6,066 research outputs found

    Characterization of new hybrid pixel module concepts for the ATLAS Insertable B-Layer upgrade

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    The ATLAS Insertable B-Layer (IBL) collaboration plans to insert a fourth pixel layer inside the present Pixel Detector to recover from eventual failures in the current pixel system, especially the b-layer. Additionally the IBL will ensure excellent tracking, vertexing and b-tagging performance during the LHC phase I and add robustness in tracking with high luminosity pile-up. The expected peak luminosity for IBL is 2 to 3centerdot1034 cm-2s-1 and IBL is designed for an integrated luminosity of 700 fb-1. This corresponds to an expected fluence of 5centerdot1015 1 MeV neqcm-2 and a total ionizing dose of 250 MRad. In order to cope with these requirements, two new module concepts are under investigation, both based on a new front end IC, called FE-I4. This IC was designed as readout chip for future ATLAS Pixel Detectors and its first application will be the IBL. The planar pixel sensor (PPS) based module concept benefits from its well understood design, which is kept as similar as possible to the design of the current ATLAS Pixel Detector sensor. The second approach of the new three dimensional (3D) silicon sensor technology benefits from the shorter charge carrier drift distance to the electrodes, which completely penetrate the sensor bulk. Prototype modules of both sensor concepts have been build and tested in laboratory and test beam environment before and after irradiation. Both concepts show very high performance even after irradiation to 5centerdot1015 1 MeV neqcm-2 and meet the IBL specifications in terms of hit efficiency being larger than 97%. Lowest operational threshold studies have been effected and prove independent of the used sensor concept the excellent performance of FE-I4 based module concepts in terms of noise hit occupancy at low thresholds.Comment: Part of 9th International Conference on Position Sensitive Detectors (PSD9

    Modelling the Northeast Atlantic circulation : implications for the spring invasion of shelf regions by Calanus finmarchicus

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    The appearance in spring of the copepod Calanus finmarchicus in continental shelf waters of the northeastern Atlantic has been hypothesized to be mainly attributable to invasion from across the continental slope rather than in situ overwintering. This paper describes the application of a hydrodynamic circulation model and a particle-tracking model to Northeast Atlantic waters in order to assess the influence of the flow field and ascent migration parameters on the spring invasion of C. finmarchicus. For hydrodynamic modelling, the Hamburg Shelf-Ocean Model (HAMSOM) was applied to the North Atlantic and Nordic Seas and forced with daily mean atmospheric data. Simulated flow fields from HAMSOM serve as forcing functions for a particle-tracking model of the same region. The robustness of the simulated shelf invasion in three target boxes of the Northeast Atlantic Shelf was assessed by means of a sensitivity analysis with respect to variations in four key migration parameters: overwintering depth, ascent rate, ascent timing, and depth during residence in upper layers. The invasion of the northern North Sea and Norwegian Shelf waters is more sensitive to ascent migration parameters than invasion of the Faroese Shelf. The main reason for enhanced sensitivity of the North Sea invasion is the time and space-dependent flow structure in the Faroe-Shetland Channel. Dense aggregations of overwintering C. finmarchicus are found in the Channel, but because of the complex flow field only a proportion of the overwintering stock has the capacity to reach the North Sea

    Characterization of Thin Pixel Sensor Modules Interconnected with SLID Technology Irradiated to a Fluence of 21015\cdot 10^{15}\,neq_{\mathrm{eq}}/cm2^2

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    A new module concept for future ATLAS pixel detector upgrades is presented, where thin n-in-p silicon sensors are connected to the front-end chip exploiting the novel Solid Liquid Interdiffusion technique (SLID) and the signals are read out via Inter Chip Vias (ICV) etched through the front-end. This should serve as a proof of principle for future four-side buttable pixel assemblies for the ATLAS upgrades, without the cantilever presently needed in the chip for the wire bonding. The SLID interconnection, developed by the Fraunhofer EMFT, is a possible alternative to the standard bump-bonding. It is characterized by a very thin eutectic Cu-Sn alloy and allows for stacking of different layers of chips on top of the first one, without destroying the pre-existing bonds. This paves the way for vertical integration technologies. Results of the characterization of the first pixel modules interconnected through SLID as well as of one sample irradiated to 210152\cdot10^{15}\,\neqcm{} are discussed. Additionally, the etching of ICV into the front-end wafers was started. ICVs will be used to route the signals vertically through the front-end chip, to newly created pads on the backside. In the EMFT approach the chip wafer is thinned to (50--60)\,μ\mum.Comment: Proceedings to PSD

    Ultraschall und Arthritis

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    Zusammenfassung: Die Arthrosonographie ist ein etabliertes und validiertes diagnostisches Verfahren in der Rheumatologie. Durch ihren hohen Weichteilkontrast ist die Sonographie in der Lage, Weichteilveränderungen wie z.B. Synovialisveränderungen zu detektieren. Knorpel- oder Knochenveränderungen im Rahmen einer rheumatoiden Arthritis (RA), einer Spondyloarthritis oder einer Kristallarthritis können teilweise nur sonographisch oder in vielen Fällen zu einem früheren Zeitpunkt als mit der konventionellen Bildgebung erfasst werden. Die Aktivität entzündlicher Veränderungen kann mit Hilfe der Doppler- und Power-Dopplersonographie gut dargestellt werden. In der Früharthritisdiagnostik gewinnt die Sonographie zunehmend an Bedeutung, insbesondere bei undifferenzierter Arthritis und bei unauffälligem Röntgenbefund. Neben der Diagnostik der Früharthritis und dem Therapiemonitoring einer RA erlaubt die Sonographie die Darstellung pathognomonischer Veränderungen bei seronegativen Spondyloarthritiden und Kristallablagerungserkrankungen wie Gicht, Chondrokalzinose und Apatitose. Sonographiegesteuerte diagnostische und therapeutische Interventionen zeichnen sich durch eine extrem hohe Treffsicherheit und Verbesserung der klinischen Wirksamkeit verglichen mit ungesteuerten Verfahren aus. Zusammenfassend nimmt die Sonographie zunehmend einen zentralen Stellenwert ein in der Abklärung und Behandlungssteuerung bei entzündlichen Gelenkerkrankunge

    Elaboration and TEM structural study of interfaces in composites produced by precipitation

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    Model ceramic matrix composites have been manufactured in a wide range of materials using the precipitation of a metal (Cu, Ni, Cr) in a ceramic matrix (nitride AIN or oxides MgO, Al2O3) providing, in each case low energy configurations at the heterophase interfaces. In connection to microelectronic applications, copper metallic particles precipitate in AIN after implantation by copper ions and anneal of the ceramic matrix. Faceted particles are imaged by HRTEM and are associated to a low energy structural and chemical configuration. Internal reduction experiments have been carried out on (Mg,Ni)O, (Mg,Cu)O and (Al,Cr)2O3 mixed oxides; the morphology, chemical composition and orientation relationship of the different precipitates are obtained through TEM observations and discussed in terms of interfacial energy and precipitate growth mechanism and kinetics. Conventional and high resolution TEM in conjonction to structural models have allowed a comprehensive description of the interface

    Photoassociation of cold atoms with chirped laser pulses: time-dependent calculations and analysis of the adiabatic transfer within a two-state model

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    This theoretical paper presents numerical calculations for photoassociation of ultracold cesium atoms with a chirped laser pulse and detailed analysis of the results. In contrast with earlier work, the initial state is represented by a stationary continuum wavefunction. In the chosen example, it is shown that an important population transfer is achieved to 15\approx 15 vibrational levels in the vicinity of the v=98 bound level in the external well of the 0g(6s+6p3/2)0_g^-(6s+6p_{3/2}) potential. Such levels lie in the energy range swept by the instantaneous frequency of the pulse, thus defining a ``photoassociation window''. Levels outside this window may be significantly excited during the pulse, but no population remains there after the pulse. Finally, the population transfer to the last vibrational levels of the ground a3Σu+a^3\Sigma_u^+(6s + 6s) is significant, making stable molecules. The results are interpreted in the framework of a two state model as an adiabatic inversion mechanism, efficient only within the photoassociation window. The large value found for the photoassociation rate suggests promising applications. The present chirp has been designed in view of creating a vibrational wavepacket in the excited state which is focussing at the barrier of the double well potential.Comment: 49 pages, 9 figures, submitted to Phys. Rev.

    Stationary Josephson effect in a weak-link between nonunitary triplet superconductors

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    A stationary Josephson effect in a weak-link between misorientated nonunitary triplet superconductors is investigated theoretically. The non-self-consistent quasiclassical Eilenberger equation for this system has been solved analytically. As an application of this analytical calculation, the current-phase diagrams are plotted for the junction between two nonunitary bipolar ff-wave superconducting banks. A spontaneous current parallel to the interface between superconductors has been observed. Also, the effect of misorientation between crystals on the Josephson and spontaneous currents is studied. Such experimental investigations of the current-phase diagrams can be used to test the pairing symmetry in the above-mentioned superconductors.Comment: 6 pages and 6 figure

    Psychologische Prädiktoren für das Auftreten einer Major Depression und einer PTBS nach schweren Unfällen

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    Theoretischer Hintergrund/Fragestellung: Ziel unserer prospektiven Studie war die Identifikation von Prädiktoren für das Auftreten einer Depression im ersten halben Jahr nach einem Unfall. Methode: Es wurden 52 Unfallpatienten untersucht. Die Ersterhebung erfolgte innerhalb der ersten sechs Wochen nach dem Unfall. Ergebnisse: Depressive Patienten gaben kurz nach dem Unfall eine geringere Lebenszufriedenheit und soziale Unterstützung an und berichteten häufiger über psychische Störungen und traumatische Erlebnisse vor dem Unfall als Nicht-Depressive. Außerdem litten sie zum Zeitpunkt der Ersterhebung häufiger unter psychischen Störungen und fühlten sich durch die psychischen Symptome stärker beeinträchtigt. Schlussfolgerung: Die Ergebnisse legen nahe, dass Patienten mit einem Risiko für die Entwicklung einer Depression bereits kurz nach einem Unfall identifiziert werden können