Introduction to Geant4 Lectures by Andrea dell'Acqua (CERN) From the Ann Arbor Workshop on Geant4 26 February to 2 March, 2001.

Exercise N02

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This exercise comes from Lecture 3, Getting Started, and starts on slide number 16.
 

Steps ExN02

Very basic example, depicting some kind of fixed target experimental setup.

1. Change directory to geant4/N02 which contains:
•  a GNUmakefile
very basic, essentially defining the name of the executable and running binmake.gmk
• the main program (exampleN02.cc)
• a macro file (prerun.g4mac)
• an include directory
class header files
• a src directory
implementation of all methods

2. Create the executable with gmake
3. Run the executable by typing
$G4WORKDIR/bin/$G4SYSTEM/exampleN02
4. A macro file should initialize graphics for you.  This is run automatically.
5. Draw the experimental setup and get the GUI by
/vis/show/view
6. Tell the tracking of storing all track segments by
/tracking/storeTrajectory 1
7. And run one event
/run/beamOn 1

 
8. You can change the beam condition by using the /gun commands
/gun/List    //to have a list of all possible particles
/gun/particle e+
/gun/energy 10 GeV
/gun/position 0 10 30 cm
/gun/direction .3 .3 .1
9. Have a look at the online help to see what you can do...

Definitions

• The G4RunManager is the only manager class in the Geant4 kernel, the root class of the Geant4 hierarchy.  It is used in the main program to specify:
• How the detector geometry should be built
• Which physics processes are preferred
• How the primary particles in an event should be produced
• Additional requests during the simulation procedures

Helpful Links

• Check out slide 2 for reminders about naming conventions in Geant4.
• Slide 5 shows how the G4RunManager controls the main flow of the program.
• For optional user action classes, look at slide 9.
• For an example of main(), start by looking at slide 10.

Checklist

• Remember that Geant4 does not contain a main() file. You must supply your own in order to build the simulation program.
• Make sure that all three user defined classes are implemented.  Start with slide 8 if you think that one of the following might have been forgotten.
• setting up the geometry
• event kinematics
• physics processes

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