Gabriele Cosmo
129 lines
5.1 KiB
Plaintext
129 lines
5.1 KiB
Plaintext
$Id$
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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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Example B1
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-----------
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This example demonstrates a very simple application where an energy
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deposit is accounted in user actions and a dose in a selected volume
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is calculated.
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1- GEOMETRY DEFINITION
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The geometry is constructed in the B1DetectorConstruction class.
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The setup consists of a an envelope of box shape containing two
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volumes: a spherical cone and a trapezoid.
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In this example we use some common materials materials for medical
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applications. The envelope is made of water and the two inner volumes
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are made from tissue and bone materials.
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The materials are created with the help of the G4NistManager class,
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which allows to build a material from the NIST database using their
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names. All available materials can be found in the Geant4 User's Guide
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for Application Developers, Appendix 9: Geant4 Materials Database.
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2- PHYSICS LIST
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The particle's type and the physic processes which will be available
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in this example are set in the QGSP_BIC_EMY physics list. This physics
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list requires data files for low energy electromagnetic processes which
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path is defined via the G4LEDATA environment variable.
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In addition the build-in interactive command:
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/process/(in)activate processName
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allows to activate/inactivate the processes one by one.
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3- PRIMARY GENERATOR
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The primary generator is defined in the B1PrimaryGeneratorAction class.
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The default kinematic is a 6 MeV gamma, randomly distributed in front
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of the envelope across 80% of the (X,Y) envelope size.
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This default setting can be changed via the Geant4 built-in commands
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of the G4ParticleGun class.
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4- DETECTOR RESPONSE
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This example demonstrates a simple scoring implemented directly
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in the user action classes. Alternative ways of scoring via
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Geant4 classes can be found in the other examples.
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Here, the energy deposit in a selected volume is accumulated step by step
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in B1SteppingAction and the event energy deposit deposit is done event by
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event in B1EventAction. The dose is then computed in
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B1RunAction::EndOfRunAction() and and its value is printed on the screen.
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The following paragraphs are common to all basic examples
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A- VISUALISATION
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The visualization manager is set via the G4VisExecutive class
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in the main() function in exampleB1.cc.
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The initialisation of the drawing is done via a set of /vis/ commands
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in the macro vis.mac. This macro is automatically read from
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the main function when the example is used in interactive running mode.
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By default, vis.mac opens an OpenGL viewer.
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The user can switch to other graphics systems by commenting out this line
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and instead uncommenting one of the other /vis/open statements, such as
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HepRepFile or DAWNFILE (which produce files that can be viewed with the
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HepRApp and DAWN viewers, respectively).
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The DAWNFILE, HepRepFile drivers are always available
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(since they require no external libraries), but the OGL driver requires:
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1- the visualisation & interfaces categories have been compiled
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with the environment variable G4VIS_BUILD_OPENGLX_DRIVER.
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2- exampleB1.cc has been compiled with G4VIS_USE_OPENGLX.
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(This is best done through Configure or CMake.)
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For more information on visualization, including information on how to
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install and run DAWN, OpenGL and HepRApp, see the visualization tutorials,
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for example,
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http://geant4.slac.stanford.edu/Presentations/vis/G4[VIS]Tutorial/G4[VIS]Tutorial.html
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(where [VIS] can be replaced by DAWN, OpenGL and HepRApp)
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The tracks are automatically drawn at the end of each event, accumulated
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for all events and erased at the beginning of the next run.
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B- USER INTERFACES
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The user command interface is set via the G4UIExecutive class
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in the the main() function in exampleB1.cc
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The selection of the user command interface is then done automatically
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according to the Geant4 configuration. The default command interface,
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called G4UIterminal, is done via a standard G4cin/G4cout.
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On Linux and Sun-cc one can use a smarter command interface G4UItcsh.
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It is enough to set the environment variable G4UI_USE_TCSH before compiling
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exampleB1.cc
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C- HOW TO RUN
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- compile and link to generate an executable
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% cd B1
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% make
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- execute exampleB1 in the 'interactive mode' with visualization:
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% exampleB1
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and type in the commands from run1.mac line by line:
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Idle> /control/verbose 2
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Idle> /tracking/verbose 1
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Idle> /run/beamOn 10
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Idle> ...
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Idle> exit
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or
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Idle> /control/execute run1.mac
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....
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Idle> exit
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- execute exampleB1 in the 'batch' mode from macro files
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(without visualization)
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% exampleB1 run2.mac
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% exampleB1 exampleB1.in > exampleB1.out
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