5,150 research outputs found

    Computational relativistic quantum dynamics and its application to relativistic tunneling and Kapitza-Dirac scattering

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    Computational methods are indispensable to study the quantum dynamics of relativistic light-matter interactions in parameter regimes where analytical methods become inapplicable. We present numerical methods for solving the time-dependent Dirac equation and the time-dependent Klein-Gordon equation and their implementation on high performance graphics cards. These methods allow us to study tunneling from hydrogen-like highly charged ions in strong laser fields and Kapitza-Dirac scattering in the relativistic regime

    NASA Thesaurus supplement: A four part cumulative supplement to the 1988 edition of the NASA Thesaurus (supplement 3)

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    The four-part cumulative supplement to the 1988 edition of the NASA Thesaurus includes the Hierarchical Listing (Part 1), Access Vocabulary (Part 2), Definitions (Part 3), and Changes (Part 4). The semiannual supplement gives complete hierarchies and accepted upper/lowercase forms for new terms

    Hadron Spectrum from Lattice QCD

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    A brief review is given of the lattice QCD calculation of the hadron spectrum. The status of current attempts toward inclusion of dynamical up, down and strange quarks is summarized focusing on our own work. Recent work on the possible existence of pentaquark states are assessed. We touch upon the PACS-CS Project for building our next machine for lattice QCD, and conclude with a near-term physics and machine prospects.Comment: Talk given at the International Conference on QCD and Hadronic Physics, Beijing, June 16-20, 2005. References added and correcte

    Single particle detection of protein molecules using dark-field microscopy to avoid signals from nonspecific adsorption

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    A massively parallel single particle sensing method based on core-satellite formation of Au nanoparticles was introduced for the detection of interleukin 6 (IL-6). This method exploits the fact that the localized plasmon resonance (LSPR) of the plasmonic nanoparticles will change as a result of core-satellite formation, resulting in a change in the observed color. In this method, the hue (color) value of thousands of 67 nm Au nanoparticles immobilized on a glass coverslip surface is analyzed by a Matlab code before and after the addition of reporter nanoparticles containing IL-6 as target protein. The average hue shift as the result of core-satellite formation is used as the basis to detect small amount of proteins. This method enjoys two major advantages. First it is able to analyze the hue values of thousands of nanoparticles in parallel in less than a minute. Secondly the method is able to circumvent the effect of non-specific adsorption, a major issue in the field of biosensing

    Computational Particle Physics for Event Generators and Data Analysis

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    High-energy physics data analysis relies heavily on the comparison between experimental and simulated data as stressed lately by the Higgs search at LHC and the recent identification of a Higgs-like new boson. The first link in the full simulation chain is the event generation both for background and for expected signals. Nowadays event generators are based on the automatic computation of matrix element or amplitude for each process of interest. Moreover, recent analysis techniques based on the matrix element likelihood method assign probabilities for every event to belong to any of a given set of possible processes. This method originally used for the top mass measurement, although computing intensive, has shown its power at LHC to extract the new boson signal from the background. Serving both needs, the automatic calculation of matrix element is therefore more than ever of prime importance for particle physics. Initiated in the eighties, the techniques have matured for the lowest order calculations (tree-level), but become complex and CPU time consuming when higher order calculations involving loop diagrams are necessary like for QCD processes at LHC. New calculation techniques for next-to-leading order (NLO) have surfaced making possible the generation of processes with many final state particles (up to 6). If NLO calculations are in many cases under control, although not yet fully automatic, even higher precision calculations involving processes at 2-loops or more remain a big challenge. After a short introduction to particle physics and to the related theoretical framework, we will review some of the computing techniques that have been developed to make these calculations automatic. The main available packages and some of the most important applications for simulation and data analysis, in particular at LHC will also be summarized.Comment: 19 pages, 11 figures, Proceedings of CCP (Conference on Computational Physics) Oct. 2012, Osaka (Japan) in IOP Journal of Physics: Conference Serie

    CELES: CUDA-accelerated simulation of electromagnetic scattering by large ensembles of spheres

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    CELES is a freely available MATLAB toolbox to simulate light scattering by many spherical particles. Aiming at high computational performance, CELES leverages block-diagonal preconditioning, a lookup-table approach to evaluate costly functions and massively parallel execution on NVIDIA graphics processing units using the CUDA computing platform. The combination of these techniques allows to efficiently address large electrodynamic problems (>104>10^4 scatterers) on inexpensive consumer hardware. In this paper, we validate near- and far-field distributions against the well-established multi-sphere TT-matrix (MSTM) code and discuss the convergence behavior for ensembles of different sizes, including an exemplary system comprising 10510^5 particles

    CELES: CUDA-accelerated simulation of electromagnetic scattering by large ensembles of spheres

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    partially_open5sìCELES is a freely available MATLAB toolbox to simulate light scattering by many spherical particles. Aiming at high computational performance, CELES leverages block-diagonal preconditioning, a lookup-table approach to evaluate costly functions and massively parallel execution on NVIDIA graphics processing units using the CUDA computing platform. The combination of these techniques allows to efficiently address large electrodynamic problems (> 10(4) scatterers) on inexpensive consumer hardware. In this paper, we validate near- and far-field distributions against the well-established multi-sphere T-matrix (MSTM) code and discuss the convergence behavior for ensembles of different sizes, including an exemplary system comprising 10(5) particles. (C) 2017 Elsevier Ltd. All rights reserved.openhttps://github.com/disordered-photonics/celesEgel, A; Pattelli, L; Mazzamuto, G; Wiersma, DS; Lemmer, UEgel, A; Pattelli, L; Mazzamuto, G; Wiersma, Ds; Lemmer,
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