$Id: README,v 1.28 2010/06/06 04:25:24 perl Exp $
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     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                            TestEm1
                            -------
  How to count processes.
  How to activate/inactivate processes.
  How to survey the tracking, in perticular the range of charged particles.
  How to define a maximum step size.
	
 1 - GEOMETRY DEFINITION
 
  It is a simple box which represente an 'semi infinite' homogeneous medium.
 	
  Two parameters define the geometry :
   - the material of the box,
   - the full size of the box.
	 	
  In addition a transverse uniform magnetic field can be applied.
 	
  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
 
  Physics lists can be local (eg. in this example) or from G4 kernel
  physics_lists subdirectory.
     
  Local physics list:	 
   - "local"	  standard EM physics with current 'best' options setting.
                  these options are explicited in PhysListEmStandard
    
  From geant4/source/physics_lists/builders:	 
   - "emstandard_opt0" recommended standard EM physics for LHC
   - "emstandard_opt1" best CPU performance standard physics for LHC
   - "emstandard_opt2"     
   - "emstandard_opt3" best current advanced EM options. 
                       analog to "local" above
             
  Physics lists and options can be (re)set with UI commands
    
  Please, notice that options set through G4EmProcessOPtions are global, eg
  for all particle types. In G4 builders (geant4/source/physics_lists/builders)
  it is shown how to set options per particle type. 
 		
  Few commands have been added to PhysicsList, in order to set the production 
  threshold for secondaries for gamma and e-/e+.
 	 
 3 - AN EVENT : THE PRIMARY GENERATOR
 
  The primary kinematic consists of a single particle starting at the left face 
  of the box. 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 ParticleGun class (see the macros provided with this example).
	
  In addition one can choose randomly the impact point of the incident particle.
  The corresponding interactive command is built in PrimaryGeneratorMessenger.	
 				
 4 - VISUALIZATION
 
  The Visualization Manager is set in the main().
  The initialisation of the drawing is done via the commands /vis/... in the 
  macro vis.mac. To get visualisation:
	> /control/execute vis.mac
 	
  The detector has a default view which is a longitudinal view of the box.
 	
  The tracks are drawn at the end of event, and erased at the end of run.
 	
 5 - PHYSICS SURVEY
 
  The particle's type and the physic processes which will be available in this 
  example are set in PhysicsList class.
 	
  A set of macros defining various run conditions are provided. The processes 
  are actived/inactived together with differents cuts, in order to survey the 
  processes one by one.

  The number of produced secondaries are counted, the number of steps, and the 
  number of process calls responsible of the step.
 	
 6 - HOW TO START ?
 
  - compile and link to generate an executable
	% cd geant4/examples/extended/electromagnetic/TestEm1
	% gmake
 		
  - execute TestEm1 in 'batch' mode from macro files
	% TestEm1   run10.mac
 		
  - execute TestEm1 in 'interactive mode' with visualization
	% TestEm1
	....
	Idle> type your commands
	....
	Idle> exit
		
 7 - TRACKING : StepMax
 
  In order to control the accuracy of the deposition, the user can limit
  'by hand' the maximum  step size of charged particles.
  As an example, this limitation is implemented as a 'full' process :
  see StepMax class and its Messenger. The 'StepMax process' is registered
  in the Physics List. 
  	
 8 - HISTOGRAMS
 
  Testem1 produces several histo which are saved as testem1.root by default.
  Content of these histo:  
      1 : track length of primary particle
      2 : number of steps primary particle
      3 : step size of primary particle
      
   The histograms are managed by the HistoManager class and its Messenger. 
   The histos can be individually activated with the command :
   /testem/histo/setHisto id nbBins  valMin valMax unit 
   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:
   /testem/histo/setFileName  name  (default testem1)
   
   It is possible to choose the format of the histogram file (hbook, root, XML)
   with the command /testem/histo/setFileType (root by default)
   
   It is also possible to print selected histograms on an ascii file:
   /testem/histo/printHisto id
   All selected histos will be written on a file name.ascii  (default testem1) 

  Note that, by default, histograms are disabled. To activate them, uncomment
  the flag G4ANALYSIS_USE in GNUmakefile.
 
  Before compilation of the example it is optimal to clean up old files:
  	gmake histclean
  	gmake 

 9 - USING HISTOGRAMS

  To use histograms, at least one of the AIDA implementations should be 
  available. See the file InstallAida.txt