282 research outputs found
AliEn Resource Brokers
AliEn (ALICE Environment) is a lightweight GRID framework developed by the
Alice Collaboration. When the experiment starts running, it will collect data
at a rate of approximately 2 PB per year, producing O(109) files per year. All
these files, including all simulated events generated during the preparation
phase of the experiment, must be accounted and reliably tracked in the GRID
environment. The backbone of AliEn is a distributed file catalogue, which
associates universal logical file name to physical file names for each dataset
and provides transparent access to datasets independently of physical location.
The file replication and transport is carried out under the control of the File
Transport Broker. In addition, the file catalogue maintains information about
every job running in the system. The jobs are distributed by the Job Resource
Broker that is implemented using a simplified pull (as opposed to traditional
push) architecture. This paper describes the Job and File Transport Resource
Brokers and shows that a similar architecture can be applied to solve both
problems.Comment: 5 pages, 8 figures, CHEP 03 conferenc
The Need for a Versioned Data Analysis Software Environment
Scientific results in high-energy physics and in many other fields often rely
on complex software stacks. In order to support reproducibility and scrutiny of
the results, it is good practice to use open source software and to cite
software packages and versions. With ever-growing complexity of scientific
software on one side and with IT life-cycles of only a few years on the other
side, however, it turns out that despite source code availability the setup and
the validation of a minimal usable analysis environment can easily become
prohibitively expensive. We argue that there is a substantial gap between
merely having access to versioned source code and the ability to create a data
analysis runtime environment. In order to preserve all the different variants
of the data analysis runtime environment, we developed a snapshotting file
system optimized for software distribution. We report on our experience in
preserving the analysis environment for high-energy physics such as the
software landscape used to discover the Higgs boson at the Large Hadron
Collider
Decontamination of incoming beef trimmings with hot lactic acid solution to improve microbial safety of resulting dry fermented sausages - A pilot study
PROOF as a Service on the Cloud: a Virtual Analysis Facility based on the CernVM ecosystem
PROOF, the Parallel ROOT Facility, is a ROOT-based framework which enables
interactive parallelism for event-based tasks on a cluster of computing nodes.
Although PROOF can be used simply from within a ROOT session with no additional
requirements, deploying and configuring a PROOF cluster used to be not as
straightforward. Recently great efforts have been spent to make the
provisioning of generic PROOF analysis facilities with zero configuration, with
the added advantages of positively affecting both stability and scalability,
making the deployment operations feasible even for the end user. Since a
growing amount of large-scale computing resources are nowadays made available
by Cloud providers in a virtualized form, we have developed the Virtual
PROOF-based Analysis Facility: a cluster appliance combining the solid CernVM
ecosystem and PoD (PROOF on Demand), ready to be deployed on the Cloud and
leveraging some peculiar Cloud features such as elasticity. We will show how
this approach is effective both for sysadmins, who will have little or no
configuration to do to run it on their Clouds, and for the end users, who are
ultimately in full control of their PROOF cluster and can even easily restart
it by themselves in the unfortunate event of a major failure. We will also show
how elasticity leads to a more optimal and uniform usage of Cloud resources.Comment: Talk from Computing in High Energy and Nuclear Physics 2013
(CHEP2013), Amsterdam (NL), October 2013, 7 pages, 4 figure
The MammoGrid Project Grids Architecture
The aim of the recently EU-funded MammoGrid project is, in the light of
emerging Grid technology, to develop a European-wide database of mammograms
that will be used to develop a set of important healthcare applications and
investigate the potential of this Grid to support effective co-working between
healthcare professionals throughout the EU. The MammoGrid consortium intends to
use a Grid model to enable distributed computing that spans national borders.
This Grid infrastructure will be used for deploying novel algorithms as
software directly developed or enhanced within the project. Using the MammoGrid
clinicians will be able to harness the use of massive amounts of medical image
data to perform epidemiological studies, advanced image processing,
radiographic education and ultimately, tele-diagnosis over communities of
medical "virtual organisations". This is achieved through the use of
Grid-compliant services [1] for managing (versions of) massively distributed
files of mammograms, for handling the distributed execution of mammograms
analysis software, for the development of Grid-aware algorithms and for the
sharing of resources between multiple collaborating medical centres. All this
is delivered via a novel software and hardware information infrastructure that,
in addition guarantees the integrity and security of the medical data. The
MammoGrid implementation is based on AliEn, a Grid framework developed by the
ALICE Collaboration. AliEn provides a virtual file catalogue that allows
transparent access to distributed data-sets and provides top to bottom
implementation of a lightweight Grid applicable to cases when handling of a
large number of files is required. This paper details the architecture that
will be implemented by the MammoGrid project.Comment: Talk PSN MOAT0005 from the 2003 Computing in High Energy and Nuclear
Physics (CHEP03), La Jolla, Ca, USA, March 2003, 6 pages, 4 figure
Evidence for an exotic S=-2, Q=-2 baryon resonance in proton-proton collisions at the CERN SPS
Results of resonance searches in the Xi - pi -, Xi - pi +, Xi -bar+ pi -, and Xi -bar+ pi + invariant mass spectra in proton-proton collisions at sqrt[s]=17.2 GeV are presented. Evidence is shown for the existence of a narrow Xi - pi - baryon resonance with mass of 1.862±0.002 GeV/c2 and width below the detector resolution of about 0.018 GeV/c2. The significance is estimated to be above 4.2 sigma . This state is a candidate for the hypothetical exotic Xi --3/2 baryon with S=-2, I=3 / 2, and a quark content of (dsdsu-bar). At the same mass, a peak is observed in the Xi - pi + spectrum which is a candidate for the Xi 03/2 member of this isospin quartet with a quark content of (dsusd-bar). The corresponding antibaryon spectra also show enhancements at the same invariant mass
System size and centrality dependence of the balance function in A+A collisions at sqrt[sNN]=17.2 GeV
Electric charge correlations were studied for p+p, C+C, Si+Si, and centrality selected Pb+Pb collisions at sqrt[sNN]=17.2 GeV with the NA49 large acceptance detector at the CERN SPS. In particular, long-range pseudorapidity correlations of oppositely charged particles were measured using the balance function method. The width of the balance function decreases with increasing system size and centrality of the reactions. This decrease could be related to an increasing delay of hadronization in central Pb+Pb collisions
A Roadmap for HEP Software and Computing R&D for the 2020s
Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade.Peer reviewe
Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions
We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe
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