Geant4 in production: status and developments John Apostolakis (CERN) Makoto Asai (SLAC) for the Geant4 collaboration

Geant4 in production : status and developments, CHEP Geant4’s in HEP, production ► HEP Experiments in large scale production  BaBar (2001)  CMS (2003)  ATLAS (2004)  LHCb (2004) ► Used in many existing experiments  KamLAND, Borexino, HARP, … ► Used to study future experiments  ILC, NA48/3 (PA326), …

Geant4 in production : status and developments, CHEP Geant4’s widespread use ► Imaging, radiotherapy, dosimetry  PET and SPECT imaging (GATE),  brachytherapy, hadrontherapy, ► Space: satelites and planetary missions  XMM, INTEGRAL, Bepe Colombo, LISA, … ► Radiation assessment, dosimetry  LHCb, Electronics (TCAD), …

Geant4 in production : status and developments, CHEP Geant4 improvements ► Improved stability of EM energy deposition, resolution  From revision of electron transport (Multiple scattering)  Enables better accuracy at higher cuts - with less CPU ► Extensions to geometry modeler ► Ability to revise many particle properties ► Refinements, improvements in hadronics ► Physics Lists

Geant4 in production : status and developments, CHEP Summary ► Improvements in multiple scattering process  Addressing issues with ‘electron transport’ ► Speedups for initialisation/navigation  Option to only re-optimise parts that change with run  New voxelisation options being studied for regular geometries ► Overlap checks at geometry construction ► Revised implementation of particles  Impacting advanced users, customizing ► Refinements in hadronic physics

FLUKA and the Virtual Monte Carlo Andreas Morsch For the ALICE Offline Group CERN, Geneva, Switzerland Computing in High Energy and Nuclear Physics February 2006, T.I.F.R., Mumbai, India

7 Integration of FLUKA into detector simulation frame-work Advantages  Full detector simulation and radiation studies using the same detailed geometry  Re-use of code for detector response simulation as already developed for Geant3 Integration has been achieved using the  Virtual Monte Interface 3 and  The Root geometry modeler TGeo

8 Virtual MC Concept Transport MC transparent to the user application   Base class TVirtualMC User Code VMC GEANT4 VMC Particles Hits GEANT4 GEANT3 Output FLUKA VMC FLUKA Input GEANT3 VMC TGeo

9 Virtual Monte Carlo (VMC) User Code VMC Virtual Geometrical Modeller G3 G3 transport G4 transport G4 FLUKA transport FLUKA Geometrical Modeller Reconstruction Visualisation

10 Validation Validation of geometry navigation via TGeo  Standard benchmark tests provided by FLUKA authors Technical validation of the VMC implementation  Comparison with G3 results Physics validation  Comparison with test-beam data

11 Electron transport in thin layers 1000 electrons at 1 MeV, EM cascades Same final random number after simulations with FLUKA native and TFluka The same for all 3 tested examples

12 FLUKA/G3 Comparison Good agreement where it is expected:  Photons in electromagnetic shower log 10 (step/cm) log 10 (E/GeV) FLUKA VMC G3 VMC

13 Comparison with test-beam data ongoing Silicon Pixel Detector

14 Conclusions FLUKA VMC implementation completed Testing well advanced  TGeo/FLUKA validation completed  Good agreement with G3 and Testbeam FLUKA VMC will be used in the next ALICE Physics data challenge

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