geant4

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     =========================================================
     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                            TestEm11
                            --------

    How to plot a depth dose profile in a rectangular box.    

	
 1- GEOMETRY DEFINITION
 
 The geometry consists of a stack of one or several blocks of homogenous
 material, called absorbers.
 Optionally, each absorber can be divided in thinner layers (replica)
     	
 A minimum of 5 parameters define the geometry :
    - the number of absorbers (NbOfAbsor)	
    - the material of each absorber,
    - the thickness of each absorber,
    - the tranverse dimension of the stack (sizeYZ),
    - the number of divisions of each absorber (NbOfDivisions)
	 	
 In addition a transverse uniform magnetic field can be applied.
     eg: /globalField/setValue 0 0 5 tesla
 	
 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 are based on modular design. Several modules are instantiated:
 1. Transportation
 2. EM physics
 3. Decays
 4. StepMax - for step limitation

 The following options for EM physics using builders from physics_lists
 sub-package are available:
 - "emstandard_opt0" recommended standard EM physics for LHC
 - "emstandard_opt1" best CPU performance standard physics for LHC
 - "emstandard_opt2" similar fast simulation
 - "emstandard_opt3" best standard EM options - analog to "local" above
 - "emstandard_opt4" best current advanced EM options standard + lowenergy
 - "emstandardWVI" standard EM physics and WentzelVI multiple scattering
 - "emstandardSS"  standard EM physics and single scattering model
 - "emstandardGS"  standard EM physics and Goudsmit-Saunderson multiple scatt.
 - "emlivermore"  low-energy EM physics using Livermore data
 - "empenelope"   low-energy EM physics implementing Penelope models
 - "emlowenergy"  low-energy EM physics implementing experimental
                  low-energy models
 - "emstandardMP" standard EM physics where for e- a new model
                  G4DiscreteScatteringModel is applied; for this model 
                  a data set G4GBFPDATA should be requested from EM group

 A local builder, PhysListEmStandard "local" (similar to opt3) is also
 available.
      
 Physics lists and options can be (re)set with UI commands
    
 3- ACTION INITIALIZATION

 A newly introduced class, ActionInitialization, instantiates and registers 
 to Geant4 kernel all user action classes.

 While in sequential mode the action classes are instantiated just once,
 via invoking the method:
    ActionInitialization::Build() 
 in multi-threading mode the same method is invoked for each thread worker
 and so all user action classes are defined thread-local.

 A run action class (if present) has to be instantiated both thread-local 
 and global, which is why its instance has to be created also in the method
    ActionInitialization::BuildForMaster() 
 which is invoked only in multi-threading mode.
  	 
 4- 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 G4ParticleGun 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 class.
	 	
 A RUN is a set of events.
 	
 5- 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.
 Optionally one can choose to draw all particles, only the charged one,
 or none. This command is defined in EventActionMessenger class.
 	
 6- HOW TO START ?
 
 - Execute TestEm11 in 'batch' mode from macro files
 	% TestEm11   run01.mac
 		
 - Execute TestEm11 in 'interactive mode' with visualization
 	% TestEm11
 	....
 	Idle> type your commands
 	....
 	Idle> exit

  Macros provided in this example:
  - alpha.mac: alpha (400 MeV) on water
  - ionC12.mac: ion C12 (2.4 GeV) on water
  - multiLayers.mac: gamma (6 MeV) on multi layers
  - radioactive.mac: radioactive ion on multi layers
  - range.mac: compute csda range of primary particle
  - run01.mac: e- (500 keV) on silicon. Step max from histo 1
  - run02.mac: e- (500 keV) on silicon. Step max from geometry
  - sandia.mac: to compare with Sandia data
  - water.mac: e- (4 MeV) on water. No constraint on tracking step  

  Macros to be run interactively:
  - vis.mac: To activate visualization
  	
 7- TRACKING and STEP MAX
 
 TestEm11 computes the distribution of energy deposited along the trajectory of 
 the incident particle : the so-called longitudinal energy profile,
 or depth dose distribution.
 The energy deposited (edep) is randomly distribued along the step (see
 SteppingAction).
     
 In order to control the accuracy of the deposition, the maximum  step size 
 of charged particles is computed automatically from the binning of 
 histograms 1 and 8 (see RunAction).
     
 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.
     
 StepMax is evaluated at RunAction::BeginOfRun(),
 and passed to the StepMax process. 
 A boolean UI command allows to deactivate this mechanism.
 Another UI command allows to define directly a stepMax value.
     	
 8- HISTOGRAMS
 
   TestEm11 has several predefined 1D histograms : 
  
      1 : longitudinal energy profile (in MeV/mm and per event)
      2 : total energy deposited in all absorbers
      3 : total track length of the primary track
      4 : step size of the primary track      
      5 : projected range of the primary track
      6 : total track length of charged secondary tracks
      7 : step size of charged secondary tracks      
      8 : longitudinal energy profile (in MeV.cm2/g), as a function of x/r0
          where r0 is the range of the primary particle 

      11 : energy deposited in absorber 1
      12 : energy deposited in absorber 2
      ...etc........

   The histograms are managed by G4Analysis classes. 
   The histos can be individually activated with the command :
   /analysis/h1/set 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:
   /analysis/setFileName  name  (default testem11)
   
   It is possible to choose the format of the histogram file : root (default),
   hbook, xml, csv, by using namespace in HistoManager.hh    
   
   It is also possible to print selected histograms on an ascii file:
   /analysis/h1/setAscii id
   All selected histos will be written on a file name.ascii  (default testem11)