Gabriele Cosmo
58 lines
2.4 KiB
Plaintext
58 lines
2.4 KiB
Plaintext
$Id: README,v 1.3 2002/07/02 18:35:01 asaim Exp $
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-------------------------------------------------------------------
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=========================================================
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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=========================================================
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ExampleN01
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ExampleN01 is the simplest example in this novice level examples. It has
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a tracker tube and a sandwitch calorimeter made of boxes. It shoots a
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geantino (pseudo-particle which has no "real" physics interaction) per
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one event. This example demonstrates how the basic GEANT4 framework works.
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1. Detector description
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The detector is defined in ExN01DetectorConstruction.cc. Argon gas,
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aluminum and lead are defined first, where all of them are single element
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materials. Though materials are assigned for each volume, they will not
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affect the trajectory of a geantino.
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The experimental hall, which is the world volume, is made of argon gas
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and it is a box. The tracker tube made of argon gas is placed at
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(-1m,0m,0m) respect to the origin of the world volume. The calorimeter
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block made of lead and it has 19 layers of aluminum plates inside.
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2. Physics processes
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ExN01PhysicsList.cc defines only a geantino and a transportation
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process. Though cutoff will not be applied onto geantino, a dummy
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value must be set.
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3. Event generation
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G4ParticleGun is instanciated in the constructor of
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ExN01PrimaryGeneratorAction class. At the every event, the public
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method GeneratePrimaries(G4Event*) is invoked. In this method,
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G4ParticleGun is accessed to generate a primary particle (geantino).
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Please note that the direction of the primary particle is set
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just before shooting, i.e. GeneratePrimaryVertex() method invokation.
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G4ParticleGun class itself does not have any capability of randomizing
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the energy nor the momentum of the primary particle. Therefore the user
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should implement randomizing code in the GeneratePrimaries() method.
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4. main()
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exampleN01.cc has the main() method. In the main() method, three
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mandatory user classes described above are constructed and set to
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the G4RunManager object. Then, the "Initialize()" method of G4RunManager
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is invoked.
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Some UI commands for setting verbosity are applied via hardly coded
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"ApplyCommand()" method of G4UImanager class.
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The "BeamOn()" method triggers the event loop. The argument of this
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method is the number of event in the run.
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