$Id: README,v 1.3 2001/03/30 12:41:27 gcosmo Exp $
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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TestEm1
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This example has been setup to test individualy the electromagnetic
processes.
1- GEOMETRY DEFINITION
It is a simple box which represente an '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
The particle list is the one of novice/exampleN03.
The physics list contains the 'standard' electromagnetic processes,
and decay.
Few commands have been added to PhysicsList, in order to set the
production threshold for secondaries either in range for gamma,
e-/e+, proton or directly in energy for all charged.
3- AN EVENT : THE PRIMARY GENERATOR
The primary kinematic consists of a single particle starting at the
middle 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).
A RUN is a set of events.
4- VISUALIZATION
The Visualization Manager is set in the main().
The initialisation of the drawing is done via the command
/vis~/create_view in the macro init.mac. This macro is
automatically read from the main in case of interactive running mode.
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.
Optionaly one can choose to draw all particles, only the charged one,
or none. This command is defined in EventActionMessenger class.
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- HISTOGRAMS
Testem1 produces several histo which are saved as testem1.paw
Content of these histo:
1 : track length of a charged particle
2 : number of steps per track (charged particle)
3 : step length (charged particle)
Note that, histograms are disabled via the flag G4NOHIST in the GNUmakefile.
Currently, histograms in this example are implemented through the obsolete
CLHEP/Hist package, which is no longer supported. The implementation will
be replaced by direct call to the "analysis" module in a near future.
Gabriele Cosmo