Example P03

This example illustrates the use of the text geometry.

GEOMETRY EXAMPLES

Several examples of text geometries are provided:

g4geom_simple.txt :

• Simple construction of materials and single placements

g4geom_matemixt.txt :

• Isotopes, elements and materials

g4geom_boolean.txt :

• Boolean solids

g4geom_reflections.txt :

• Reflections

g4geom_replicas.txt :

• Replicas

g4geom_divisions.txt :

• Divisions

g4geom_paramLinear.txt :

• Linear parameterisations

g4geom_paramSquare.txt :

• Square parameterisations

g4geom_assembly.txt :

• Assembly placements

HOW TO START ?

Execute textGeom in 'batch' mode from macro file

% textGeom run.mac

It will read the geometry from a file named 'g4geom.txt', and it will create a VRML2 file to visualise the geometry. Therefore if you want to try any of the above-mentioned files, copy it to a file with this name,

DEFINING A SENSITIVE DETECTOR

The detector construction class ExTGDetectorConstructionWithSD shows how to access a volume of the text geometry and assign to it a sensitive detector. To use it, replace at exampleTextGeom.cc the line

runManager->SetUserInitialization(new ExTGDetectorConstruction);

by

runManager->SetUserInitialization(new ExTGDetectorConstructionWithSD);

and recompile.

It will use the geometry from the file 'g4geom_SD.txt'

MIXING TEXT AND C++ GEOMETRIES <br>

The detector construction class ExTGDetectorConstructionWithCpp shows how to create a volume with C++ and place it in the world or inside a volume defined in the text geometry. To use it, replace at exampleTextGeom.cc the line

runManager->SetUserInitialization(new ExTGDetectorConstruction);

by

runManager->SetUserInitialization(new ExTGDetectorConstructionWithCpp);

and recompile.

It will use the geometry from the file 'g4geom_simple.txt'

CREATING NEW TAGS IN THE TEXT GEOMETRY: DEFINING CUTS PER REGION

The detector construction class ExTGDetectorConstructionWithCuts, together with ExTGRCLineProcessor, ExTGRCDetectorBuilder, ExTGRCRegionCutsMgr and ExTGRCRegionData show how to add a couple of tags, ':REGION' and ':CUT', that allow to define cuts per region in your input geometry text file. To use it, replace at exampleTextGeom.cc the line

runManager->SetUserInitialization(new ExTGDetectorConstruction);

by

runManager->SetUserInitialization(new ExTGDetectorConstructionWithCuts);

and recompile.

It will use the geometry from the file 'g4geom_cutsPerRegion.txt'

DUMP THE IN-MEMORY GEOMETRY TO TEXT FILE

The run action, ExTGRunAction, triggers the writing of the in-memory Geant4 geometry to a text file. To use it you just have to uncomment in exampleTextGeom.cc the line

runManager->SetUserAction(new ExTGRunAction);

and it will read the geometry from the file 'g4geom.txt' and will write the geometry in a file named 'geom.txt'