
///\file "eventgenerator/exgps/.README.txt"
///\brief Example exgps README page

/*! \page Exampleexgps Example exgps 

  exgps is created to demonstrate the usage of G4GeneralParticleSource
  for generating  primary particle according to user defined distributions.
  These range from simple monocromatic point source to complicated mutiple
  sources with various biasing schemes. 
  
  http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides
        /ForApplicationDeveloper/html/ch02s07.html
   
   
  \section exgps_s1 GEOMETRY

  Simple geometry consists of a "Vacuum" world and, in it, two other components:
    - An alunimium box : 20 x 20 x 20 cm in size, cerntered at the origin.
    - A SiO2 sphere (radius 5 cm) is placed at the centre of the aluminium box.

  \section exgps_s2  PHYSICS

  Tranportation process only for all particles.

  \section exgps_s3 EVENT

  The event generator is the G4GeneralParticleSource (GPS). The instantiation of
  G4GeneralParticleSource is same as that for G4ParticleGun. 
  See the exGPSPrimaryGeneratorAction.cc file for details.  
  
  \section exgps_s4 VISUALIZATION
 
  Visualisation of the geometry and the tracks is possible with many of the 
  G4 visualisation packages.
  An example of displaying the geometry and tracks using OGL is given in the 
  macro vis.mac.  

  \section exgps_s5 HISTOGRAMS

  This example implements an histo manager which creates histograms and
  ntuples using Geant4 analysis tools.
     
  The output file contains 6 histograms and one ntuple:

  histo1D 1: energy spectrum.
  histo1D 2: vertex: radial distribution dN/dv.
  histo1D 3: angular distribution: cos(theta).
  histo1D 4: angular distribution: phi.        
  histo2D 1: vertex position in the X-Y plane.
  histo2D 2: vertex position in the X-Z plane.
  histo2D 3: vertex position in the Y-Z plane.
  histo2D 4: angular distribution: phi-cos(theta).
  histo2D 5: angular distribution: of phi-theta.
 
  In the ntuple the following data are recorded for each incident particle:  

  Particle ID
  Incident Position (x,y,z);
  Incident Angle (theta,phi);
  Particle weight;
	
  The histograms are managed by G4AnalysisManager class and its Messenger. 
  The histos can be individually activated with the command :
\verbatim  
  /analysis/h1/set id nbBins  valMin valMax unit
\endverbatim   
  where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
   
  One can control the name of the histograms file with the command:
\verbatim   
  /analysis/setFileName  name  (default exgps)
\endverbatim 
   
  It is possible to choose the format of the histogram file : root (default),
  xml, csv, by using namespace in HistoManager.hh 
	

  \section exgps_s6 GETTING STARTED
 
  - execute exgps in 'batch' mode from macro files
\verbatim  
	% exgps   exgps.in
\endverbatim
  		
  - execute exgps in 'interactive mode' with visualization
\verbatim  
	% exgps
	....
	Idle> type your commands
	....
	Idle> exit
\endverbatim
 
 \section exgps_s7  FURTHER EXAMPLES of MACRO FILES

 There are a number of mac files in the ./macros subdirectory, to show the 
 various features of GPS. 
 Please see macros/README file for further informations.

*/
