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0001 -------------------------------------------------------------------
0002
0003 =========================================================
0004 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0005 =========================================================
0006
0007 TestEm4
0008 -------
0009
0010 Plot energy deposited by 9 MeV photon beam in an homogeneous medium.
0011
0012 1- GEOMETRY DEFINITION
0013
0014 It is a cylinder of 5 cm radius filled with C6F6.
0015
0016 2- PHYSICS LIST
0017
0018 The particle list contains only gamma, electron,positron.
0019 The physics list contains the 'standard' electromagnetic processes.
0020
0021 3- AN EVENT : THE PRIMARY GENERATOR
0022
0023 The primary kinematic is a single 9 MeV gamma randomly shooted at the
0024 middle of the cylinder.
0025
0026 4- VISUALIZATION
0027
0028 The Visualization Manager is set in the main().
0029 The initialisation of the drawing is done via the commands
0030 /vis/.. in the macro vis.mac. This macro is
0031 automatically read from the main in case of interactive running mode.
0032
0033 The detector has a default view which is a transversal view of the
0034 cylinder.
0035
0036 The tracks are drawn at the end of event, and erased at the end of run.
0037 Optionaly one can choose to draw all particles, only the charged one,
0038 or none. This command is defined in EventActionMessenger class.
0039
0040 5- PHYSICS SURVEY
0041
0042 The energy deposited in C6F6 is histogramed.
0043
0044 6- HOW TO START ?
0045
0046 - execute TestEm4 in 'batch' mode from macro files
0047 % TestEm4 TestEm4.in
0048
0049 - execute TestEm4 in 'interactive mode' with visualization
0050 % TestEm4
0051 ....
0052 Idle> type your commands
0053 ....
0054 Idle> exit
0055
0056 macro verbose.mac illustrate capability of verbosity
0057
0058 7- USING HISTOGRAMS
0059
0060 The format of the histogram file can be : root (default),
0061 xml, csv, by selecting g4nnn.hh in RunAction.hh
0062
0063 8- RANDOM NUMBERS HANDLING
0064
0065 CLHEP provides several random number engines. In this example the Ranecu
0066 engine is choosen at beginning of the main (TestEm4.cc).
0067
0068 By default, G4RunManager does not save the rndm seed.
0069 To do so the user must set in BeginOfRunAction:
0070 G4RunManager::GetRunManager()->SetRandomNumberStore(true);
0071
0072 Then the rndm seed is systematically saved at beginning of run
0073 (currentRun.rndm) and beginning of event (currentEvent.rndm)
0074 Therefore, in case of abnormal end, the seed of the last event processed
0075 is available in currentEvent.rndm
0076
0077 Even in case of normal run processing, the user may wish to preserve the
0078 rndm seed of selected events. At any time in the event, put the
0079 following statement:
0080 if (condition) G4RunManager::GetRunManager()->rndmSaveThisEvent();
0081 currentEvent.rndm will be copied to runXXevntYY.rndm
0082 (see SteppingAction::UserSteppingAction() )
0083
0084 To restart a run from a given rndm seed, use the UI command :
0085 /random/resetEngineFrom fileName
0086
0087 The macro rndmSeed.mac shows how to save and reset the random number
0088 seed between runs, from UI commands.
