2,055 research outputs found
Scalable Database Access Technologies for ATLAS Distributed Computing
ATLAS event data processing requires access to non-event data (detector
conditions, calibrations, etc.) stored in relational databases. The
database-resident data are crucial for the event data reconstruction processing
steps and often required for user analysis. A main focus of ATLAS database
operations is on the worldwide distribution of the Conditions DB data, which
are necessary for every ATLAS data processing job. Since Conditions DB access
is critical for operations with real data, we have developed the system where a
different technology can be used as a redundant backup. Redundant database
operations infrastructure fully satisfies the requirements of ATLAS
reprocessing, which has been proven on a scale of one billion database queries
during two reprocessing campaigns of 0.5 PB of single-beam and cosmics data on
the Grid. To collect experience and provide input for a best choice of
technologies, several promising options for efficient database access in user
analysis were evaluated successfully. We present ATLAS experience with scalable
database access technologies and describe our approach for prevention of
database access bottlenecks in a Grid computing environment.Comment: 6 pages, 7 figures. To be published in the proceedings of DPF-2009,
Detroit, MI, July 2009, eConf C09072
Prototyping Virtual Data Technologies in ATLAS Data Challenge 1 Production
For efficiency of the large production tasks distributed worldwide, it is
essential to provide shared production management tools comprised of
integratable and interoperable services. To enhance the ATLAS DC1 production
toolkit, we introduced and tested a Virtual Data services component. For each
major data transformation step identified in the ATLAS data processing pipeline
(event generation, detector simulation, background pile-up and digitization,
etc) the Virtual Data Cookbook (VDC) catalogue encapsulates the specific data
transformation knowledge and the validated parameters settings that must be
provided before the data transformation invocation. To provide for local-remote
transparency during DC1 production, the VDC database server delivered in a
controlled way both the validated production parameters and the templated
production recipes for thousands of the event generation and detector
simulation jobs around the world, simplifying the production management
solutions.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 5 pages, 3 figures, pdf. PSN TUCP01
POOL File Catalog, Collection and Metadata Components
The POOL project is the common persistency framework for the LHC experiments
to store petabytes of experiment data and metadata in a distributed and grid
enabled way. POOL is a hybrid event store consisting of a data streaming layer
and a relational layer. This paper describes the design of file catalog,
collection and metadata components which are not part of the data streaming
layer of POOL and outlines how POOL aims to provide transparent and efficient
data access for a wide range of environments and use cases - ranging from a
large production site down to a single disconnected laptops. The file catalog
is the central POOL component translating logical data references to physical
data files in a grid environment. POOL collections with their associated
metadata provide an abstract way of accessing experiment data via their logical
grouping into sets of related data objects.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, 1 eps figure, PSN MOKT00
Measurement of W±W± vector-boson scattering and limits on anomalous quartic gauge couplings with the ATLAS detector
This paper presents the extended results of measurements of W±W±jj production and limits on anomalous quartic gauge couplings using 20.3 fb−1 of proton–proton collision data at √s=8 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with two leptons (e or μ) with the same electric charge and at least two jets are analyzed. Production cross sections are determined in two fiducial regions, with different sensitivities to the electroweak and strong production mechanisms. An additional fiducial region, particularly sensitive to anomalous quartic gauge coupling parameters α4 and α5, is introduced, which allows more stringent limits on these parameters compared to the previous ATLAS measurement
Search for pair production of heavy vector-like quarks decaying to high-p T W bosons and b quarks in the lepton-plus-jets final state in pp collisions at √s=13 TeV with the ATLAS detector
A search is presented for the pair production of heavy vector-like T quarks, primarily targeting the T quark decays to a W boson and a b-quark. The search is based on 36.1 fb−1 of pp collisions at s√=13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Data are analysed in the lepton-plus-jets final state, including at least one b-tagged jet and a large-radius jet identified as originating from the hadronic decay of a high-momentum W boson. No significant deviation from the Standard Model expectation is observed in the reconstructed T mass distribution. The observed 95% confidence level lower limit on the T mass are 1350 GeV assuming 100% branching ratio to Wb. In the SU(2) singlet scenario, the lower mass limit is 1170 GeV. This search is also sensitive to a heavy vector-like B quark decaying to Wt and other final states. The results are thus reinterpreted to provide a 95% confidence level lower limit on the B quark mass at 1250 GeV assuming 100% branching ratio to Wt; in the SU(2) singlet scenario, the limit is 1080 GeV. Mass limits on both T and B production are also set as a function of the decay branching ratios. The 100% branching ratio limits are found to be applicable to heavy vector-like Y and X production that decay to Wb and Wt, respectively
Primary Numbers Database for ATLAS Detector Description Parameters
We present the design and the status of the database for detector description
parameters in ATLAS experiment. The ATLAS Primary Numbers are the parameters
defining the detector geometry and digitization in simulations, as well as
certain reconstruction parameters. Since the detailed ATLAS detector
description needs more than 10,000 such parameters, a preferred solution is to
have a single verified source for all these data. The database stores the data
dictionary for each parameter collection object, providing schema evolution
support for object-based retrieval of parameters. The same Primary Numbers are
served to many different clients accessing the database: the ATLAS software
framework Athena, the Geant3 heritage framework Atlsim, the Geant4 developers
framework FADS/Goofy, the generator of XML output for detector description, and
several end-user clients for interactive data navigation, including web-based
browsers and ROOT. The choice of the MySQL database product for the
implementation provides additional benefits: the Primary Numbers database can
be used on the developers laptop when disconnected (using the MySQL embedded
server technology), with data being updated when the laptop is connected (using
the MySQL database replication).Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 6 pages, 5 figures, pdf. PSN MOKT00
Measurement of the inclusive jet cross-sections in proton-proton collisions at √s=8 TeV with the ATLAS detector
Inclusive jet production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of s√=8s=8 TeV recorded by the ATLAS experiment at the Large Hadron Collider at CERN. The total integrated luminosity of the analysed data set amounts to 20.2 fb−1. Double-differential cross-sections are measured for jets defined by the anti-kt jet clustering algorithm with radius parameters of R = 0.4 and R = 0.6 and are presented as a function of the jet transverse momentum, in the range between 70 GeV and 2.5 TeV and in six bins of the absolute jet rapidity, between 0 and 3.0. The measured cross-sections are compared to predictions of quantum chromodynamics, calculated at next-to-leading order in perturbation theory, and corrected for non-perturbative and electroweak effects. The level of agreement with predictions, using a selection of different parton distribution functions for the proton, is quantified. Tensions between the data and the theory predictions are observed
Searches for the Zγ decay mode of the Higgs boson and for new high-mass resonances in pp collisions at √s=13 TeV with the ATLAS detector
This article presents searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Zγ, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb−1 of pp collisions at s√=13 recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected — assuming Standard Model pp → H → Zγ production and decay) upper limit on the production cross section times the branching ratio for pp → H → Zγ is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level
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