Input data for applications that run in cloud computing centres can be stored at distant repositories, often with multiple copies of the popular data stored at many sites. Locating and retrieving the ...remote data can be challenging, and we believe that federating the storage can address this problem. A federation would locate the closest copy of the data on the basis of GeoIP information. Currently we are using the dynamic data federation Dynafed, a software solution developed by CERN IT. Dynafed supports several industry standards for connection protocols like Amazon's S3, Microsoft's Azure, as well as WebDAV and HTTP. Dynafed functions as an abstraction layer under which protocol-dependent authentication details are hidden from the user, requiring the user to only provide an X509 certificate. We have setup an instance of Dynafed and integrated it into the ATLAS data distribution management system. We report on the challenges faced during the installation and integration. We have tested ATLAS analysis jobs submitted by the PanDA production system and we report on our first experiences with its operation.
An optical calibration manipulator system Morris, D.; Amaudruz, P.-A.; Berghaus, F. ...
IEEE transactions on nuclear science,
06/2006, Letnik:
53, Številka:
3
Journal Article
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The K2K experiment at KEK is searching for neutrino oscillations by measuring the neutrino beam flux at both a 1 kilotonne water Cherenkov detector (front detector) close to the neutrino source, and ...at the Super Kamiokande detector 250 km away. Part of the optical calibration of the front detector is accomplished by transmitting laser light via a fiber optic cable to a light-diffusing ball immersed in the water. A manipulator system has been built to position the ball at various locations within the water volume. A description of the mechanics and the control system is presented.
We describe a high-throughput computing system for running jobs on public and private computing clouds using the HTCondor job scheduler and the cloudscheduler VM provisioning service. The distributed ...cloud computing system is designed to simultaneously use dedicated and opportunistic cloud resources at local and remote locations. It has been used for large-scale production particle physics workloads for many years using thousands of cores on three continents. A decade after its initial design and implementation, cloudscheduler has been modernized to take advantage of new software designs, improved operating system capabilities and support packages. The updated cloudscheduler is more resilient and scalable, with expanded capabilities. We present an overview of the original design and then describe the new version of the distributed compute cloud system. We conclude with a review of the current status and future plans.
The differential cross section for the process $Z/\gamma^*\rightarrow ll$ ($l=e,\mu$) as a function of dilepton invariant mass is measured in pp collisions at $\sqrt{s}=$7 TeV at the LHC using the ...ATLAS detector. The measurement is performed in the $e$ and $\mu$ channels for invariant masses between 26 GeV and 66 GeV using an integrated luminosity of 1.6 fb$^{-1}$ collected in 2011 and these measurements are combined. The analysis is extended to invariant masses as low as 12 GeV in the muon channel using 35 pb$^{-1}$ of data collected in 2010. The cross sections are determined within fiducial acceptance regions and corrections to extrapolate the measurements to the full kinematic range are provided. Next-to-next-to-leading-order QCD predictions provide a significantly better description of the results than next-to-leading-order QCD calculations, unless the latter are matched to a parton shower calculation.
The ATLAS detector has been designed for operation at the Large Hadron Collider at CERN. ATLAS includes electromagnetic and hadronic liquid argon calorimeters, with almost 200,000 channels of data ...that must be sampled at the LHC bunch crossing frequency of 40 MHz. The calorimeter electronics calibration and readout are performed by custom electronics developed specifically for these purposes. This paper describes the system performance of the ATLAS liquid argon calibration and readout electronics, including noise, energy and time resolution, and long term stability, with data taken mainly from full-system calibration runs performed after installation of the system in the ATLAS detector hall at CERN.
The production cross-section of B+ mesons is measured as a function of transverse momentum pT and rapidity y in proton--proton collisions at center-of-mass energy sqrt(s) = 7 TeV, using 2.4 fb-1 of ...data recorded with the ATLAS detector at the Large Hadron Collider. The differential production cross-sections, determined in the range 9
This paper presents the application of a variety of techniques to study jet substructure. The performance of various modified jet algorithms, or jet grooming techniques, for several jet types and ...event topologies is investigated for jets with transverse momentum larger than 300 GeV. Properties of jets subjected to the mass-drop filtering, trimming, and pruning algorithms are found to have reduced sensitivity to multiple proton-proton interactions, are more stable at high luminosity and improve the physics potential of searches for heavy boosted objects. Studies of the expected discrimination power of jet mass and jet substructure observables in searches for new physics are also presented. Event samples enriched in boosted W and Z bosons and top-quark pairs are used to study both the individual jet invariant mass scales and the efficacy of algorithms to tag boosted hadronic objects. The analyses presented use the full 2011 ATLAS dataset, corresponding to an integrated luminosity of 4.7 +/- 0.1 /fb from proton-proton collisions produced by the Large Hadron Collider at a center-of-mass energy of sqrt(s) = 7 TeV.
We performed an improved search for nu(mu) --> nu(e) oscillation with the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment, using the full data sample of 9.2 x 10(19) protons on ...target. No evidence for a nu(e) appearance signal was found, and we set bounds on the nu(mu) --> nu(e) oscillation parameters. At Deltam(2)=2.8 x 10(-3) eV(2), the best-fit value of the K2Knu(mu) disappearance analysis, we set an upper limit of sin(2)2theta(mue) < 0.13 at a 90% confidence level.
Mass and angular distributions of dijets produced in LHC proton-proton collisions at a centre-of-mass energy sqrt(s)=7 TeV have been studied with the ATLAS detector using the full 2011 data set with ...an integrated luminosity of 4.8/fb. Dijet masses up to 4.0 TeV have been probed. No resonance-like features have been observed in the dijet mass spectrum, and all angular distributions are consistent with the predictions of QCD. Exclusion limits on six hypotheses of new phenomena have been set at 95% CL in terms of mass or energy scale, as appropriate. These hypotheses include excited quarks below 2.83 TeV, colour octet scalars below 1.86 TeV, heavy W bosons below 1.68 TeV, string resonances below 3.61 TeV, quantum black holes with six extra space-time dimensions for quantum gravity scales below 4.11 TeV, and quark contact interactions below a compositeness scale of 7.6 TeV in a destructive interference scenario.
Hitherto unobserved long-lived massive particles with electric and/or colour charge are predicted by a range of theories which extend the Standard Model. In this Letter a search is performed at the ...ATLAS experiment for slow-moving charged particles produced in proton–proton collisions at 7 TeV centre-of-mass energy at the LHC, using a data-set corresponding to an integrated luminosity of 34 pb −1 . No deviations from Standard Model expectations are found. This result is interpreted in a framework of supersymmetry models in which coloured sparticles can hadronise into long-lived bound hadronic states, termed R -hadrons, and 95% CL limits are set on the production cross-sections of squarks and gluinos. The influence of R -hadron interactions in matter was studied using a number of different models, and lower mass limits for stable sbottoms and stops are found to be 294 and 309 GeV respectively. The lower mass limit for a stable gluino lies in the range from 562 to 586 GeV depending on the model assumed. Each of these constraints is the most stringent to date.
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