electromagnetic/TestEm4/README.md

0001 \page ExampleTestEm4 Example TestEm4
0002
0003  Plot energy deposited by 9 MeV photon beam in an homogeneous medium.
0004
0005 ## GEOMETRY DEFINITION
0006
0007  It is a cylinder of 5 cm radius filled with C6F6.
0008
0009 ## PHYSICS LIST
0010
0011  The particle list contains only gamma, electron,positron.
0012  The physics list contains the 'standard' electromagnetic processes.
0013
0014 ## AN EVENT : THE PRIMARY GENERATOR
0015
0016  The primary kinematic is a single 9 MeV gamma randomly shooted at the
0017  middle of the cylinder.
0018
0019 ## VISUALIZATION
0020
0021  The Visualization Manager is set in the main().
0022  The initialisation of the drawing is done via the commands
0023  `/vis/..` in the macro vis.mac. This macro is
0024  automatically read from the main in case of interactive running mode.
0025
0026  The detector has a default view which is a transversal view of the
0027  cylinder.
0028
0029  The tracks are drawn at the end of event, and erased at the end of run.
0030  Optionaly one can choose to draw all particles, only the charged one,
0031  or none. This command is defined in EventActionMessenger class.
0032
0033 ## PHYSICS SURVEY
0034
0035  The energy deposited in C6F6 is histogramed.
0036
0037 ## HOW TO START ?
0038
0039  - Execute TestEm4 in 'batch' mode from macro files
0040 ```
0041 % ./TestEm4   TestEm4.in
0042 ```
0043
0044  - Execute TestEm4 in 'interactive mode' with visualization
0045 ```
0046 % ./TestEm4
0047 ....
0048 Idle> type your commands
0049 ....
0050 Idle> exit
0051 ```
0052
0053 macro verbose.mac illustrate capability of verbosity
0054
0055 ## USING HISTOGRAMS
0056
0057  The format of the histogram file can be : root (default),
0058  xml, csv, by changing the default file type in RunAction.cc
0059
0060 ## RANDOM NUMBERS HANDLING
0061
0062    CLHEP provides several random number engines. In this example the Ranecu
0063    engine is choosen at beginning of the main (TestEm4.cc).
0064
0065    By default, G4RunManager does not save the rndm seed.
0066    To do so the user must set in BeginOfRunAction:
0067    G4RunManager::GetRunManager()->SetRandomNumberStore(true);
0068
0069    Then the rndm seed is systematically saved at beginning of run
0070    (currentRun.rndm) and beginning of event (currentEvent.rndm)
0071    Therefore, in case of abnormal end, the seed of the last event processed
0072    is available in currentEvent.rndm
0073
0074    Even in case of normal run processing, the user may wish to preserve the
0075    rndm seed of selected events. At any time in the event, put the
0076    following statement:
0077 ```cpp
0078 if (condition) G4RunManager::GetRunManager()->rndmSaveThisEvent();
0079 ```
0080    currentEvent.rndm will be copied to runXXevntYY.rndm
0081    (see SteppingAction::UserSteppingAction() )
0082
0083    To restart a run from a given rndm seed, use the UI command :
0084 ```
0085 /random/resetEngineFrom  fileName
0086 ```
0087
0088    The macro rndmSeed.mac shows how to save and reset the random number
0089    seed between runs, from UI commands.
0090
0091