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1. LHCb Grid Computing • LHCb is a particle physics experiment which will study the subtle differences between matter and antimatter • 500 scientists • 48 institutes • 14 countries Calorimeters Muon Detector Yoke Tracker Shielding Coil RICH-2 Moun Vertex RICH-1 1000 million short lived particles of matter and antimatter called B and B-bar mesons (which contain the b quark) will be studied each year. In order to design the detector and to understand the physics, many millions of simulated events also have to be produced. We are using Grid technology so that we can use computing resources distributed around the world to satisfy our requirements. LHCb has developed DIRAC, a software system which uses existing Grid networks, such as LCG. This allows the LHCb simulations to be running at the same time all over the world. In Europe, DIRAC will be run at: CERN, Lyon, Barcelona, Torino, Amersterdam, Karlsruhe, and other LCG sites. In the UK, LHCb computing and software centres are sited at the Universities of Bristol, Cambridge, Edinburgh, Glasgow, Imperial College, Liverpool & Oxford and at theRutherford Appleton Laboratory.

2. INI INI INI INI DB of LHCb Monte-Carlo Simulations 1 DIRAC accept jobs from the Simulation Database, and directly from Users. 1 With the assistance of collaborating DIRAC Services, the Agents fetch jobs from the Job DB when they detect available resources 2 Service B Service C Service A Service D Agent X Agent Y Agents submit jobs to batch queues 3 Grid File Catalog And Distributed Storage 4 Collect and transfer job output data to Grid Storage 5 Analyse results and improve models Ian Stokes-Rees, i.stokes-rees1@physics.ox.ac.uk