1. Geant4 - a simulation toolkit - Makoto Asai (SLAC Computing Services) On behalf of the Geant4 Collaboration December 1 st, 2003 ACAT03 @ KEK

2. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT032 Contents  General introduction and brief history  Geant4 kernel  Geometry  Physics  Highlights of the new developments  Highlights of user applications  User support processes  Summary

3. General introduction and brief history

4. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT034 What is Geant4?  Geant4 is an object-oriented toolkit for simulation of elementary particles passing through and interacting with matter. It includes a complete range of functionality including tracking, geometry, physics models and hits.  Geant4's application area includes high energy and nuclear physics experiments, accelerator and shielding studies, space engineering, medical physics and several other fields.  Geant4 is the successor of GEANT3, the world-standard toolkit for HEP detector simulation. Geant4 is one of the first successful attempt to re-design a major package of HEP software for the next generation of experiments using an Object-Oriented environment.

5. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT035 Flexibility of Geant4  In order to meet wide variety of requirements from various application fields, a large degree of functionality and flexibility are provided.  Geant4 has many types of geometrical descriptions to describe most complicated and realistic geometries  CSG, BREP, Boolean  XML interface  The physics processes offered cover a comprehensive range including electromagnetic, hadronic and optical processes for a large set of long- lived particles in materials and elements, over a wide energy range. The applicable energy range begins, in some cases, from 100 eV and extends up to the TeV energy range.

6. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT036 Physics in Geant4  It is rather unrealistic to develop a uniform physics model to cover wide variety of particles and/or wide energy range.  Much wider coverage of physics comes from mixture of theory-driven, parameterized, and empirical formulae. Thanks to polymorphism mechanism, both cross-sections and models (final state generation) can be combined in arbitrary manners into one particular process.  Standard EM processes  Low energy EM processes  Hadronic processes  Photon/lepton-hadron processes  Optical photon processes  Decay processes  Shower parameterization  Event biasing technique

7. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT037 Geant4 – Its history and future  Dec ’94 - Project start  Apr ’97 - First alpha release  Jul ’98 - First beta release  Dec ’98 - Geant4 0.0 (first public) release  Jul ’99 - Geant4 0.1 release  …  Jun ’03 - Geant4 5.2 release  Dec 12 th, ’03 - Geant4 6.0 release (planned)  We currently provide two to three public releases and bimonthly beta releases in between public releases every year.

8. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT038 Geant4 Collaboration Collaborators also from non- member institutions, including Budker Inst. of Physics IHEP Protvino MEPHI Moscow Pittsburg University Helsinki Inst. Ph. PPARC Univ. Barcelona HARP Lebedev

9. Geant4 kernel

10. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0310 Geant4 kernel  Geant4 consists of 17 categories.  Independently developed and maintained by WG(s) responsible to each category.  Interfaces between categories (e.g. top level design) are maintained by the global architecture WG.  Geant4 Kernel  Handles run, event, track, step, hit, trajectory.  Provides frameworks of geometrical representation and physics processes. Geant4 ReadoutVisuali zation Persis tency Run Event Inter faces Tracking Digits + Hits Processes Track GeometryParticle Graphic _reps Material Intercoms Global

11. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0311 Tracking and processes  Geant4 tracking is general.  It is independent to  the particle type  the physics processes involving to a particle  It gives the chance to all processes  To contribute to determining the step length  To contribute any possible changes in physical quantities of the track  To generate secondary particles  To suggest changes in the state of the track  e.g. to suspend, postpone or kill it.

12. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0312 Processes in Geant4  In Geant4, particle transportation is a process as well, by which a particle interacts with geometrical volume boundaries and field of any kind.  Because of this, for example, shower parameterization process can take over from the ordinary transportation without modifying the transportation process.  Each particle has its own list of applicable processes. At each step, all processes listed are invoked to get proposed physical interaction lengths.  The process which requires the shortest interaction length (in space- time) limits the step.

13. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0313 Cuts in Geant4  A Cut in Geant4 is a production threshold.  Only for physics processes that have infrared divergence  Not tracking cut, which does not exist in Geant4  Energy threshold must be determined at which discrete energy loss is replaced by continuous loss  Old way:  Track primary particle until cut-off energy is reached, calculate continuous loss and dump it at that point, stop tracking primary  Create secondaries only above cut-off energy, or add to continuous loss of primary for less energetic secondaries  Geant4 way:  Specify range (which is converted to energy for each material) at which continuous loss begins, track primary particle one more step to make it down to zero range  Create secondaries only above specified range, or add to continuous loss of primary for less energetic secondaries

14. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0314 Energy cut vs. range cut  500 MeV/c proton in liq.Ar (4mm) / Pb (4mm) sampling calorimeter liq.ArPbliq.ArPb  Geant3 (energy cut)  Ecut = 450 keV  Geant4 (range cut)  Rcut = 1.5 mm  Corresponds to Ecut in liq.Ar = 450 keV, Ecut in Pb = 2 MeV

15. Geometry

16. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0316Volume  Three conceptual layers  G4VSolid -- shape, size  G4LogicalVolume -- daughter physical volumes, material, sensitivity, user limits, etc. material, sensitivity, user limits, etc.  G4VPhysicalVolume -- position, rotation  Hierarchal three layers of geometry description allows maximum reuse of information to minimize the use of memory space. G4Box G4Tubs G4VSolid G4VPhysicalVolume G4Material G4VSensitiveDetector G4PVPlacement G4PVParameterised G4VisAttributes G4LogicalVolume

17. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0317 Solid  Geant4 geometry module supports variety of representations of shapes.  CSG (Constructed Solid Geometry) solids  G4Box, G4Tubs, G4Cons, G4Trd, …  Analogous to simple GEANT3 CSG solids  Specific solids (CSG like)  G4Polycone, G4Polyhedra, G4Hype, …  BREP (Boundary REPresented) solids  G4BREPSolidPolycone, G4BSplineSurface, …  Any order surface  Boolean solids  G4UnionSolid, G4SubtractionSolid, …

18. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0318 Physical volume  G4PVPlacement 1 Placement = One Volume  A volume instance positioned once in its mother volume  G4PVParameterised 1 Parameterized = Many Volumes  Parameterized by the copy number  Shape, size, material, position and rotation can be parameterized, by implementing a concrete class of G4VPVParameterisation.  Reduction of memory consumption  G4PVReplica 1 Replica = Many Volumes  Slicing a volume into smaller pieces (if it has a symmetry)  G4ReflectionFactory 1 Placement = a set of Volumes  Generating a pair of placements of a volume and its reflected volume  Useful typically for end-cap calorimeter  G4AssemblyVolume 1 Placement = a set of Placements  Position a group of volumes

19. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0319 Smart voxelization  In case of Geant 3.21, the user had to carefully implement his/her geometry to maximize the performance of geometrical navigation.  While in Geant4, user’s geometry is automatically optimized to most suitable to the navigation. - "Voxelization"  For each mother volume, one-dimensional virtual division is performed.  Subdivisions (slices) containing same volumes are gathered into one.  Additional division again using second and/or third Cartesian axes, if needed.  "Smart voxels" are computed at initialisation time  When the detector geometry is closed  Does not require large memory or computing resources  At tracking time, searching is done in a hierarchy of virtual divisions

20. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0320 Geometry checking tools  An overlapping volume is a contained volume which actually protrudes from its mother volume  Volumes are also often positioned in a same volume with the intent of not provoking intersections between themselves. When volumes in a common mother actually intersect themselves are defined as overlapping  Geant4 does not allow for malformed geometries  The problem of detecting overlaps between volumes is bounded by the complexity of the solid models description  Utilities are provided for detecting wrong positioning  Graphical tools  Kernel run-time commands

21. Physics

22. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0322 Physics processes in Geant4  Each process can act at any of three space-time intervals  In time - At rest (e.g. decay at rest)  Continuously along a step (e.g. Cherenkov radiation)  At a point - at the end of the step (e.g. decay in flight)  “Along step actions” are applied cumulatively, while others are selectively applied.  A process can have more than one types of action according to its nature.  For example, Ionization process has Along and End step actions  Tracking handles each type of action in turn.  It loops over all processes with such a type of action.  The motivation for creating these categories of actions is to keep the tracking independent of the physics processes.  All seven combinations of actions are possible.  The traditional Continuous, Continuous-Discrete, Discrete and AtRest are found in these cases.  The ordering of processes is important in some cases.  e.g. Multiple scattering affects the step length.

23. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0323 Electromagnetic processes  Gammas :  Gamma-conversion, Compton scattering, Photo-electric effect  Leptons (e,  ), charged hadrons, ions :  Energy loss (Ionisation, Bremstrahlung) or PAI model energy loss, Multiple scattering, Transition radiation, Synchrotron radiation,  Optical photons :  Cerenkov, Rayleigh, Reflection, Refraction, Absorption, Scintillation  High energy   Alternative implementation  Standard EM package ignores the binding energy of electron to an atom, while Low Energy EM package takes it into account.  ‘Standard’ for applications that do not need to go below 1 KeV  ‘Low Energy’: down to 250eV (e+/  ), O(0.1  m) for hadrons

24. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0324 Multiple scattering Angle (deg)  Examples of comparisons:  15.7 MeV e- on gold foil Modelling & comparisons: L. Urban

25. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0325 Hadronic and Photolepton-hadron processes  Each hadronic process may have one or more cross section data sets, and final state production models associated with it. Each one has its own energy range of applicability.  The term “data set” is meant in a broad sense to be an object that encapsulates methods and data for calculating total cross sections.  The term “model” is meant in a broad sense to be an object that encapsulates methods and data for calculating final state products.

26. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0326 Parameterization and data driven models  Parameterization models on the fly  high energy inelastic (Aachen, CERN)  low energy inelastic, elastic, fission, capture (TRIUMF, UBC, CERN, SLAC)  Parameterization models for stopping particles  base line (TRIUMF, CHAOS)  mu- (TRIUMF, FIDUNA)  pi- (INFN, CERN, TRIUMF)  K- (Crystal Barrel, TRIUMF)  anti-protons (JLAB, CERN)  Electromagnetic transitions of the exotic atom prior to capture; effects of atomic binding. (Novosibirsk, ESA)  Data driven models  Low energy neutron transport (neutron_hp),  Radioactive decay (DERA, ESA)  photon evaporation (INFN)  elastic scattering (TRIUMF, U.Alberta, CERN)  internal conversion (ESA)  etc..

27. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0327 Theory driven models  Ultra-high energy models  Parton transport model (U.Frankfurt, in discussion)  High energy models  ‘Fritjof’ type string model (CERN)  Quark gluon String model (CERN)  Pythia(7) interface (Lund, CERN)  Intra-nuclear transport models (or replacements)  Hadronic cascade+pre-equilibrium model (HIP, CERN)  Binary and Bertini cascade models (HIP, CERN, Novosibirsk, SLAC)  QMD type models (CERN, Inst.Th.Phys. Frankfurt)  Chiral invariant phase-space decay model (JLAB, CERN, ITEP)  Partial Mars rewrite (Kyoto, Uvic, in collaboration with FNAL)  De-excitation  Evaporation, fission, multi-fragmentation, fermi-break-up (CMS)

28. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0328 Hadronic Model Inventory 1 MeV 10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV LEP HEP ( up to 20 TeV) Photon Evap Multifragment Fermi breakup Fission Evaporation Pre- compound Bertini cascade Binary cascade QG String (up to 100 TeV) MARS FTF String (up to 20 TeV) High precision neutron At rest Absorption  K, anti-p Photo-nuclear, electro-nuclear CHIPS (gamma) CHIPS LE pp, pn Rad. decay

29. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0329 Verification  The verification effort of the geant4 hadronic working group is grouped into several sections:  Inclusive cross-sections  Thin target comparisons  Verification of model components  Code comparisons (least effective)  Complete application tests  Robustness.  A few examples of each are given in the following slides.

30. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0330 Proton reaction total cross-section: J.P.Wellisch

31. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0331 Pion production examples, QGS: Rapidity distributions and invariant cross-section predictions in quark gluon string model 100 GeV pi+ on Gold 400GeV protons on Lithium

32. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0332 Forward peaks in proton induced neutron production Beryllium Aluminum Iron Lead 256 MeV data Neutrons at 7.5deg.

33. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0333  Production from 730 MeV p (Bertini Model)

34. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0334 Low energy neutron capture: gammas from 14 MeV capture on Uranium

35. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0335 Nuclear interactions with Geant4 versus experiment Phantom and experimental results from H.Paganetti, B.Gottschalk, Medical physics Vol. 30, No.7, 2003 10 -9 pC/incident proton Channel

36. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0336 Atlas HEC (e/  ratio)

37. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0337 CMS ECAL + HCAL testbeam GEANT3 - GEANT4 comparison 100 GeV pi+ ECAL+HCAL

38. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0338 "Educated guess" physics lists  In Geant4, the physics lists serve the same purpose as the "packages" (GHEISHA, FLUKA, GCALOR) in geant3.  Conceptually, the two are identical.  Both ways provide the physics and its modeling to an application.  Each "package" is built of a complete and consistent set of models  In Geant4, the number of "packages" is quite large. Each option comes with trade-offs in descriptive power and performance.  It simply became clear that writing a good physics list is not trivial, in particular when hadronic physics is involved.  It is nice to be able to exploit the full power in the flexibility and variety of hadronic physics modeling in geant4, but being forced to do so is not what we want.  It is also nice to have the physics transparently in front of the user and to exploit it in the best possible way, but being forced to understand everything is (very understandably) not what people want, either.  We have systematically accumulated experience with various combinations of cross-section and models over the past years. Today we provide a set of physics lists institutionalizing this knowledge.  "Educated guess" physics lists

39. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0339 Use-case driven packages  LCG simulation project.  HEP calorimetry.  HEP trackers.  'Average' collider detector  Low energy dosimetric applications with neutrons  low energy nucleon penetration shielding  linear collider neutron fluxes  high energy penetration shielding  medical and other life-saving neutron applications  low energy dosimetric applications  high energy production targets e.g. 400GeV protons on C or Be  medium energy production targets e.g. 15-50 GeV p on light targets  LHC neutron fluxes  low background experiments  Air shower applications (still working on this) Each package has several physics lists suitable to the use-case

40. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0340 Decay  A decay table is associated to the definition of each particle type.  A track can have a decay channel. If it has, it exactly decays through this channel without randomizing by the decay ratio.  This allows the user to import decay chains generated by physics generators such as Pythia, and rely on Geant4 tracking for such unstable particles. Primary particle list B0 K0L … B0 G4Track K0L … “pre-defined” decay channel

41. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0341 Optical processes  Geant4 has a particle named “Optical Photon”, which is distinguished from gamma. It interacts by optical processes.  Geant4 is an ideal framework for modeling the optics of scintillation and Cerenkov detectors and their associated light guides. This is founded in the toolkit's unique capability of commencing the simulation with the propagation of a charged particle and completing it with the detection of the ensuing optical photons on photo sensitive areas, all within the same event loop.  This functionality is now employed world-wide in experimental simulations as diverse as ALICE, ANTARES, AMANDA, Borexino, Icarus, LHCb, HARP, KOPIO, the Pierre Auger Observatory, and the GATE (Imaging in Nuclear Medicine) Collaboration.

42. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0342 Optical processes  Optical photons are generated if one or more of following processes are activated.  Cerenkov radiation,  Transition radiation,  Scintillation  Optical processes built in Geant4  Absorption,  Rayleigh scattering  Boundary Processes (reflection, refraction)  Optical properties, e.g. dielectric coefficient and surface smoothness, can be set to a volume.

43. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0343 Shower parameterization framework  Geant4 includes a built-in framework for shower parameterization scheme. Currently, the user has to concrete his/her own parameterization assigned to a logical volume, which is then called as an “envelop”.  Regardless of the existence of granular daughter geometry, a particle comes into the envelop can be fully treated by the shower parameterization process.  The user still have a dynamic choice to take his/her parameterization or to follow the ordinary tracking in the granular geometry.  The shower parameterization process can directly contact to a sensitive detector associating to the volume to produce more than one distributed hits.

44. Highlights of new developments

45. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0345 Event biasing in Geant4  Event biasing (variance reduction) technique is one of the most important requirements, which Geant4 collaboration is aware of.  This feature could be utilized by many application fields such as  Radiation shielding  Dosimetry  Since Geant4 is a toolkit and also all source code is open, the user can do whatever he/she wants.  CMS, ESA, Alice, and some other experiments have already had their own implementations of event biasing options.  It’s much better and convenient for the user if Geant4 itself provides most commonly used event biasing techniques.

46. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0346 Current features in Geant4  Partial MARS migration  n, p, pi, K (< 5 GeV)  Since Geant4 0.0  General particle source module  Primary particle biasing  Since Geant4 3.0  Radioactive decay module  Physics process biasing in terms of decay products and momentum distribution  Since Geant4 3.0  Cross-section biasing (partial) for hadronic physics  Since Geant4 3.0  Leading particle biasing  Since Geant4 4.0  Geometry based biasing  Weight associating with real volume or artificial volume  Since Geant4 5.0

47. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0347 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 I = 1.0I = 2.0 W=1.0 W=0.5 P = 0.5

48. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0348 Cuts per Region  Geant4 has had a unique and uniform production threshold (‘cut’) expressed in length (range of secondary).  For all volumes  One cut in range for each particle  By default is the same cut for all particles.  Consistency of the physics simulated  A volume with dense material will not dominate the simulation time at the expense of sensitive volumes with light material.  Yet appropriate length scales can vary greatly between different areas of a large detector  E.g. a vertex detector (5  m) and a muon detector (2.5 cm).  Having a unique (low) cut can create a performance penalty.  Requests from ATLAS, BABAR, CMS, LHCb, …, to allow several cuts  Enabling the tuning of production thresholds at the level of a sub- detector, i.e. region.  Cuts are applied only for gamma, electron and positron.  ‘Full release’ in Geant4 5.1 (end April, 2003)  Comparable run-time performance compared to global cuts.

49. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0349 Region  Introducing the concept of region.  Set of geometry volumes, typically of a sub-system;  Or any group of volumes;  A cut in range is associated to a region;  a different range cut for each particle is allowed in a region.  Typical Uses  barrel + end-caps of the calorimeter can be a region;  “Deep” areas of support structures can be a region. Region B Region B Default Region Region B Region A C C

50. Highlights of Users Applications

51. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0351 Geant4 in HEP  ATLAS (CERN-LHC)  22 x 22 x 44 m 3  15,000 ton  15,000 ton  4 million channels  40 MHz readout

52. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0352

53. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0353 View of CMS muon system Sliced view of CMS barrel detectors View of 180 Higgs event simulated in CMS Tracker detector CMS

54. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0354 A Typical event in the Testbeam Red lines: Charged particle Green lines : Optical Photons. LHCb

55. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0355 Geant4 for beam transportation

56. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0356

57. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0357

58. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0358 Gamma ray astronomy from 15 keV to 10 MeV  Launched 17 October 2002  Length 5 m, diameter 3.7 m, mass 4 tons INTEGRAL

59. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0359 INTEGRAL in the ESA/ESTEC test center INTEGRAL Geant4 model by University of Southampton

60. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0360 Space Environments and Effects Section International Space Station (ISS)

61. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0361 Space Radiation: Solar Events of October-November 2003! The effects of space radiation on spacecraft and on astronauts can be simulated with Geant4 Images by the ESA/NASA SOHO spacecraft

62. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0362 ESA Space Environment & Effects Analysis Section DESIRE (Dose Estimation by Simulation of the ISS Radiation Environment)  KTH Stockholm, ESTEC, EAC, NASA Johnson  Prediction of the ambient energetic particle environment (SPENVIS & additional models)  Construction of COLUMBUS geometry in Geant4  Radiation transport, including secondary particle production, through the geometry  Calculation of astronaut radiation doses

63. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0363

64. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0364

65. User Support

66. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0366 User Support  Geant4 Collaboration offers extensive user supports.  Documents  Examples  Users workshops  Tutorial courses  HyperNews and mailing list  Bug reporting system  Requirements tracking system  Daily “private” communications  New implementation - Technical Forum

67. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0367 Documents for users  One introduction and Five user manuals http://wwwasd.web.cern.ch/wwwasd/geant4/G4UsersDocuments/ Overview/html/index.html  Installation guide  User's guide for application developers  For a user who develops a simulation application using Geant4  User's guide for toolkit developers  For a user who develops a module which alternates or enhances some of geant4 functionalities  Physics reference manual  Detailed description of each physics process with information of references  Software reference manual  LXR source code browser maintained by TRIUMF and KEK.  Materials of past tutorials / presentations, HyperNews and Web pages maintained by developers also available via Geant4 official Web page.  "Geant4 general paper" - NIM A 506.

68. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0368 Examples  Along the code releases, Geant4 provides examples which help user's understanding of functionalities of Geant4 and are reusable as "skeletons" of user's application.  Three levels of examples  Novice examples :  Demonstrate most basic features  Extended examples :  Highlight some functionalities / use-cases in detail  Some examples require external package(s)  Advanced examples :  Most realistic applications  User's contributions

69. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0369 Geant4 users workshop  Users workshops were held or are going to be held hosted by several institutes for various user communities.  KEK - Dec.2000, Jul.2001, Mar.2002, Jul.2002, Mar.2003, Jul.2003  SLAC - Feb.2002  Spain (supported by INFN) - Jul.2002  CERN - Nov.2002  ESA/NASA - Jan.2003, May.2004  dedicated to space-related users  Helsinki - Oct.2003  Local workshops of one or two days were held or are planned at several places.

70. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0370 Geant4 tutorials / lectures  In addition to the users workshops, many tutorial courses and lectures with some discussion time slots were held for various user communities.  CERN School of Computing  Italian National School for HEP/Nuclear Physicists  MC2000, MCNEG workshop, IEEE NSS/MIC  KEK, SLAC, DESY, FNAL, INFN, Frascati, Karolinska, GranSasso, etc.  ATLAS, CMS, LHCb  Tutorials/lectures at universities  U.K. - Imperial  Italy - Genoa, Bologna, Udine, Roma, Trieste  Near future tutorial courses  KEK (Dec. 8 th -11 th, 2003)  Vanderbilt Univ. TN. USA (Jan. 11 th -13 th, 2004)  SLAC (Mar. 8 th -10 th, 2004)

71. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0371 HyperNews  HyperNews system was set up in April 2001

72. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0372 HyperNews  19 categories  Not only “user-developer”, but also “user-user” information exchanges are quite intensive.

73. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0373 HyperNews is quite active

74. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0374 Technical Forum  In the Technical Forum, the Geant4 Collaboration, its user community and resource providers discuss:  major user and developer requirements, user and developer priorities, software implementation issues, prioritized plans, physics validation issues, user support issues  The Technical Forum is open to all interested parties  To be held at least 4 times per year (in at least two locales)  The purpose of the forum is to:  Achieve, as much as possible, a mutual understanding of the needs and plans of users and developers.  Provide the Geant4 Collaboration with the clearest possible understanding of the needs of its users.  Promote the exchange of information about physics validation performed by Geant4 Collaborators and Geant4 users.  Promote the exchange of information about user support provided by Geant4 Collaborators and Geant4 user communities.  Next Technical Forum meeting @ CERN on February 5 th, 2004.

75. Geant4 : a simulation toolkit - M.Asai (SLAC) - Dec 01, 2003 @ACAT0375 Summary  Geant4 is a worldwide collaboration providing a tool for simulation of particles interacting with matter.  Geant4’s object-oriented modular structure allows a large degree of functionality and flexibility.  Geant4 can handle most complicated and realistic geometries.  Geant4 provides sets of alternative physics models so that users can choose appropriate models.  Geant4 is being used by not only high energy and nuclear physics but also accelerator physics, astrophysics, space science and medical and other applications.  Geant4 Collaboration offers extensive user supports. http://cern.ch/geant4/