1,325 research outputs found

    The RPC-based proposal for the ATLAS forward muon trigger upgrade in view of super-LHC

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    The innermost station of the present ATLAS forward muon detector needs to be upgraded for the super-LHC. We present a proposal to replace it with a sandwiched detector composed of several layers of small-radius Monitored Drift Tube chambers (sMDT) for precision tracking measurement and two stations of multi-gap Resistive Plate Chambers (mRPC) for triggering purpose. We describe the layout of the upgraded detector and the trigger strategy. Several modifications to the RPCs used in the ATLAS barrel region are needed to satisfy the super-LHC requirements. Various studies with the proposed mRPC timing resolution, spatial resolution and rate capability have been performed.Comment: 6 pages, 8 figures, proceeding for XI workshop on Resistive Plate Chambers and Related Detectors - RCP201

    Electroweak results from the ATLAS and CMS experiments

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    I summarize an extensive ATLAS and CMS electroweak physics program that involves a variety of single boson, diboson, triboson, and vector boson scattering measurements. The relevance of these studies to our understanding of the electroweak sector and electroweak symmetry breaking is emphasized. I describe the recent results and prospects for future measurements.Comment: 13 pages, 5 figures, Proceeding for the DPF meeting at the University of Michiga

    Diboson Production in Proton-Proton Collisions at s=7\sqrt{s}=7 TeV

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    This review article summarizes results on the production cross section measurements of electroweak boson pairs (WWWW, WZWZ, ZZZZ, WγW\gamma and ZγZ\gamma) at the Large Hadron Collider (LHC) in pppp collisions at a center-of-mass energy of s=7\sqrt{s}=7 \TeV. The two general-purpose detectors at the LHC, ATLAS and CMS, recorded an integrated luminosity of 5fb15fb^{-1} in 2011, which offered the possibility to study the properties of diboson production to high precision. These measurements test predictions of the Standard Model (SM) in a new energy regime and are crucial for the understanding and the measurement of the SM Higgs boson and other new particles. In this review, special emphasis is drawn on the combination of results from both experiments and a common interpretation with respect to state-of-the-art SM predictions.Comment: 60 page

    Recent Electroweak Results from the Tevatron

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    I present the recent electroweak measurements related to single W, Z boson and diboson productions from the CDF and D0 experiments at the Fermilab Tevatron collider.Comment: On the behalf of CDF and D0 collaborations, proceeding for 10th Conference on the Intersections of Particle and Nuclear Physic

    An investigation of PDMS structures for optimized ferroelectret performance

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    This paper reports the ANSYS simulation and fabrication processes for optimising PDMS ferroelectret performance. The proposed model extends the previously published analytical models and compares this with simulation of individual void geometry. The ferroelectret material is fabricated from PDMS using 3D-printed plastic moulds. The analytical model and Ansys simulation results predict the variation in performance of the PDMS ferroelectret with the different void geometry and surface charge density. The theoretical maximum piezoelectric coefficient d33 achieved was about 220 pC/N. The experimental maximum d33 obtained was 172 pC/N

    ELECTROKINETIC TRANSPORT AND MANIPULATION OF PARTICLES IN CURVED MICROCHANNELS

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    The investigation of electrokinetic particle transport in confined microchannels has practical significances in a variety of applications ranging from traditional gel electrophoresis to electrokinetic microfluidics-based lab-on-a-chip devices. To date, however, studies on particle electrokinetics have been limited to primarily theoretical or numerical analyses in straight microchannels of simple geometries. Very little work has been done on electrokinetic particle motions in real microchannels which usually consist of one or multiple turns. This thesis is dedicated to the fundamental and applied studies of electrokinetic transport and manipulation of particles in various curved microchannels using a combined experimental, theoretical, and numerical method. First, a fundamental study of particle electrokinetics in a microchannel U-turn, a typical unit in LOC devices, was investigated. A 2-D numerical model based on finite element method was developed to understand and predict the particle motion within the U-turn. It is demonstrated that particles are deflected to the outer wall of the turn by curvature-induced dielectrophoresis (termed cDEP) due to the locally intrinsic electric field gradients. Moreover, this lateral displacement increases with the rise of either the applied electric field or the particle size. Next, we utilize the cDEP in microchannel turns to implement a continuous electrokinetic focusing of particles in serpentine microchannels. Particles are demonstrated to gradually migrate to the centerline due to the periodically switched dielectrophoretic force they experience in a serpentine microchannel. This electrokinetic focusing favors large electric fields and large particles, and also increases when the number of serpentine periods increases. Such focusing also takes place in a spiral microchannel, where, however, particles are eventually focused to a stream flowing near the outer sidewall of the channel. Then, we explore the applications of cDEP to continuous electrokinetic separation of particles in curved microchannels. We develop two different approaches based on what we have acquired from the studies of particle electrokinetics in serpentine and spiral microchannels. The first approach employs a sheath flow to focus particles to one sidewall of a serpentine microchannel, where particles are then deflected to different flow paths by cDEP and thus sorted at the exit of serpentine section. We use this method to separate particles and cells by size at low DC electric fields. The second approach eliminates the sheath flow focusing of particles by the use of particle deflection and focusing in a double-spiral microchannel. Specifically, particles are focused by cDEP to one single stream near the outer wall of the first spiral, which is then displaced by cDEP and divided into two or more sub-streams in the second spiral, enabling the continuous sorting. We use this approach to implement the separation of particles by size and by charge, respectively. Moreover, we also demonstrate a continuous ternary separation of particle by size and charge simultaneously

    Ternary Inorganic Electrides with Mixed Bonding

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    A high-throughput screening based on first-principles calculations was performed to search for new ternary inorganic electrides. From the available materials database, we identified three new thermodynamically stable materials (Li12Mg3Si4, NaBa2O, and Ca5Ga2N4) as potential electrides made by main group elements, in addition to the well known mayenite based electride (C12A7:e−). Different from those conventional inorganic electrides in which the excess electrons play only the role of anions, the three new materials, resembling the electrides found in simple metals under high pressure, possess mixed ionic and metallic bonding. The interplay between two competing mechanisms, together with the different crystal packing motifs, gives rise to a variety of geometries in anionic electrons and rich physical phenomena such as ferromagnetism, superconductivity, and metal-insulator transition. Our finding here bridges the gap between electrides found at ambient and high-pressure conditions
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