geant4

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     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                            field02
                            -------

    Test for investigation of tracking in electric field
    and field dependent electromagnetic processes.

 1- FIELD DEFINITION
        The field is a constant electric field.

        Technical note: in order to use any electric field, it is
 	necessary to  create the objects for its equation of motion,
	the stepper and driver for the integration, and the
	chord finder.

        The class that does these is G4FieldBuilder. Its object
        is created in the F02DetectorConstruction constructor and 
        its instantiation adds the /field UI commands that allow user
        to choose the field configuration parameters.

        The electric field (G4UniformElectricField) is then created in 
        F02DetectorConstruction::ConstructSDanField() and passed to
        G4FieldBuilder, that constructs all necessary objects according
        to the user defined (or default) configuration parameters.

 1- GEOMETRY DEFINITION

 	The "Absorber" is a solid 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).

        The volume "World" contains the "Absorber".
        In this test the parameters of the "World" can be changed , too.

 	In addition a transverse uniform electric field can be applied.

 	The default geometry is constructed in F02DetectorConstruction class,
 	but all the parameters can be changed via
 	the commands defined in the F02DetectorMessenger class.

 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 are set in the F02PrimaryGeneratorAction class, and can
 	be changed via the G4 build-in commands of G4ParticleGun class (see
 	the macros provided with this example).

    It is also possible to change the position of the primary particle vertex
    or activate its randomization via the commands defined in  the
    F01PrimaryGeneratorMessenger class.

 	A RUN is a set of events.

 3- DETECTOR RESPONSE


 	A HIT is a record, event per event , of all the
 	informations needed to simulate and analyse the detector response.

 	In this example a F02CalorHit is defined as a set of 2 informations:
 	- the total energy deposit in the absorber,
 	- the total tracklength of all charged particles in the absorber,

 	Therefore  the absorber is declared
 	'sensitive detector' (SD), see F02CalorimeterSD, which means they can contribute to the hit.

 4- PHYSICS LIST

     The particle's type and the physic processes which will be available
     in this example are set in the FTFP_BERT physics list. This physics list
     requires data files for electromagnetic and hadronic processes.
     See more on installation of the datasets in Geant4 Installation Guide,

 5- HOW TO START ?

 	- Execute field02 in 'batch' mode from macro file e.g.
 		% ./field02 field02.in

 	- Execute field02 in 'interactive' mode with visualization e.g.
 		% ./field02
		....
		Idle> /run/beamOn 1
		....