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     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                             Chem3
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This example is provided by the Geant4-DNA collaboration.

These processes and models are further described at:
http://geant4-dna.org

Any report or published results obtained using the Geant4-DNA software shall 
cite the following Geant4-DNA collaboration publications:
Phys. Med. 31 (2015) 861-874
Med. Phys. 37 (2010) 4692-4708

How to implement user actions in the chemistry module.

 1 - GEOMETRY DEFINITION

  It is a simple box which represents a 'semi infinite' homogeneous medium.

  Two parameters define the geometry :
   - the material of the box -- for Geant4-DNA it has to be water.
   - the full size of the box.

  The default geometry is constructed in DetectorConstruction class, but all of 
  the above parameters can be changed interactively via the commands defined in 
  the DetectorMessenger class.
 	
 2 - PHYSICS LIST
  
  The physics list is initialized in G4EmDNAChemistry, together with chemical
  stage models configuration.
 	 
 3 - AN EVENT: THE PRIMARY GENERATOR
 
  The primary kinematic consists of a single particle starting at the center of 
  the sphere. The type of the particle and its energy are set in the 
  PrimaryGeneratorAction class, and can be changed via the G4 build-in commands 
  of G4ParticleGun class.
  The chemistry module is triggered in the StackingAction class when all 
  physical tracks have been processed.

 4 - HOW TO START ?

  Run the example from this directory.
  The user interface will be launched. Continue using /run/beamOn 1 command.

 5 - OUTPUT

  Physics initialization and the defined reaction table are printed.
  G4ITStepManager processes the chemical stage time step after time step.
  Chemical reactions are printed.
  In the GUI window a cummulative trajectory of the chemical species is drawn.

 6 - TIME EVOLUTION VISUALIZATION

  User can start a visualization of the chemical track evolution in time and space
  using /control/execute movie.mac.
  Note, that in default setup the simulation requires machine with 6 GB of RAM.
  To lower memory requirements, either decrease energy of the incident electron
  in prep.mac or/and shorten the simulation using SetEndTime setting in 
  src/ActionInitialization.cc.

