4,529 research outputs found
Design and Performance of the CMS Pixel Detector Readout Chip
The readout chip for the CMS pixel detector has to deal with an enormous data
rate. On-chip zero suppression is inevitable and hit data must be buffered
locally during the latency of the first level trigger. Dead-time must be kept
at a minimum. It is dominated by contributions coming from the readout. To keep
it low an analog readout scheme has been adopted where pixel addresses are
analog coded. We present the architecture of the final CMS pixel detector
readout chip with special emphasis on the analog readout chain. Measurements of
its performance are discussed.Comment: 8 pages, 11 figures. Contribution to the Proceedings of the Pixel2005
Workshop, Bonn, German
Alignment transition in a nematic liquid crystal due to field-induced breaking of anchoring
We report on the alignment transition of a nematic liquid crystal from
initially homeotropic to quasi-planar due to field-induced anchoring breaking.
The initial homeotropic alignment is achieved by Langmuir-Blodgett monolayers.
In this geometry the anchoring strength can be evaluated by the Frederiks
transition technique. Applying an electric field above a certain threshold
provokes turbulent states denoted DSM1 and DSM2. While DSM1 does not affect the
anchoring, DSM2 breaks the coupling between the surface and the liquid crystal:
switching off the field from a DSM2 state does not immediately restore the
homeotropic alignment. Instead, we obtain a quasi-planar metastable alignment.
The cell thickness dependence for the transition is related to theComment: 7 pages, LaTeX2e article, 4 figures, 7 EPS files, added references,
accepted for publication in Europhysics Letter
Nanotrench for nano and microparticle electrical interconnects
We present a simple and versatile patterning procedure for the reliable and reproducible fabrication of high aspect ratio (10 4 ) electrical interconnects that have separation distances down to 20 nm and lengths of several hundreds of microns. The process uses standard optical lithography techniques and allows parallel processing of many junctions, making it easily scalable and industrially relevant. We demonstrate the suitability of these nanotrenches as electrical interconnects for addressing micro and nanoparticles by realizing several circuits with integrated species. Furthermore, low impedance metal-metal low contacts are shown to be obtained when trapping a single metal-coated microsphere in the gap, emphasizing the intrinsic good electrical conductivity of the interconnects, even though a wet process is used. Highly resistive magnetite-based nanoparticles networks also demonstrate the advantage of the high aspect ratio of the nanotrenches for providing access to electrical properties of highly resistive materials, with leakage current levels below 1 pA. © 2010 IOP Publishing Ltd
The unseen evidence of Reduced Ionicity: The elephant in (the) room temperature ionic liquids
A new device for determining the compression after impact strength in thin laminates
In this work a new device has been developed to estimate compression-after-impact (CAI) strength. This device allows the testing of laminates thinner than those recommended by CAI test standards. The proposed device is composed of a support structure, with a set of vertical ribs that stabilize the specimen during the test, increasing the buckling load. A numerical analysis was made to ensure that global buckling does not occur in the laminate during the CAI test, and that there is no interference with the damage area. Laminate specimens were tested with the proposed device and the ASTM device. For specimens 4.416 mm thick (thickness according to ASTM D7137 standard), the test results were similar with both devices. For thinner laminates, higher CAI strength was estimated with the proposed device than with the ASTM device, showing that the global buckling was delayed.The authors are indebted to the Foundation for Research,
Development and Application of Composite Materials (FIDAMC)
and Innovation Works (EADS) for the financial support of this work
(project Ilia). Also, the authors acknowledge the collaboration of
the mechanical laboratories in FIDAMC and in Department of
Continuum Mechanics and Structural Analysis of University
Carlos III of Madrid.Publicad
Reality Conditions and Ashtekar Variables: a Different Perspective
We give in this paper a modified self-dual action that leads to the
-ADM formalism without having to face the difficult second class
constraints present in other approaches (for example if one starts from the
Hilbert-Palatini action). We use the new action principle to gain some new
insights into the problem of the reality conditions that must be imposed in
order to get real formulations from complex general relativity. We derive also
a real formulation for Lorentzian general relativity in the Ashtekar phase
space by using the modified action presented in the paper.Comment: 22 pages, LATEX, Preprint CGPG-94/10-
Three-dimensional shear in granular flow
The evolution of granular shear flow is investigated as a function of height
in a split-bottom Couette cell. Using particle tracking, magnetic-resonance
imaging, and large-scale simulations we find a transition in the nature of the
shear as a characteristic height is exceeded. Below there is a
central stationary core; above we observe the onset of additional axial
shear associated with torsional failure. Radial and axial shear profiles are
qualitatively different: the radial extent is wide and increases with height
while the axial width remains narrow and fixed.Comment: 4 pages, 5 figure
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