.

Journal ArticleDOI
TL;DR: Fusion reactions of 48 Ca projectiles with 180 Hf, 184 W, 197 Au, 208 Pb and 209 Bi targets were studied in this article, where the results of the heavier systems were discussed in terms of the extra push model.

Journal ArticleDOI
TL;DR: Human peripheral blood lymphocytes cultured in the presence of low concentrations of bleomycin became significantly less sensitive to the induction of chromosomal damage than those which did not receive the pre-treatment with BLM, and responded with lower frequencies of chromatid and isochromatid breaks.
Abstract: Human peripheral blood lymphocytes cultured in the presence of low concentrations of bleomycin (BLM), 0.01–0.1 μg/ml, for 48 h and then treated with a high concentration (1.5 μg/ml) of the same agent or with 1.5 Gy X-rays, became significantly less sensitive to the induction of chromocomal damage than those which did not receive the pre-treatment with BLM. They responded with lower frequencies of chromatid and isochromatid breaks. These results lend further support to the operation of an adaptive repair system in lymphocytes which offers resistance and cross-resistance to the induction of chromosomal damage by the same or similar DNA-damaging agents.

Journal ArticleDOI
TL;DR: In this article, the fission and alpha activities associated with its decay and the alpha decays of its daughter, 4.3-s 258Lr, were measured by measuring the time-correlated pairs of parent and daughter alpha particles provided a unique identification of the presence of 262Ha.
Abstract: Studies of the halide complexation of element 105 in aqueous solution were performed on 34-s 262Ha produced in the 249Bk(18-O,5n) reaction. The 262Ha was detected by measuring the fission and alpha activities associated with its decay and the alpha decays of its daughter, 4.3-s 258Lr. Time-correlated pairs of parent and daughter alpha particles provided a unique identification of the presence of 262Ha. About 1600 anion exchange separations of 262Ha from HCl and mixed HC1/HF solutions were performed on a one-minute time scale. Reversed-phase micro-chromatographic columns incorporating triisooctyl amine (TIOA) on an inert support were used in the computer-controlled liquid chromatography apparatus, ARCA II. 262Ha was shown to be adsorbed on the column from either 12 M HCl/0.02 M HF or 10 M HCl solutions like its homologs Nb and Ta, and like Pa. In elutions with 4 M HCl/0.02 M HF (Pa-Nb fraction), and with 6 M HNO3/O.OI5 M HF (Ta fraction), the 262Ha activity was found in the Pa-Nb fraction showing that the anionic halide complexes are different from those of Ta, and are more like those of Nb and Pa. In separate elutions with 10 M HCl/0.025 M HF (Pa fraction) and 6 M HN03/0.015 M HF (stripping of Nb) the 262Ha was found to be equally divided between the Pa and Nb fractions. The non-tantalum like halide complexation of Ha is indicative of the formation of oxohalide or hydroxohalide complexes, like [NbOCU]" and [PaOCl4] or [Pa(OH)2Cl4]", at least for intermediate HCl concentrations, in contrast to the pure halide complexes in Ta, like [TaCl6]-.

Journal ArticleDOI
TL;DR: In this article, the MTH-system was proposed for seasonal storage of electricity, which consists of two closed loops: in the outer loop hydrogen is produced by electrolysis of water and later burned to give water again, in the inner loop the hydrogen is combined with toluene to give methyl cyclohexane.

Journal ArticleDOI
TL;DR: Influence de la copolymerisation avec la p-phenylenediamine, which agit comme reticulant sur le comportement electrochimique et la morphologie

Journal ArticleDOI
TL;DR: The radiative pion decay π + →e + ν e e + e − has been measured and values for the weak form factors F V, F A and R have been obtained as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, the in-situ, plasma-induced chemical vapour deposition and materials properties of boron-carbon coatings have been optimized for their application as renewable coatings of the first wall in tokamak devices.

Journal ArticleDOI
B. Rupp1, E. Pörschke, P. Meuffels, Peter Fischer1, P. Allenspach1 
TL;DR: In this paper, structural properties of homogeneous orthorhombic and tetragonal ErBa{sub 2}Cu{sub 3}O{sub {ital x}} powder samples were investigated by elastic neutron scattering.
Abstract: Structural properties of homogeneous orthorhombic and tetragonal ErBa{sub 2}Cu{sub 3}O{sub {ital x}} powder samples (6.1{le}{ital x}{le}7.0), prepared by a careful absorption-desorption procedure, were investigated by elastic neutron scattering. With decreasing oxygen content the distance between Cu(2)-O(2,3) planes and Cu(1)-O(4)-Cu(1) chains increases and the oxygen 2{ital q}(0,0,{ital z}) apex atoms O(1) move closer to the Cu-O-Cu chains. The copper-oxygen (1) distances do not vary continuously in the {ital z} direction but seem to change more rapidly when {ital x}{lt}6.5. The change of these distances can be correlated to the suppression of superconductivity in orthorhombic ErBa{sub 2}Cu{sub 3}O{sub {ital x}}. A distinction between the large anisotropic vibrational amplitudes of the Cu(1)-O(4)-Cu(1) broken-chain oxygen atoms and a split-site model for O(4) is not possible on the basis of the present data.

Journal ArticleDOI
TL;DR: The results suggest that [123I]Ro16-0154 is of potential clinical use as a BZD receptor imaging agent.

Journal ArticleDOI
TL;DR: It is speculated that the observed gradual evolution of magnetism in CeAl/sub 3/ is driven by the temperature dependence of competing magnetic interactions rather than by a divergence in the single-ion susceptibility, similar to what was recently proposed for the heavy-electron compound U/sub 2/Zn/sub 17/.
Abstract: Zero-, transverse-, and longitudinal-field muon-spin-rotation (..mu../sup +/SR) spectroscopy was performed on polycrystalline CeAl/sub 3/. The onset of frustrated quasistatic magnetic correlations below about 2 K, becoming partly coherent below 0.7 K, was detected. The occurrence of different components in the ..mu../sup +/SR signal with relative strengths showing a pronounced temperature dependence leads to the conclusion that these correlations develop in a spatially inhomogeneous, frustrated way. No evidence for a macroscopic phase transition was obtained by specific heat measurements and neutron-diffraction experiments on our sample. This indicates that the coherence length of the correlations must be very short even below 0.7 K. The effective magnetic moment was estimated to be about 0.5..mu../sub /ital B// per cerium atom. It is speculated that the observed gradual evolution of magnetism in CeAl/sub 3/ is driven by the temperature dependence of competing magnetic interactions rather than by a divergence in the single-ion susceptibility, similar to what was recently proposed for the heavy-electron compound U/sub 2/Zn/sub 17/.

Journal ArticleDOI
TL;DR: In this paper, the authors show that a South American butterfly, an Australian banknote, a European moth and an international credit card all use sub-micron grating microstructures as sophisticated optical components to achieve unique visual effects.
Abstract: What do a South American butterfly, an Australian banknote, a European moth and an international credit card have in common? The answer is they all use sub-micron grating microstructures as sophisticated optical components to achieve unique visual effects which are difficult to realize with more conventional optics. There is, however, a basic difference between these diffractive optical elements – the visual effect of the credit card hologram or the banknote diffraction grating is viewed in the first diffraction order, whereas the butterfly and moth structures are so fine that there is no first order under normal viewing conditions and the optical behaviour is seen primarily in the zero order (figure 1).

Journal ArticleDOI
TL;DR: In this article, a single-crystal of Pr2CuO4 in the temperature range from 1.5 to 300 K was used for bulk-magnetisation measurements and neutron-scattering experiments.
Abstract: Bulk-magnetisation measurements and neutron-scattering experiments were performed both on a polycrystalline sample and on a single-crystal of Pr2CuO4 in the temperature range from 1.5 to 300 K. Pr2CuO4 crystallizes with theT′ (Nd2CuO4)-type structure. We observed antiferromagnetic ordering of the Cu moments belowT N =(190±2) K in a single crystal and belowT N =(250±10)K in powder material. The magnetic unit cell dimensions area m =2a o ,c m =c o ;the Cu moments are oriented in the basal plane with a magnetic saturation moment of μCu=(0.45±0.12)μ B . Pr3+ does not order magnetically above 1.5K due to its crystal-field induced singlet ground state as verified by inelastic neutron scattering.

Journal ArticleDOI
TL;DR: The antibody-immobilized assay appeared to be ideal for the classical ELISA technique, whereas the antigen-immorphized method seemed to be best suited for automated assay systems using antibody in excess.

Proceedings ArticleDOI
01 Nov 1989
TL;DR: A very robust algorithm for the recognition of simple objects is developed, based only on orientationl information as image feature, and local polar coordinates for the model of the object, and it becomes apparent that orientational information is indeed a powerful image primitive.
Abstract: Orientational information can replace the traditional edges as basic image features ("primitives") for object recognition. A comparison of five different orientation operators on 3 x 3 windows is carried out, and it is found that these operators have similar performance. A first attempt at object recognition searches for minimum root mean square deviation of orientation in a picture. This technique shows better object discrimination than the traditional normalized cross-correlation of grey-level images. Additionally the parameters of the Gaussian distribution of orientational correlation can be accurately predicted by a simple theoretical model. The orientational correlation technique shows difficulties in recognizing geometrically distorted and partially occluded objects. For this reason a very robust algorithm for the recognition of simple objects is developed, based only on orientationl information as image feature, and local polar coordinates for the model of the object. Practical examples taken under difficult, natural conditions illustrate the reliable performance of the proposed algorithm, and it becomes apparent that orientational information is indeed a powerful image primitive.

Journal ArticleDOI
TL;DR: The results suggest that the amide tracer structure can generally be used to improve the quality of estradiol antibodies suffering from bridge binding effects.

Journal ArticleDOI
TL;DR: Human blood lymphocytes, pre-treated with very low concentrations of bleomycin for 48 h and then exposed to a high dose of the same agent or X-rays, became significantly less sensitive to the induction of chromosome damage than those which did not receive the pre-treatment, indicating an induction of 'adaptive repair' process.
Abstract: Human blood lymphocytes, pre-treated with very low (adaptation) concentrations of bleomycin for 48 h and then exposed to a high (challenge) dose of the same agent or X-rays, became significantly less sensitive to the induction of chromosome damage than those which did not receive the pre-treatment, indicating an induction of 'adaptive repair' process. This repair process was negated when 3-amino-benzamide, an inhibitor of poly (ADP) polymerase, was added to the cultures immediately after the challenge treatment. The magnitude of negation in the adaptation response was greater in the case of lymphocytes challenged with X-rays as compared with those challenged with bleomycin.

Journal ArticleDOI
Crameri R1, H.H. Brunner, R. Buchli, C. Wernli, W. Burkart 
TL;DR: The distribution of indoor Rn concentrations in different geological areas in Switzerland was studied using passive alpha-track detectors and the geology of the different areas was found to be an important factor in determining the mean value Rn levels.
Abstract: The distribution of indoor Rn concentrations in different geological areas in Switzerland was studied using passive alpha-track detectors. Measurements involving a sample of 400 single-family homes were made in the cellar, on the ground floor and the first floor, respectively. On the basis of a pilot survey, the country was divided into four zones in which the Rn distribution in houses was analyzed separately. The indoor exposure to Rn and Rn decay products is quite variable from region to region. The geology of the different areas was found to be an important factor in determining the mean value Rn levels. In the basin north of the Alps, where the population centers are located, a median Rn gas level of 47 Bq m-3 for the living area was found. The arithmetic mean value of 60 Bq m-3 in this region leads to an annual effective dose equivalent of about 1.8 mSv. For the population living in alpine areas, an arithmetic mean value exceeding 200 Bq m-3 will lead to an annual effective dose equivalent in the range of 6 mSv. The estimated exposure to Rn and Rn decay products for the upper one-percentile of the homes in the most affected alpine region even exceeds the annual limit of 50 mSv effective dose equivalent for occupational exposure.

Journal ArticleDOI
TL;DR: The indoor 222Rn level depends mainly on the subsoil geology, the cellar floor permeability, the basement aeration, the air-tightness of the homes, and the aeration habits of the occupants.
Abstract: The indoor 222Rn level depends mainly on the subsoil geology, the cellar floor permeability, the cellar aeration, the air-tightness of the homes, and the aeration habits of the occupants. These five parameters and the 222Rn levels in the cellar and in the living room on the ground floor were compiled in 80 one- or two-family houses of the central Swiss Alps. The 222Rn levels were measured with passive alpha track detectors. Houses located on a granite, ortho-gneiss or verrucano subsoil have a cellar 222Rn level that is on the average 4.4 times higher than houses which are built on grey-schist or sediments. The cellar level is on the average 5.4 times higher if the cellar has partially a gravel or earth floor than if the whole cellar surface is covered with a concrete floor. Energy-efficient, highly air-tightened homes have a living room level that is on the average 1.8 times higher than normally insulated conventional homes. In the cellars and the living rooms of the 80 houses considered, arithmetic mean 222Rn levels of 724 Bq m-3 (20 pCi L-1) and 178 Bq m-3 (4.8 pCi L-1), respectively, were found. In the central Swiss Alps 222Rn and 222Rn decay products lead to an estimated mean exposure of 5.3 mSv effective dose equivalent per year.

Journal ArticleDOI
TL;DR: In this article, it was demonstrated experimentally that, based on this concept, new types of information storage and programmable switching devices are conceivable and can be realized, more or less, with the present state of the art.