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Other GEANT4 capabilities

Other GEANT4 capabilities. Event biasing Parameterisation (fast simulation) Persistency Parallelisation and integration in a distributed computing environment. Fast simulation. Geant4 allows to perform full and fast simulation in the same environment.

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Other GEANT4 capabilities

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  1. Other GEANT4 capabilities Event biasing Parameterisation (fast simulation) Persistency Parallelisation and integration in a distributed computing environment

  2. Fast simulation Geant4 allows to perform full and fast simulation in the same environment • Theparameterisationprocess produces a direct detectorresponse, from the knowledge of particle and volume properties • hits, digis, reconstructed-like objects (tracks, clusters etc.) • Great flexibility • activate fast /full simulation by detector • example:full simulation for inner detectors, fast simulation for calorimeters • activate fast /full simulation by geometry region • example:fast simulation in central areas and full simulation near cracks • activate fast /full simulation by particle type • example:in e.m. calorimeter, e/g parameterisation + full simulation of hadrons • parallel geometries in fast/full simulation • example:inner and outer tracking detectors distinct in full simulation, but handled together in fast simulation

  3. Event biasing • Geant4 provides facilities for event biasing • The effect consists in producing a small number of secondaries, which are artificially recognized as a huge number of particles by their statistical weights • Event biasing can be used, for instance, for the transportation of slow neutrons or in the radioactive decay simulation • Various variance reduction techniques available

  4. Leading particle biasing • Simulating a full shower is an expensive calculation • Instead of generating a full shower, trace only the most energetic secondary • Other secondary particles are immediately killed before being stacked • Convenient way to roughly estimate, e.g. the thickness of a shield • Physical quantities such as energy are not conserved for each event

  5. I = 1.0 I = 2.0 W=0.5 W=0.5 W=1.0 P = 0.5 Geometrical importance biasing • Define importance for each geometrical region • Duplicate a track with half (or relative) weight if it goes toward more important region • Russian-roulette in another direction • Scoring particle flux with weights • at the surface of volumes

  6. Retrieve( ) Inherits from HepPersObj in HepODBMS Store( ) Persistency • Geant4 Persistency makes run, event, hits, digits and geometry information be persistent, to be read back later by user programs • no dependence on any specific persistency model • use industrial standard ODMG C++ binding and HepODBMS as persistency interface • Possibility to run in transient or persistent mode G4 kernel objects have corresponding “P” objects in G4Persistency G4Run G4PRun G4Event G4PEvent G4Hit G4PHit :: “Parallel World” approach Data members of transient and persistent objects are copied by Store( ) and Retrieve( )

  7. IRCC LAN Node01 SW I T C H Node02 Node03 Node04 Access to distributed computing • By design, Geant4 can be executed in more than one process/machine in parallel • Geant4 itself does not provide any mechanism of parallelisation • use external utilities IMRT An example of parallelisation of a Geant4 based medical application Geant4 Simulation and Anaphe Analysis on a dedicated Beowulf Cluster S. Chauvie et al., IRCC Torino,Siena 2002

  8. DIANE prototype for an intermediate layer between applications and the GRID Transparentaccess to a distributed computing environment Parallelisation Access to the GRID DIANE DIstributed ANalysis Environment Hide complex details of underlying technology R&D in progress for Large Scale Master-Worker Computing http://cern.ch/DIANE Developed by J. Moscicki, CERN

  9. Current #Grid setup (computing elements): 5000 events, 2 workers, 10 tasks (500 events each) - aocegrid.uab.es:2119/jobmanager-pbs-workq - bee001.ific.uv.es:2119/jobmanager-pbs-qgrid - cgnode00.di.uoa.gr:2119/jobmanager-pbs-workq - cms.fuw.edu.pl:2119/jobmanager-pbs-workq - grid01.physics.auth.gr:2119/jobmanager-pbs-workq - xg001.inp.demokritos.gr:2119/jobmanager-pbs-workq - xgrid.icm.edu.pl:2119/jobmanager-pbs-workq - zeus24.cyf-kr.edu.pl:2119/jobmanager-pbs-infinite - zeus24.cyf-kr.edu.pl:2119/jobmanager-pbs-long - zeus24.cyf-kr.edu.pl:2119/jobmanager-pbs-medium - zeus24.cyf-kr.edu.pl:2119/jobmanager-pbs-short - ce01.lip.pt:2119/jobmanager-pbs-qgrid Spain Greece Poland Portugal Parallel mode: distributed resources Parallel mode: local cluster DIANE framework and generic GRID middleware Traceback from a run of the Geant4 brachytherapy advanced example on CrossGrid testbed

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