$Id: README 66241 2012-12-13 18:34:42Z gunter $
-----------------------------------------------------

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

                            TestEm5   
                            -------
 How to study the transmission, absorption and reflexion of particles through
 a single, thin or thick, layer of material.
 In particular, the effects of the multiple scattering can be ploted.  
	
 1- GEOMETRY DEFINITION
 
 The "absorber" is a box made of a given material.                
 	
 Three parameters define the absorber :
 - the material of the absorber,
 - the thickness of an absorber,
 - the transverse size of the absorber (the input face is a square). 
    
 A volume "World" contains the "absorber". 

 In addition a transverse uniform magnetic field can be applied.
 	
 The default geometry is constructed in DetectorConstruction class, but all the
 parameters can be changed via commands defined in the DetectorMessenger class.
 The parameters of the "World" can be changed, too. However, if World material
 is not set to vacuum, the plots 10->43 below may be not pertinent.
 
 2- PHYSICS LIST
 
 Physics lists can be local (eg. in this example) or from G4 kernel
 physics_lists subdirectory.
     
 Local physics lists:	 
 - "local"	standard EM physics with current 'best' options setting.
                these options are explicited in PhysListEmStandard
 - "standardSS" standard EM physics with single Coulomb scattering 
                instead of multiple scattering			
    
 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 standard EM options - analog to "local" above
 - "emstandard_opt4" best current advanced EM options standard + lowenergy   
 - "emlivermore"  low-energy EM physics using Livermore data
 - "empenelope"   low-energy EM physics implementing Penelope models
           
 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, it is shown how to set options per
 particle type.

         	
 3- AN EVENT : THE PRIMARY GENERATOR
 
 The primary kinematic consists of a single particle which hits the absorber 
 perpendicular to the input face. 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 interactive command is built in PrimaryGeneratorMessenger class.
 
 4- VISUALIZATION
 
 The Visualization Manager is set in the main().
 The initialisation of the drawing is done via the commands in vis.mac
 In interactive session:
 PreInit or Idle > /control/execute vis.mac
 	
 The example has a default view which is a longitudinal view of the detector.
 	
 The tracks are drawn at the end of event, and erased at the end of run.
 Optionaly one can choose to draw all particles, only the charged, or none.
 This command is defined in EventActionMessenger class.
 
 5- TRACKING
 
 During the tracking, one can keep or not the secondaries : see StackingAction
 class and its Messenger (StackingMessenger).
 One can also limit 'by hand' the step lenght of the particle. 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. 
  	
 6- DETECTOR RESPONSE
  	
 At the end of a run, from the histogram(s), one can study different
 physics quantities such as :
 - energy deposit in the absorber,
 - energy spectrum of secondaries at creation, 
 - energy spectrum and angle distribution of particles at exit,
 - transmission and backscattering coefficients,
 -  ...
 
 7- List of the built-in histograms
 ----------------------------------
        
 The test contains more than 20 built-in 1D histograms, which are managed by
 G4AnalysisManager class and its Messenger. 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..)
 (see the macros xxxx.mac).
 
	1	"energy deposit in absorber"
	2	"energy of charged secondaries at creation"
	3	"energy of neutral secondaries at creation"	
	4	"energy of charged at creation (log10(Ekin))"
	5	"energy of neutral at creation (log10(Ekin))"	
	6       "x_vertex of charged secondaries (all)"
	7       "x_vertex of charged secondaries (not absorbed)"
	10	"(transmit, charged) : kinetic energy at exit of world"
        11	"(transmit, charged) : ener fluence: dE(MeV)/dOmega"	
	12	"(transmit, charged) : space angle dN/dOmega"
	13	"(transmit, charged) : projected angle at exit of world"
	14	"(transmit, charged) : projected position at exit of world"
	15	"(transmit, charged) : radius at exit of world"	
	20	"(transmit, neutral) : kinetic energy at exit of world"
	21	"(transmit, neutral) : ener fluence: dE(MeV)/dOmega"	
	22	"(transmit, neutral) : space angle dN/dOmega"
	23	"(transmit, neutral) : projected angle at exit of world"
	30	"(reflect , charged) : kinetic energy at exit of world"
	31	"(reflect , charged) : ener fluence: dE(MeV)/dOmega"	
	32	"(reflect , charged) : space angle dN/dOmega"
	33	"(reflect , charged) : projected angle at exit of world"
	40	"(reflect , neutral) : kinetic energy at exit of world"
	41	"(reflect , neutral) : ener fluence: dE(MeV)/dOmega"	
	42	"(reflect , neutral) : space angle dN/dOmega"
	43	"(reflect , neutral) : projected angle at exit of world"

 The histograms can be viewed using ROOT or PAW.
 
 One can control the name of the histograms file with the command:
 /analysis/setFileName  name  (default testem5)
   
 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 testem5) 
    
 Using hbook format
 ------------------
 
 Need a special treatement : the Cern Library must be installed and the
 environment variable CERNLIB correctly set. Then, *before* compiling,
 activate G4_USE_HBOOK in GNUmakefile and g4hbook.hh in HistoManager.hh
 				
 8- GEANT4/GEANT3/DATA COMPARISON

 A Geant4/Geant3/exp. data comparison is given here for a few cases.
 These cases can be classified as follow:
 - e-/e+ incident particles versus protons and others. 
 - 3 energy regimes: low: < 1MeV; medium: 1MeV -> few 10MeV; high: > 100MeV
 
 We indicate here the corresponding macros.
 
 	      |	low energy   |	medium energy	|  high energy
	--------------------------------------------------------
	      | acosta.mac   |                  |
	e-+   |	berger.mac   |	hanson.mac      |
	      |	hunger.mac   |	kulchi.mac      |
	      | tavola.mac   |			|
	--------------------------------------------------------
	others|	bichsel.mac  | 	vincour.mac	|  shen1.mac shen2.mac
	      | 	     |	gottsch.mac	|  tramu.mac
	--------------------------------------------------------

 The relevant part of the GEANT3 code is in the subdirectory geant3 together 
 with the xxxx.dat input files.
	
 9- HOW TO START ?
 
 - execute TestEm5 in 'batch' mode from macro files e.g.
 	% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5   myMacro.mac
		
 - execute TestEm5 in 'interactive' mode with visualization e.g.
 	% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5
	Then type your commands, for instance :
	Idle> control/execute vis.mac
	Idle> run/beamOn 5
	....