906 research outputs found
Phenomenology Tools on Cloud Infrastructures using OpenStack
We present a new environment for computations in particle physics
phenomenology employing recent developments in cloud computing. On this
environment users can create and manage "virtual" machines on which the
phenomenology codes/tools can be deployed easily in an automated way. We
analyze the performance of this environment based on "virtual" machines versus
the utilization of "real" physical hardware. In this way we provide a
qualitative result for the influence of the host operating system on the
performance of a representative set of applications for phenomenology
calculations.Comment: 25 pages, 12 figures; information on memory usage included, as well
as minor modifications. Version to appear in EPJ
Distributed Analysis within the LHC computing Grid
The distributed data analysis using Grid resources is one of the funda- mental applications in high energy physics to be addressed and realized before the start of LHC data taking. The needs to manage the resources are very high. In every experiment up to a thousand physicist will be submitting analysis jobs into the Grid. Appropriate user interfaces and helper applications have to be made available to assure that all users can use the Grid without too much expertise in Grid technology. These tools enlarge the number of Grid users from a few production adminis- trators to potentially all participating physicists. The GANGA job management system (http://cern.ch/ganga), devel- oped as a common project between the ATLAS and LHCb experiments provides and integrates these kind of tools. GANGA provides a sim- ple and consistent way of preparing, organizing and executing analysis tasks within the experiment analysis framework, implemented through a plug-in system. It allows trivial switching between running test jobs on a local batch system and running large-scale analyzes on the Grid, hiding Grid technicalities. We will be reporting on the plug-ins and our experiences of distributed data analysis using GANGA within the ATLAS experiment and the EGEE/LCG infrastructure. The integration and interaction with the ATLAS data management system DQ2/DDM into GANGA is a key functionality. In combination with the job splitting mechanism large amounts of analysis jobs can be sent to the locations of data following the ATLAS computing model. GANGA supports tasks of user analysis with reconstructed data and small scale production of Monte Carlo data
Big Data in Critical Infrastructures Security Monitoring: Challenges and Opportunities
Critical Infrastructures (CIs), such as smart power grids, transport systems,
and financial infrastructures, are more and more vulnerable to cyber threats,
due to the adoption of commodity computing facilities. Despite the use of
several monitoring tools, recent attacks have proven that current defensive
mechanisms for CIs are not effective enough against most advanced threats. In
this paper we explore the idea of a framework leveraging multiple data sources
to improve protection capabilities of CIs. Challenges and opportunities are
discussed along three main research directions: i) use of distinct and
heterogeneous data sources, ii) monitoring with adaptive granularity, and iii)
attack modeling and runtime combination of multiple data analysis techniques.Comment: EDCC-2014, BIG4CIP-201
Survey and Analysis of Production Distributed Computing Infrastructures
This report has two objectives. First, we describe a set of the production
distributed infrastructures currently available, so that the reader has a basic
understanding of them. This includes explaining why each infrastructure was
created and made available and how it has succeeded and failed. The set is not
complete, but we believe it is representative.
Second, we describe the infrastructures in terms of their use, which is a
combination of how they were designed to be used and how users have found ways
to use them. Applications are often designed and created with specific
infrastructures in mind, with both an appreciation of the existing capabilities
provided by those infrastructures and an anticipation of their future
capabilities. Here, the infrastructures we discuss were often designed and
created with specific applications in mind, or at least specific types of
applications. The reader should understand how the interplay between the
infrastructure providers and the users leads to such usages, which we call
usage modalities. These usage modalities are really abstractions that exist
between the infrastructures and the applications; they influence the
infrastructures by representing the applications, and they influence the ap-
plications by representing the infrastructures
From Lagrangians to Events: Computer Tutorial at the MC4BSM-2012 Workshop
This is a written account of the computer tutorial offered at the Sixth
MC4BSM workshop at Cornell University, March 22-24, 2012. The tools covered
during the tutorial include: FeynRules, LanHEP, MadGraph, CalcHEP, Pythia 8,
Herwig++, and Sherpa. In the tutorial, we specify a simple extension of the
Standard Model, at the level of a Lagrangian. The software tools are then used
to automatically generate a set of Feynman rules, compute the invariant matrix
element for a sample process, and generate both parton-level and fully
hadronized/showered Monte Carlo event samples. The tutorial is designed to be
self-paced, and detailed instructions for all steps are included in this
write-up. Installation instructions for each tool on a variety of popular
platforms are also provided.Comment: 58 pages, 1 figur
Storage Resource Manager version 2.2: design, implementation, and testing experience
Storage Services are crucial components of the Worldwide LHC Computing Grid Infrastructure spanning more than 200 sites and serving computing and storage resources to the High Energy Physics LHC communities. Up to tens of Petabytes of data are collected every year by the four LHC experiments at CERN. To process these large data volumes it is important to establish a protocol and a very efficient interface to the various storage solutions adopted by the WLCG sites. In this work we report on the experience acquired during the definition of the Storage Resource Manager v2.2 protocol. In particular, we focus on the study performed to enhance the interface and make it suitable for use by the WLCG communities. At the moment 5 different storage solutions implement the SRM v2.2 interface: BeStMan (LBNL), CASTOR (CERN and RAL), dCache (DESY and FNAL), DPM (CERN), and StoRM (INFN and ICTP). After a detailed inside review of the protocol, various test suites have been written identifying the most effective set of tests: the S2 test suite from CERN and the SRM-Tester test suite from LBNL. Such test suites have helped verifying the consistency and coherence of the proposed protocol and validating existing implementations. We conclude our work describing the results achieved
The iEBE-VISHNU code package for relativistic heavy-ion collisions
The iEBE-VISHNU code package performs event-by-event simulations for
relativistic heavy-ion collisions using a hybrid approach based on
(2+1)-dimensional viscous hydrodynamics coupled to a hadronic cascade model. We
present the detailed model implementation, accompanied by some numerical code
tests for the package. iEBE-VISHNU forms the core of a general theoretical
framework for model-data comparisons through large scale Monte-Carlo
simulations. A numerical interface between the hydrodynamically evolving medium
and thermal photon radiation is also discussed. This interface is more
generally designed for calculations of all kinds of rare probes that are
coupled to the temperature and flow velocity evolution of the bulk medium, such
as jet energy loss and heavy quark diffusion.Comment: 47 pages, 21 figures. Manuscript was accepted by Computer Physics
Communication
A new relativistic hydrodynamics code for high-energy heavy-ion collisions
We construct a new Godunov type relativistic hydrodynamics code in Milne
coordinates, using a Riemann solver based on the two-shock approximation which
is stable under the existence of large shock waves. We check the correctness of
the numerical algorithm by comparing numerical calculations and analytical
solutions in various problems, such as shock tubes, expansion of matter into
the vacuum, the Landau-Khalatnikov solution, and propagation of fluctuations
around Bjorken flow and Gubser flow. We investigate the energy and momentum
conservation property of our code in a test problem of longitudinal
hydrodynamic expansion with an initial condition for high-energy heavy-ion
collisions. We also discuss numerical viscosity in the test problems of
expansion of matter into the vacuum and conservation properties. Furthermore,
we discuss how the numerical stability is affected by the source terms of
relativistic numerical hydrodynamics in Milne coordinates.Comment: 20 pages, 16 figure
Flow in AA and pA as an interplay of fluid-like and non-fluid like excitations
To study the microscopic structure of quark-gluon plasma, data from hadronic
collisions must be confronted with models that go beyond fluid dynamics. Here,
we study a simple kinetic theory model that encompasses fluid dynamics but
contains also particle-like excitations in a boost invariant setting with no
symmetries in the transverse plane and with large initial momentum asymmetries.
We determine the relative weight of fluid dynamical and particle like
excitations as a function of system size and energy density by comparing
kinetic transport to results from the 0th, 1st and 2nd order gradient expansion
of viscous fluid dynamics. We then confront this kinetic theory with data on
azimuthal flow coefficients over a wide centrality range in PbPb collisions at
the LHC, in AuAu collisions at RHIC, and in pPb collisions at the LHC. Evidence
is presented that non-hydrodynamic excitations make the dominant contribution
to collective flow signals in pPb collisions at the LHC and contribute
significantly to flow in peripheral nucleus-nucleus collisions, while
fluid-like excitations dominate collectivity in central nucleus-nucleus
collisions at collider energies.Comment: 28 pages, 16 figure
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