Geant4 in production: status and developments

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

2. 1. 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 2006

3. 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 2006

4. 2. 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 2006

5. 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 Geant4 in production : status and developments, CHEP 2006

6. FLUKA and the Virtual Monte Carlo Andreas Morsch For the ALICE Offline Group CERN, Geneva, Switzerland Computing in High Energy and Nuclear Physics 13-17 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 Interface3 and • The Root geometry modeler TGeo4 3http://root.cern.ch/root/vmc/VirtualMC.html 4http://root.cern.ch

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

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

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. log10(step/cm) FLUKA/G3 Comparison • Good agreement where it is expected: • Photons in electromagnetic shower FLUKA VMC G3 VMC log10(E/GeV)

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

20. Using Linux efficiently !