The public project website together with a private collaboration site have been built and deployed on one of the technological platforms of the project. The rationale and technical choices behind this are described as well as the content... more
The public project website together with a private collaboration site have been built and deployed on one of the technological platforms of the project. The rationale and technical choices behind this are described as well as the content and functionality of the sites themselves.
CERN-LHC. Measurement of the dijet asymmetry in lead-lead collisions at a centre-of mass energy of 2.76 TeV/nucleon. The data sample, taken during the run of 2010 with a total integrated luminosity of 1.7 mub-1 is collected with a minimum... more
CERN-LHC. Measurement of the dijet asymmetry in lead-lead collisions at a centre-of mass energy of 2.76 TeV/nucleon. The data sample, taken during the run of 2010 with a total integrated luminosity of 1.7 mub-1 is collected with a minimum bias trigger. Jets are reconstructed using the anti-KT algorithm with R=0.4 with the underlying event background subtracted event-by-event. The leading jets are selected with maximum ET, with > 100 GeV for JET1 and > 25 GeV for JET2. The data are divided into 4 centrality regions and also compared with proton-proton data taken with the Atlas detector. DeltaPhi is the absolute difference in the azimuthal angles of the two leading jets. The Asymmetry is the difference in the transverse energies of the two leading jets divided by their sum for |DeltaPhi| < pi/2. Numerical values suppled by P Steinberg.
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the... more
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the azimuthal angular difference of the charged particle from the direction of the leading track. Toward is < 60 degrees, Away is > 120 degrees and Transverse is between 60 and 120 degrees. In each of these regions the charged particle multiplicity, PT density and average PT are measured.
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of... more
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of 2.3 pb-1, cover the J/PSI transverse momentum range from 1 to 70 GeV and |rapidity| < 2.4. The measurement uses the di-muon decay mode and is presented uncorrected for this. This record also contains data on the individual sources of systematic errors not tabulated in the paper.
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of... more
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of 2.3 pb-1, cover the J/PSI transverse momentum range from 1 to 70 GeV and |rapidity| < 2.4. The measurement uses the di-muon decay mode and is presented uncorrected for this. This record also contains data on the individual sources of systematic errors not tabulated in the paper.
CERN-LHC. A search for SUSY particles in 7 TeV proton-proton collisions in events with large missing transverse momentum and at least one heavy flavour jet. The data, with a total integrated luminosity of 35 pb-1, are analysed in the... more
CERN-LHC. A search for SUSY particles in 7 TeV proton-proton collisions in events with large missing transverse momentum and at least one heavy flavour jet. The data, with a total integrated luminosity of 35 pb-1, are analysed in the zero-lepton plus 3 jets and one-lepton plus 2 jet channels with at least one of the jets being a heavy flavour candidate. Jets are defined with the anti-Kt algorithm with R=0.4. In the zero-lepton data the effective mass (M(C=EFFECTIVE)) is defined as the scalar sum of the missing transverse energy and the transverse momenta of the highest PT jets. In the one-lepton data the transverse mas (MT) is constructed from the highest PT lepton and the missing ET.
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the... more
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the azimuthal angular difference of the charged particle from the direction of the leading track. Toward is < 60 degrees, Away is > 120 degrees and Transverse is between 60 and 120 degrees. In each of these regions the charged particle multiplicity, PT density and average PT are measured.
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the... more
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the azimuthal angular difference of the charged particle from the direction of the leading track. Toward is < 60 degrees, Away is > 120 degrees and Transverse is between 60 and 120 degrees. In each of these regions the charged particle multiplicity, PT density and average PT are measured.
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the... more
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the azimuthal angular difference of the charged particle from the direction of the leading track. Toward is < 60 degrees, Away is > 120 degrees and Transverse is between 60 and 120 degrees. In each of these regions the charged particle multiplicity, PT density and average PT are measured.
Open Data Science Mesh (CS3MESH4EOSC) is a newly funded project to create a new generation, interoperable federation of data and higher-level services to enable friction-free collaboration between European researchers. This new EU-funded... more
Open Data Science Mesh (CS3MESH4EOSC) is a newly funded project to create a new generation, interoperable federation of data and higher-level services to enable friction-free collaboration between European researchers. This new EU-funded project brings together 12 partners from the CS3 community (Cloud Synchronization and Sharing Services). The consortium partners include CERN, Danish Technical University (DK), SURFSARA (NL), Poznan Supercomputing Centre (PL), CESNET (CZ), AARNET (AUS), SWITCH (CH), University of Munster (DE), Ailleron SA (PL), Cubbit (IT), Joint Research Centre (BE) and Fundacion ESADE (ES). CERN acts as project coordinator. The consortium already operates services and storage-centric infrastructure for around 300 thousand scientists and researchers across the globe. The project will integrate these local existing sites and services into a seamless mesh infrastructure which is fully interconnected with the EOSC-Hub, as proposed in the European Commission's Impl...
Measurement of the muon charge asymmetry from W bosons produced in proton-proton collisions at a centre-of-mass energy of 7 TeV with ATLAS. The asymmetry is measured in the $W \to \mu \nu$ decay mode as a function of the muon... more
Measurement of the muon charge asymmetry from W bosons produced in proton-proton collisions at a centre-of-mass energy of 7 TeV with ATLAS. The asymmetry is measured in the $W \to \mu \nu$ decay mode as a function of the muon pseudorapidity using a data sample corresponding to a total integrated luminosity of 31 pb$^{-1}$.
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of... more
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of 2.3 pb-1, cover the J/PSI transverse momentum range from 1 to 70 GeV and |rapidity| < 2.4. The measurement uses the di-muon decay mode and is presented uncorrected for this. This record also contains data on the individual sources of systematic errors not tabulated in the paper.
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the... more
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the azimuthal angular difference of the charged particle from the direction of the leading track. Toward is < 60 degrees, Away is > 120 degrees and Transverse is between 60 and 120 degrees. In each of these regions the charged particle multiplicity, PT density and average PT are measured.
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of... more
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of 2.3 pb-1, cover the J/PSI transverse momentum range from 1 to 70 GeV and |rapidity| < 2.4. The measurement uses the di-muon decay mode and is presented uncorrected for this. This record also contains data on the individual sources of systematic errors not tabulated in the paper.
CERN-LHC. Study of events having final states with no leptons, jets and missing transverse momentum, and with no reconstructed electrons or muons, in proton-proton collisions at a centre-of-mass energy of 7 TeV. Data are selected with... more
CERN-LHC. Study of events having final states with no leptons, jets and missing transverse momentum, and with no reconstructed electrons or muons, in proton-proton collisions at a centre-of-mass energy of 7 TeV. Data are selected with various cuts and criteria to enhance different physics regions as described in the text of the paper. Exclusion limits on gluino and squark masses in SUSY models are presented for a simplified model (described in the paper) together with limits on m_0 and m_1/2 in MSUGRA/CMSSM models. The data sample has a total integrated luminosity of 35 pb-1 and shows no excess above the Standard Model background.
CERN-LHC. Search for SUSY in final states containing one isolated lepton (electron or muon), jets and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data sample, collected during 2010, has... more
CERN-LHC. Search for SUSY in final states containing one isolated lepton (electron or muon), jets and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data sample, collected during 2010, has a total integrated luminosity of 35 pb-1. No excess above the standard model is found. This record contains the distributions in missing ET, the transverse mass (MT) between the lepton and the missing transverse momentum vector, and the effective mass defined as the scalar sum of the pT of the three leading jets, the pT of the lepton and the missing ET. Also tabulated are the 95 PCT exclusion limits on m_0 and m_(1/2) for the MSUGRA/CMSSM model.
CERN-LHC. A search for SUSY particles in 7 TeV proton-proton collisions in events with large missing transverse momentum and at least one heavy flavour jet. The data, with a total integrated luminosity of 35 pb-1, are analysed in the... more
CERN-LHC. A search for SUSY particles in 7 TeV proton-proton collisions in events with large missing transverse momentum and at least one heavy flavour jet. The data, with a total integrated luminosity of 35 pb-1, are analysed in the zero-lepton plus 3 jets and one-lepton plus 2 jet channels with at least one of the jets being a heavy flavour candidate. Jets are defined with the anti-Kt algorithm with R=0.4. In the zero-lepton data the effective mass (M(C=EFFECTIVE)) is defined as the scalar sum of the missing transverse energy and the transverse momenta of the highest PT jets. In the one-lepton data the transverse mas (MT) is constructed from the highest PT lepton and the missing ET.
CERN-LHC. The data were recorded during 2010 with a total integrated luminosity of 35 pb-1. Exclusions at 95% CL are placed on two representative models. In the R-parity violating SUSY model, with tau sneutrinos and the leton flavour... more
CERN-LHC. The data were recorded during 2010 with a total integrated luminosity of 35 pb-1. Exclusions at 95% CL are placed on two representative models. In the R-parity violating SUSY model, with tau sneutrinos and the leton flavour violating model with zprime like vector bosons. The exclusion limits are tabulated here.
CERN-LHC. Measurement of the normalized distributions of absolute azimuthal angle difference between the two central jets with the highest transverse momenta produced in proton-proton collisions at a centre-of-mass energy of 7000 GeV. The... more
CERN-LHC. Measurement of the normalized distributions of absolute azimuthal angle difference between the two central jets with the highest transverse momenta produced in proton-proton collisions at a centre-of-mass energy of 7000 GeV. The measurement uses the complete 2010 dataset with an integrated luminosity of 36pb-1. Jets are reconstructed using the anti-kT algorithm with a radius of R=0.6 and required to have PT > 100 GeV and |y| < 2.8.
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of... more
CERN-LHC. Measurement of the inclusive J/PSI production cross section and the fraction of J/PSi produced in B-hadron decays from proton-proton collisions at a centre-of-mass energy of 7 TeV. The data, with a total integrated luminosity of 2.3 pb-1, cover the J/PSI transverse momentum range from 1 to 70 GeV and |rapidity| < 2.4. The measurement uses the di-muon decay mode and is presented uncorrected for this. This record also contains data on the individual sources of systematic errors not tabulated in the paper.
CERN-LHC. Measurement of the normalized distributions of absolute azimuthal angle difference between the two central jets with the highest transverse momenta produced in proton-proton collisions at a centre-of-mass energy of 7000 GeV. The... more
CERN-LHC. Measurement of the normalized distributions of absolute azimuthal angle difference between the two central jets with the highest transverse momenta produced in proton-proton collisions at a centre-of-mass energy of 7000 GeV. The measurement uses the complete 2010 dataset with an integrated luminosity of 36pb-1. Jets are reconstructed using the anti-kT algorithm with a radius of R=0.6 and required to have PT > 100 GeV and |y| < 2.8.
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the... more
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the azimuthal angular difference of the charged particle from the direction of the leading track. Toward is < 60 degrees, Away is > 120 degrees and Transverse is between 60 and 120 degrees. In each of these regions the charged particle multiplicity, PT density and average PT are measured.
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the... more
CERN-LHC. Measurement of charged particle distributions in proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data are collected with a minimum-bias trigger and are divided into three regions according to the azimuthal angular difference of the charged particle from the direction of the leading track. Toward is < 60 degrees, Away is > 120 degrees and Transverse is between 60 and 120 degrees. In each of these regions the charged particle multiplicity, PT density and average PT are measured.
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Research Interests:
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Research Interests: Computer Science, Physics, Nuclear Physics, Particle Physics, Monte Carlo, and 15 moreNuclear, Molecular, LHC, Large Hadron Collider, Data Collection, Physical, Atomic, Detector, Center of Mass, Monte Carlo Method, Photoproduction, ATLAS Detector, Distributions, Elementary Particles, and Charged Particles
Research Interests: Nuclear Physics, Particle Physics, Biology, High Energy Physics, Medicine, and 15 moreMultidisciplinary, Model, Large Hadron Collider, Luminosity, Nat, Elastic Scattering, American physical society, Cross Section, DDC, Forward Physics, Detector, Nature Communications, ATLAS Detector, Hard, and Atlas of human anatomy
Research Interests: Physics, Nuclear Physics, Quantum Physics, Particle Physics, Monte Carlo Simulation, and 14 moreElectronics, Construction, Liquid Argon, Nuclear, Molecular, Large Hadron Collider, Calibration, Data acquisition, Resolution, Atlas experiment, Atomic, Performance Measure, High energy, and Atlas of human anatomy
A web portal has been developed, in the context of the LCG/SPI project, in order to coordinate workflow and manage information in large software projects. It is a development of the GNU Savannah package and offers a range of services to... more
A web portal has been developed, in the context of the LCG/SPI project, in order to coordinate workflow and manage information in large software projects. It is a development of the GNU Savannah package and offers a range of services to every hosted project: Bug / support / patch trackers, a simple task planning system, news threads, and a download area for software releases. Features and functionality can be fine-tuned on a per project basis and the system displays content and grants permissions according to the user's status (project member, other Savannah user, or visitor). A highly configurable notification system is able to channel tracker submissions to developers in charge of specific project modules. The portal is based on the GNU Savannah package which is now developed as 'Savane' with the support of the Free Software Foundation France. It is a descendant of the well known SourceForge-2.0 software. The original trackers were contributed to the free software comm...
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The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate... more
The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing ...
Research Interests:
New cloud storage services allow groups of researchers to share, transfer and synchronize data in simple but powerful ways. Large-scale synchronization and sharing capabilities (typically above the 1-PB mark) are an opportunity for... more
New cloud storage services allow groups of researchers to share, transfer and synchronize data in simple but powerful ways. Large-scale synchronization and sharing capabilities (typically above the 1-PB mark) are an opportunity for innovative applications in scientific and technical areas, allowing for new forms of collaboration and to achieve results faster and more effectively. This is also a unique opportunity for IT departments to renew service offerings and to boost infrastructure by federating data repositories across collaborating sites and proposing/hosting new applications. The objective of this workshop is to share experiences and progress in cloud storage services. The usage of recently deployed services in the scientific community is rapidly expanding. Users are actively interested in new solutions for their growing data needs: new tools and enhanced data sharing capabilities enable new solutions. At the same time, the technology space is quickly evolving and many resear...
The case is made for a more user-centric and hierarchical structure than is seen in the current large-scale computing grids in high energy physics. The ideas presented are backed by real-life study of use cases on the Swiss ATLAS grid... more
The case is made for a more user-centric and hierarchical structure than is seen in the current large-scale computing grids in high energy physics. The ideas presented are backed by real-life study of use cases on the Swiss ATLAS grid prototype, covering 5 clusters at 3 academic institutions. 1
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Research Interests:
A measurement of the cross-section for ϒ(1S)→μ+μ−ϒ(1S)→μ+μ− production in proton–proton collisions at centre of mass energy of 7 TeV is presented. The cross-section is measured as a function of the ϒ(1S)ϒ(1S) transverse momentum in two... more
A measurement of the cross-section for ϒ(1S)→μ+μ−ϒ(1S)→μ+μ− production in proton–proton collisions at centre of mass energy of 7 TeV is presented. The cross-section is measured as a function of the ϒ(1S)ϒ(1S) transverse momentum in two bins of rapidity, |yϒ(1S)|&lt;1.2|yϒ(1S)|&lt;1.2 and 1.2&lt;|yϒ(1S)|&lt;2.41.2&lt;|yϒ(1S)|&lt;2.4. The measurement requires that both muons have transverse momentum pTμ&gt;4 GeV and pseudorapidity |ημ|&lt;2.5|ημ|&lt;2.5 in order to reduce theoretical uncertainties on the acceptance, which depend on the poorly known polarisation. The results are based on an integrated luminosity of 1.13 pb−1, collected with the ATLAS detector at the Large Hadron Collider. The cross-section measurement is compared to theoretical predictions: it agrees to within a factor of two with a prediction based on the NRQCD model including colour-singlet and colour-octet matrix elements as implemented in Pythia while it disagrees by up to a factor of ten with the next-to-leading order prediction based on the colour-singlet model.
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Research Interests:
Research Interests:
The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic... more
The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the second layer of the calorimeter are uniform at the level of 1.3% in the barrel and 2.8% in the endcaps. This leads to an estimated contribution to the constant term of% ...
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New metastable massive particles with electric and colour charge are features of many theories beyond the Standard Model. A search is performed for long-lived gluino-based R-hadrons with the ATLAS detector at the LHC using a data sample... more
New metastable massive particles with electric and colour charge are features of many theories beyond the Standard Model. A search is performed for long-lived gluino-based R-hadrons with the ATLAS detector at the LHC using a data sample corresponding to an integrated luminosity of 31 pb− 1. We search for evidence of particles that have come to rest in the ATLAS detector and decay at some later time during the periods in the LHC bunch structure without proton–proton collisions. No significant deviations from the expected ...
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The production of di-photon final states in protonproton collisions may occur through quark-antiquark t-channel annihilation, q" q!, or via gluon-gluon interactions, gg!, mediated by a quark box diagram. Despite the higher order of... more
The production of di-photon final states in protonproton collisions may occur through quark-antiquark t-channel annihilation, q" q!, or via gluon-gluon interactions, gg!, mediated by a quark box diagram. Despite the higher order of the latter, the two contributions are comparable, due to the large gluon flux at the LHC. Photon-parton production with photon radiation also contributes in processes such as q" q, gg! g, and qg! q. During the parton fragmentation process, more photons may also be produced. In this analysis, all such ...
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The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and... more
The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the relevant parameters that determine the quality of the muon measurement. We discuss the single element efficiency, resolution and noise rates, the ...
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A search is made for massive highly ionising particles with lifetimes in excess of 100 ns, with the ATLAS experiment at the Large Hadron Collider, using 3.1 pb− 1 of pp collision data taken at s= 7 TeV. The signature of energy loss in the... more
A search is made for massive highly ionising particles with lifetimes in excess of 100 ns, with the ATLAS experiment at the Large Hadron Collider, using 3.1 pb− 1 of pp collision data taken at s= 7 TeV. The signature of energy loss in the ATLAS inner detector and electromagnetic calorimeter is used. No such particles are found and limits on the production cross section for electric charges 6e⩽| q|⩽ 17e and masses 200 GeV⩽ m⩽ 1000 GeV are set in the range 1–12 pb for different hypotheses on the production mechanism.
The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with... more
The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and ...