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0001 -------------------------------------------------------------------
0002
0003 =========================================================
0004 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0005 =========================================================
0006
0007 TestEm8
0008 -------
0009
0010 Example for investigation of ionisation in thin absorbers and gaseous
0011 detectors
0012
0013 1- GEOMETRY DEFINITION
0014
0015 The target is a cylinder made of a given material placed inside
0016 cylindrical container, which is placed inside the world volume.
0017
0018 Following parameters define the geometry:
0019 - the material of the target,
0020 - the thickness of the target,
0021 - the radius of the target,
0022 - the material of the container,
0023 - the thickness of the container,
0024 - the material of the world.
0025
0026 The list of materials used in gaseous detectors are built inside
0027 the DetectorConstruction class, also NIST materials are available.
0028 The default geometry is provided but all parameters can be changed via
0029 UI commands defined in the DetectorMessenger class, for example,
0030
0031 /testem/setGasMat XeCH4C3H8
0032 /testem/setWindowMat G4_MYLAR
0033 /testem/setWorldMat G4_AIR
0034 /testem/setGasThick 10 cm
0035 /testem/setGasRad 20 cm
0036 /testem/setWindowThick 50 um
0037
0038 2- AN EVENT : THE PRIMARY GENERATOR
0039
0040 The primary kinematic consists of a single particle which hits the
0041 absorber perpendicular to the input face. The type of the particle
0042 and its energy can be set via the G4 build-in commands of G4ParticleGun.
0043 A RUN is a set of events.
0044
0045 3- DETECTOR RESPONSE
0046
0047 The TargetSD class sending information about each step inside the target
0048 to the HistoManager class scoring of energy deposition in the detector.
0049 Additionally at each step of a particle inside the target the number of
0050 ionisation clusters is sampled using G4ElectronIonPair helper class. The
0051 parameter of transformation of energy into ionisation clusters can be
0052 set via UI command:
0053
0054 /testem/setPairEnergy 19 eV
0055
0056 4- PHYSICS
0057
0058 The particle's type and the physics processes which will be available
0059 in this example are set in PhysicsList class, which uses Geant4
0060 EM physics constructors provided in the physics_list library.
0061
0062 The messenger classes introduce interactive commands. In particular,
0063 PAI ionisation model can be added using G4EmConfigurator helper class,
0064 which is invoked by one following UI commands:
0065
0066 /testem/phys/addPhysics pai
0067 /testem/phys/addPhysics pai_photon
0068 /process/em/AddPAIRegion all GasDetector pai
0069 /process/em/AddPAIRegion all GasDetector pai_photon
0070
0071 Cuts for all setup and/or for sensitive volume may changed via commands:
0072
0073 /run/setCut 0.5 mm
0074 /run/setCutForRegion GasDetector 1.8 mm
0075
0076 5- HOW TO START ?
0077
0078 Execute TestEm8 in 'batch' mode from macro files e.g.
0079 % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8 TestEm8.in N
0080 here N means number of threads in multi-threaded mode, by
0081 default 2 threads are used
0082
0083 - execute TestEm8 in 'interactive' mode with visualization e.g.
0084 % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm8
0085 ....
0086 Idle> type your commands
0087 ....
