Gabriele Cosmo
88 lines
3.1 KiB
Plaintext
88 lines
3.1 KiB
Plaintext
-------------------------------------------------------------------
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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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TestEm8
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-------
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Example for investigation of ionisation in thin absorbers and gaseous
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detectors
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1- GEOMETRY DEFINITION
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The target is a cylinder made of a given material placed inside
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cylindrical container, which is placed inside the world volume.
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Following parameters define the geometry:
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- the material of the target,
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- the thickness of the target,
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- the radius of the target,
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- the material of the container,
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- the thickness of the container,
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- the material of the world.
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The list of materials used in gaseous detectors are built inside
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the DetectorConstruction class, also NIST materials are available.
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The default geometry is provided but all parameters can be changed via
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UI commands defined in the DetectorMessenger class, for example,
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/testem/setGasMat XeCH4C3H8
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/testem/setWindowMat G4_MYLAR
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/testem/setWorldMat G4_AIR
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/testem/setGasThick 10 cm
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/testem/setGasRad 20 cm
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/testem/setWindowThick 50 um
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2- AN EVENT : THE PRIMARY GENERATOR
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The primary kinematic consists of a single particle which hits the
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absorber perpendicular to the input face. The type of the particle
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and its energy can be set via the G4 build-in commands of G4ParticleGun.
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A RUN is a set of events.
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3- DETECTOR RESPONSE
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The TargetSD class sending information about each step inside the target
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to the HistoManager class scoring of energy deposition in the detector.
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Additionally at each step of a particle inside the target the number of
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ionisation clusters is sampled using G4ElectronIonPair helper class. The
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parameter of transformation of energy into ionisation clusters can be
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set via UI command:
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/testem/setPairEnergy 19 eV
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4- PHYSICS
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The particle's type and the physics processes which will be available
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in this example are set in PhysicsList class, which uses Geant4
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EM physics constructors provided in the physics_list library.
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The messenger classes introduce interactive commands. In particular,
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PAI ionisation model can be added using G4EmConfigurator helper class,
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which is invoked by one following UI commands:
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/testem/phys/addPhysics pai
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/testem/phys/addPhysics pai_photon
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/process/em/AddPAIRegion all GasDetector pai
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/process/em/AddPAIRegion all GasDetector pai_photon
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Cuts for all setup and/or for sensitive volume may changed via commands:
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/run/setCut 0.5 mm
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/run/setCutForRegion GasDetector 1.8 mm
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5- HOW TO START ?
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Execute TestEm8 in 'batch' mode from macro files e.g.
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% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8 TestEm8.in N
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here N means number of threads in multi-threaded mode, by
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default 2 threads are used
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- execute TestEm8 in 'interactive' mode with visualization e.g.
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% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8
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....
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Idle> type your commands
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....
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