• Introduction
• Download
• Available VMCs
• Examples
• Download
• Installation
• Meetings
• Presentations & Documents

The Virtual Monte Carlo (VMC) allows to run different simulation Monte Carlo without changing the user code and therefore the input and output format as well as the geometry and detector response definition.

The core of the VMC is the category of classes vmc in Root . It provides a set of interfaces which completely decouple the dependencies between the user code and the concrete Monte Carlo:

TVirtualMC TVirtualMCApplication TVirtualMCStack TVirtualMCDecayer

Interface to the concrete Monte Carlo program Interface to the user's Monte Carlo application Interface to the particle stack Interface to the external decayer

A user has to implement two mandatory classes: the MC application (derived from TVirtualMCApplication) and the MC stack (derived from TVirtualMCStack), optionally a user's external decayer (derived from TVirtualMCDecayer) can be introduced. The concrete Monte Carlo ( GEANT3 , Geant4 , FLUKA ) is selected at run time - when processing a ROOT macro where the concrete Monte Carlo is instantiated.

The relationships between the interfaces and their concrete realizations are illustrated in the class diagrams: User MC application , Virtual MC ,

At present time, VMC can be used with Geant3 and Geant4; the implementation for Fluka is under development.

Mailing list

The open list for discussing all aspects of the VMC project: vmc@root.cern.ch

You can join this list by sending a message to: majordomo@root.cern.ch with the body content:
subscribe vmc your_e-mail_address

Mailing list archive: VMC Digest

Available VMCs

For GEANT3 - geant3

For Geant4 - geant4_vmc

For FLUKA - fluka_vmc

Examples of VMC Applications

Examples

AliRoot

Download

Tar files (pro versions)

Tar files (old versions)

SVN

Download geant3:

Download geant4_vmc:

Download fluka_vmc:

Installation

Install geant3:

1. To install geant3 with Root v5.20/00, you have to specify your fortran compiler with the Root configure option:
   --with-f77=g77
   This setting will not be needed with newer Root versions.
   
   
2. geant3 requires Pythia6 library. You can follow Root installation instructions (see Pythia Event Generators paragraph) or directly the Pythia site.
   
   
3. Install geant3:
   cd geant3
   gmake

Install geant4_vmc:

1. Root has to be configured with g4root package; for this you have to specify the following configure options:
   --enable-g4root \
   --with-g4-incdir=$G4INSTALL/include \
   --with-g4-libdir=$G4INSTALL/lib/Linux-g++ \
   --with-clhep-incdir=$CLHEP_BASE_DIR/include \
   
   
2. To install Geant4 - see the Geant4 Web site how to do it.
   
   • Installation of Geant4 + Geant4 VMC requires CLHEP shared library.
     
   Note that for Geant4 VMC you will need:
   • Geant4 shared libraries;
     (set G4LIB_BUILD_SHARED environment variable to 1)
   • All Geant4 header files in the include directory
     
   • Build Geant4 with use G3toG4 tool
     (set G4LIB_USE_G3TOG4 environment variable to 1)
   These installation options are not set by default by the Configure program.
   
   
3. Since the version 2.0, you can choose to run Geant4 with Geant4 native geometry navigation or G4Root navigation.
   • To run with Geant4 native geometry navigation in case your geometry is defined via Root geometry package, you will have to install the Virtual Geometry Model (VGM) package See the VGM Web site how to do it.
     The VGM is used in Geant4 VMC for geometry in-memory conversion from Root TGeo objects to Geant4 native geometry. More details about this can be found at the Geant4 VMC Web page
   • To run with G4Root geometry navigation you need to build Root with g4root option, which is not activated by default, but required to compile Geant4 VMC libraries.
   
   
4. Set environment
   The following environment variables that defines the paths to used systems have to be set:

   ROOTSYS CLHEP_BASE_DIR G4INSTALL VGM_INSTALL USE_VGM

   Path to Root Path to CLHEP Path to Geant4 Path to VGM (optional) Set to 1 to build VGM dependent code

   
   
5. Install geant4_vmc:
   cd geant4_vmc/source
   gmake

Install fluka_vmc:

1. Root has to be configured with this option:
   --with-f77=g77
   to make sure that fluka_vmc will be built with the Fortran compiler supported by Fluka (gcc/g77).
   
   
2. To install FLUKA - see the FLUKA Web site how to do it.
   
   
3. Set environment
   The following environment variables that defines the paths to used systems have to be set:

   ROOTSYS FLUPRO FLUVMC

   Path to Root Path to FLUKA Path to Fluka VMC

   
   
4. Install fluka_vmc:
   cd fluka_vmc/source
   gmake

Install and run examples:

1. To install:
   The examples are provided within geant4_vmc package; to build all available examples:
   cd geant4_vmc/examples
   gmake
   The new macros for running examples with FLUKA are available only in the geant4_vmc development version, in the SVN trunk.
   
   
2. To run:
   
   • First, make sure that you have included all libraries path in your shared library path:
     your_path/root/lib
     your_path/geant4_vmc/lib/tgt_platform
     
     For G3 only:
     path to Pythia6 library
     your_path/geant3/lib/tgt_platform
     
     For G4 only:
     your_path/CLHEP/lib/
     your_path/geant4/lib/platform-compiler
     your_path/geant4_vmc/lib/tgt_platform
     optionally paths to external graphics libraries
     
     For FLUKA only:
     your_path/fluka_vmc/lib/tgt_platform
     
     
   • cd geant4_vmc/examples/E01 or E02 or E03
     root.exe
     root[0] .x run_g3.C or .x run_g4.C or .x run_fl.C

VMC Meetings

• VMC meeting, CERN, 04 February 2009
  
  
• VMC Open issues meeting, CERN, 22 September 2008
  
  
• VMC Workshop, CERN, 29-30th November 2004

Presentations & Documents

• Physics lists in Geant4 VMC
  presentation at ALICE-FAIR Computing Meeting, 28-29 April 2008, GSI
  
  
• The Geant4 Virtual Monte Carlo
  presentation at CHEP 2007, 2-9th September 2007, Victoria, Canada
  
  
• FLUKA and the Virtual Monte Carlo
  presentation at CHEP 2006, 13-17th February 2006, Mumbai, India
  
  
• Virtual MC
  
• TFluka MC interface
  presentations at International Workshop on Computing for Heavy Ion Physics, EMN 26 - 29 April 2005, France
  
  
• The Virtual MonteCarlo: status and applications
  presentation at CHEP 2004, 27 September 2004 to 01 October 2004, Interlaken, Switzerland
  
  
• Virtual Monte Carlo with Geant4: ALICE experience
  presentation at Geant4 Workshop 2003, 2 - 6 September 2003, TRIUMF, Vancouver Canada
  
  
• The Virtual MonteCarlo ( presentation , paper )
  presentation at CHEP 2003, 24 - 28 March 2003, La Jolla, California

The concept of Virtual MonteCarlo has been developed by the ALICE Software Project .
Authors: R.Brun, F.Carminati, I.Hrivnacova, A.Morsch.

Contact: vmc@root.cern.ch

Page maintained by: Ivana Hrivnacova
Last update: 20/01/2009