1,772 research outputs found

    Synthesis and Structure of Ba7F12Cl2

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    Calcium-free Solid Solutions in the System Ba7F12Cl2−xBrx (x<1.5), a Single-component White Phosphor Host

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    We have recently prepared solid solutions of Ba∼6.3Ca∼0.7F12Cl2−xBrx with x ranging from 0 to 2. In this work, the synthesis and single crystal X-ray structure of calcium-free crystals of Ba∼6.9Na∼0.2F12Br0.6Cl1.4 (space group P63/m, a=10.6024(10), c=4.2034(4)Å), Ba∼6.9Na∼0.2F12Br1.4 Cl0.6 (space group P63/m, a=10.6155(9), c=4.2355(4)Å) and Ba∼6.9Na∼0.2Br1.32Cl0.68F12 (space group P63/m, a=10.6218(9), c=4.2284(4)Å) are reported. These crystals systematically present additional electron density at the 0 0 0.25 position which is associated with the presence of small, but significant amounts of Na+ ions in the crysta

    Simulation of semiconductor detectors in 3D with SolidStateDetectors.jl

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    The open-source software package SolidStateDetectors.jl to calculate the fields and simulate the drifts of charge carriers in solid state detectors, together with the corresponding pulses, is introduced. The package can perform all calculations in full 3D while it can also make use of detector symmetries. The effect of the surroundings of a detector can also be studied. The package is programmed in the user friendly and performance oriented language Julia, such that 3D field calculations and drift simulations can be executed efficiently and in parallel. While all kinds of semiconductor devices can be simulated, special emphasis is put on germanium detectors. The verification of the package is shown for an n-type segmented point-contact germanium detector. Additional features of SolidStateDetectors.jl planned for the near future are listed.Comment: 21 pages, 9 figure

    Lifetime measurements of Triaxial Strongly Deformed bands in 163^{163}Tm

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    With the Doppler Shift Attenuation Method, quadrupole transition moments, QtQ_t, were determined for the two recently proposed Triaxial Strongly Deformed (TSD) bands in 163^{163}Tm. The measured QtQ_t moments indicate that the deformation of these bands is larger than that of the yrast, signature partners. However, the measured values are smaller than those predicted by theory. This observation appears to be valid for TSD bands in several nuclei of the regionComment: 8 pages, 5 figures. Submitted to Physical Review

    Improving Co-benefits and 'Triple Win' Impacts from Climate Action: The Role of Guidance Tools

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    This CDI Practice Paper by L.O. Naess, M. Hagemann, B. Harvey, F. Urban, S. Hendel-Blackford and N. Höhne addresses the role of tools in supporting interventions to achieve the ‘triple wins’ of adaptation, mitigation and development. Over recent years there has been a proliferation of guidance tools to support adaptation or mitigation, increasingly in a development context, but little work on the role tools play in helping to bridge the gap between these three areas in practice. Based on a review of tools in view of ‘climate compatible development’, the paper suggests key considerations for how tools could help achieve ‘triple wins’. They include (1) the importance of understanding how tools are a way of defining and shaping a goal, not merely helping to implement actions to achieve it; (2) the value of acknowledging different starting points, and that a lot of the integration is happening – and will continue to happen – on the side of users; and (3) because tools cannot provide all the answers to complex problems they need to be complemented by analysis of actors, goals and outcomes.UK Department for International Developmen

    Solving inverse electromagnetic scattering problems via domain derivatives

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    We employ domain derivatives to solve inverse electromagnetic scattering problems for perfect conducting or for penetrable obstacles. Using a variational approach, the derivative of the scattered field with respect to boundary variations is characterized as the solution of a boundary value problem of the same type as the original scattering problem. The inverse scattering problem of reconstructing the scatterer from far field measurements for a single incident field can thus be solved via a regularized iterative Newton scheme. Both the original forward problem and the problem characterizing the domain derivative are formulated as boundary integral equations and we carefully describe how these formulations are obtained in the case of Lipschitz domains. The integral equations are solved using the boundary element library Bempp. A number of numerical examples of shape reconstructions are presented

    Seamless integration of the coastal ocean in global marine carbon cycle modeling

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    We present the first global ocean-biogeochemistry model that uses a telescoping high resolution for an improved representation of coastal carbon dynamics: ICON-Coast. Based on the unstructured triangular grid topology of the model, we globally apply a grid refinement in the land-ocean transition zone to better resolve the complex circulation of shallow shelves and marginal seas as well as ocean-shelf exchange. Moreover, we incorporate tidal currents including bottom drag effects, and extend the parameterizations of the model's biogeochemistry component to account explicitly for key shelf-specific carbon transformation processes. These comprise sediment resuspension, temperature-dependent remineralization in the water column and sediment, riverine matter fluxes from land including terrestrial organic carbon, and variable sinking speed of aggregated particulate matter. The combination of regional grid refinement and enhanced process representation enables for the first time a seamless incorporation of the global coastal ocean in model-based Earth system research. In particular, ICON-Coast encompasses all coastal areas around the globe within a single, consistent ocean-biogeochemistry model, thus naturally accounting for two-way coupling of ocean-shelf feedback mechanisms at the global scale. The high quality of the model results as well as the efficiency in computational cost and storage requirements proves this strategy a pioneering approach for global high-resolution modeling. We conclude that ICON-Coast represents a new tool to deepen our mechanistic understanding of the role of the land-ocean transition zone in the global carbon cycle, and to narrow related uncertainties in global future projections

    Synthesis and Structure of Ba

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    Abstract. Crystals of ordered and disordered Ba 7 F 12 Cl 2 were prepared by flux growth and solid state reactions. These new structures were characterized by single crystal and powder X-ray diffraction. The disordered variant which shows disorder on one of the cation sites was obtained from a BaF 2 + BaCl 2 + NaCl/NaF flux. It has hexagonal space group P6 3 /m (176) with one formula unit per unit cell. The lattice constants are a = b = 1059.55(5) pm and c = 420.10(4) pm (at 21°C). The structure was refined to R(R w ) = 0.026(0.030) for 346 independent reflections and 26 parameters. Slow cooling of a mixture of BaF 2 and LiCl yields the ordered variant. This one crystallizes in the hexagonal space group P6 (174) with one formula per unit cell. Lattice constants at 21°C are a = b = 1063.46(2) pm and c = 417.52(1) pm. The structure was refined to R(R w ) = 0.017 (0.017) for 638 independent reflections and 45 parameters. The structural arrangement and the interatomic distances of the two variants are mutually similar. The barium atoms have coordination number nine. Propeller-type arrangements with a chloride ion on the axis and the fluoride ions as blades are observed. These latter ones are interconnected into`channels&apos; of tricapped fluoride prisms. Occupation disorder of the barium sites in the channels of the disordered variant makes the main difference between the two. An unexpectedly high X-ray density obtained for both variants of Ba 7 F 12 Cl 2 can be correlated to the density of other barium fluorohalides having a coordination number of nine for the barium ion. Der strukturelle Aufbau und die atomaren Absta È nde beider Varianten sind anna È hernd gleich. Die Bariumatome haben die Koordinationszahl neun. Es werden propellerartige Anordnungen mit einem Chloridion in der Achse und den Fluoridionen als Flu È gel beobachtet. Die letzteren sind durch Kana È le von dreifach bekappten Fluoridprismen verbunden. Die Besetzung der fehlgeordneten Bariumlagen in den Kana È len der Fehlordnungsvariante ist der wesentliche Unterschied zwischen beiden Varianten. Die unerwartet hohe Ro È ntgendichte fu È r beide Formen von Ba 7 F 12 Cl 2 entspricht der Dichte anderer Bariumfluoridhalogenide mit der Koordinationszahl 9 fu È r das Bariumatom
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