1,794 research outputs found
CRAB: a tool to enable CMS Distributed Analysis
No full textCRAB (Cms Remote Analysis Builder) is a tool, developed by INFN within the CMS collaboration, which provides to physicists the possibility to analyze large amount of data exploiting the huge computing power of grid distributed systems. It's currently used to analyze simulated data needed to prepare the Physics Technical Design Report. Data produced by CMS are distributed among several Computing Centers, and CRAB allows a generic users, without specific knowledge of grid infrastracture, to access and analyze those remote data, hiding the complexity of distributed computational services and making job submission and management as simple as in a local environment. The experience gained during the current CMS distributed data analysis effort is reported, along with CRAB ongoing developments. The interaction of CRAB with the actual and future CMS Data Management services is described, as well as the usage of WLCG/gLite/OSG middleware to provide access to different grid environments. Finally, the use within CRAB of BOSS for logging, bookkeeping and monitoring is presented
The CMS Muon System and Physics Performance
No full textThe CMS experiment will take data at the CERN LHC starting from 2007. The CMS muon system has been designed to identify, reconstruct and measure muons with high efficiency and accuracy. In this paper the layout of the system and the key features of the detectors are presented. The reconstruction algorithms, in the context of the High Level Trigger, and their performance in term of resolution, rate reduction and trigger efficiency are also discussed
Results on decays and measurement of and parameters in decay
No full textPhenomena beyond the standard model (SM) can manifest themself indirectly, by affecting the production and decay of SM particles.The features of decays are sensitive probes of physics beyond the Standard Model. This talk will review the results on these decays from the data collected by the CMS experiment. The decay is a flavor-changing neutral current (FCNC)process particularly sensitive to new physics, since it is heavily suppressed in the SM. Recent results from LHCb collaboration show a tension with respect SM prediction of more than 3 sigmas, and the Belle Collaboration reported a discrepancy almost as large.We will present results of an angular analysis done by the CMS experiment at the LHC, using p-p data collected at , corresponding to an integrated luminosity of . The analysis is focused to measure the angular parameter , as well as , as a function of the di-muons invariant mass
The laser calibration system of the TOP detector
No full textThe TOP detector at the Belle II Experiment is a particle identification detector, devoted mainly to the separation of charged pions and kaons. The charged particles emit Cherenkov photons when traversing a quartz radiator and these photons are converted inside micro-channel plates photomultipliers. The time of arrival and position of the photoelectrons, detected with excellent spatial and time resolution, are used to reconstruct the angle of the Cherenkov light emitted by the charged particle. The monitoring of the time stability and the measurement of the quantum efficiency of the photomultipliers are performed with a laser calibration system, with a target time resolution better than 50 ps. The system is a combination of a picosecond laser source, long single mode fibers, fiber bundles, and microlenses, which are needed to illuminate all the channels of the photomultipliers. A detailed description of the laser calibration system and its properties is given
CRAB, a Tool to Enable CMS Distributed Analysis
No full textThe CMS experiment will produce a large amount of data (few PBytes each year) that will be distributed over many computing centres spread in the countries participating to the CMS collaboration. To access and analyse data available at remote sites, physicists will use the grid infrastructure. CMS is developing a user friendly tool, CRAB (Cms Remote Analysis Builder), whose aim is to simplify the creation and the submission of analysis jobs into the grid environment. Its purpose is to hide the grid infrastructure complexity to final users, so that they can access remote data as easily as in a local environment. Data discovery, resources availability, status monitoring and output retrieval of submitted jobs are fully handled by CRAB. In this report we will explain how CRAB is interfaced with other CMS/grid services, the experience gained during production and future development
CRAB: A CMS application for distributed analysis
No full textBeginning in 2009, the CMS experiment will produce several petabytes of data each year which will be distributed over many computing centres geographically distributed in different countries. The CMS computing model defines how the data is to be distributed and accessed to enable physicists to efficiently run their analyses over the data. The analysis will be performed in a distributed way using Grid infrastructure. CRAB (CMS remote analysis builder) is a specific tool, designed and developed by the CMS collaboration, that allows the end user to transparently access distributed data. CRAB interacts with the local user environment, the CMS data management services and with the Grid middleware; it takes care of the data and resource discovery; it splits the user's task into several processes (jobs) and distributes and parallelizes them over different Grid environments; it performs process tracking and output handling. Very limited knowledge of the underlying technical details is required of the end user. The tool can be used as a direct interface to the computing system or can delegate the task to a server, which takes care of the job handling, providing services such as automatic resubmission in case of failures and notification to the user of the task status. Its current implementation is able to interact with gLite and OSG Grid middlewares. Furthermore, with the same interface, it enables access to local data and batch systems such as load sharing facility (LSF). CRAB has been in production and in routine use by end users since Spring 2004. It has been extensively used in studies to prepare the Physics Technical Design Report, in the analysis of reconstructed event samples generated during the Computing Software and Analysis Challenges and in the preliminary cosmic ray data taking. The CRAB architecture and the usage inside the CMS community will be described in detail, as well as the current status and future development
Automation of user analysis workflow in CMS
No full textCMS has a distributed computing model, based on a hierarchy of tiered regional
computing centres. However, the end physicist is not interested in the details of the computing
model nor the complexity of the underlying infrastructure, but only to access and use efficiently
and easily the remote services. The CMS Remote Analysis Builder (CRAB) is the official CMS
tool that allows the access to the distributed data in a transparent way. We present the current
development direction, which is focused on improving the interface presented to the user and
adding intelligence to CRAB such that it can be used to automate more and more the work
done on behalf of user. We also present the status of deployment of the CRAB system and the
lessons learnt in deploying this tool to the CMS collaboration
Recent Heavy Flavour results from CMS
No full textRecent results on b-flavour physics obtained by the CMS Collaboration will be presented. The flexible and poweful CMS trigger system allows the experiment to be sensitive to b-physics phenomena of different kinds, mostly in channels with muons in the final state. In this paper, some of these results will be reported, namely single quarkonia production, , as well as observation of double prompt production. The lifetimes of different states, , , , , , and will be described. Other measurement includes polarization, search for , and rare decay . Finally, the recent measurement of some angular parameters of the decay will be reviewed
Search for Dark Matter at LHC
No full textA review of the potential of the LHC experiments to discover and measure supersymmetric Dark Matter is presented. Different methods for sparticle mass spectrum reconstruction in the framework of R-Parity conserved mSUGRA model are discussed
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