$Id: README,v 1.5 2010/09/08 11:22:01 vnivanch Exp $
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     =========================================================
     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
     =========================================================

                            TestEm8  
                            -------

    Example for investigation of ionisation in thin absorbers and gaseous
    detectors
	
 1- GEOMETRY DEFINITION
 
 	The target is a cilinder made of a given material placed inside
        cilindrical container, which is placed inside the world volume.
 	
 	Following parameters define the geometry:
 	- the material of the target,
	- the thickness of the target,
 	- the radius of the target, 
 	- the material of the container,
	- the thickness of the container,
 	- the material of the world.
 	
        The list of materials used in gaseous detectors are built inside
        the DetectorConstruction class, also NIST materials are availabe. 
 	The default geometry is provided but all parameters can be changed via
 	UI commands defined in the DetectorMessenger class, for example,

    /testem/setGasMat      XeCH4C3H8
    /testem/setWindowMat   G4_MYLAR
    /testem/setWorldMat    G4_AIR
    /testem/setGasThick    10 cm
    /testem/setGasRad      20 cm
    /testem/setWindowThick 50 um

 	
 2- 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 can be set via the G4 build-in commands of ParticleGun 
 	A RUN is a set of events.
 	
 3- DETECTOR RESPONSE

        The TargetSD class sending information about each step inside the target
        to the HistoManager class scoring of energy deposition in the detector.
        Additionally at each step of a particle inside the target the number of 
        ionisation clusters is sampled using G4ElectronIonPair helper class. The
        parameter of transformation of energy into ionisation clusters can be
        set via UI command:

      /testem/setPairEnergy 19 eV

 				
 4- PHYSICS 
 
 	The particle's type and the physic processes which will be available
 	in this example are set in PhysicsList class, which uses Geant4
        EM physics constructors providing in the physics_list library.

 	The  messenger classes introduce interactive commands. In particular,
        PAI ionisation model can be added using G4EmConfurator helper class,
        which is invokated by the UI command

      /testem/phys/addPhysics pai

 5- HOW TO START ?
 
 	- compile and link to generate an executable
 		% cd TestEm8
 		% gmake
 		
 	- execute TestEm8 in 'batch' mode from macro files e.g.
 		% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8  TestEm8.in
		
 	- execute TestEm8 in 'interactive' mode with visualization e.g.
 		% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8
		....
		Idle> type your commands
		....