Geant4 Compatibility: Geant4.10
Geant4 simulation of the Hybrid Detector for the DRAGON experiment @ TRIUMF
Author: Devin Burke Email: burkeds@mcmaster.ca
McMaster University
Department of Physics and Astronomy
GEANT4 source code for an application simulating a hybrid ionization chamber / double-sided-silicon strip detector to operate as a dE vs E detector for heavy ions within astrophysical energy ranges.
The application is written in C++ and uses the GEANT4 simulation toolkit as well as standard C++ libraries. This application builds from previous work done by Dario Gigliotti and from the GEANT4 example application TESTEM7. The source code can be compiled using cmake in the standard way most GEANT4 applications can be compiled (i.e. - performing an "out of source" build as is described here):
mkdir build
cd build
cmake $PATH_TO_SOURCE$
make -jn
where n is the number of cores you wish to use.
Commands can be entered from the UI or from batch. To run a macro from batch enter:
./Hybrid $MACRO$ > $G4cout_OUTPUT_FILE$
To run a macro from the UI use the command:
/control/execute $MACRO$
The application opens in the pre-initialization stage. Here the user can set detector geometries and material types. Type ls to see the list of commands.
App-specific commands are located in the testem command directory. Associated help commands can be entered to explain their function and a list can be seen in the source code file DetectorMessenger.cc. All UI commands are defined within their associated messenger source code files.
All materials and geometry can be defined from the UI commands provided the materials are defined in DetectorConstruction.cc with the exception of the DSSSD dead layer which must currently be altered in the source code.
Isobutane pressure can be set from 1 to 31 torr by entering the command:
/testem/det/setGasMat isobutane$Ptorr
where $P is an integer from 1 to 31.
There is nothing stopping the user from defining other pressures within the source code. Just add the
material in DetectorConstruction.cc.
The length of the gas chamber along the beam axis can be set by:
/testem/det/setGasThick
The sensitive regions of the gas can be set by three commands:
/testem/det/setAnodePosition #sets the origin of the sensitive region
/testem/det/setAnodeLength #sets the region length along the beam axis
/testem/det/setSegmentLength #divides the length into equal segments with dead regions
#if the lengths do not divide evenly into the total length.
Once detector parameters are set the user should enter the initialized stage.
/run/initialize
From here the user can specify the parameters of the general particle source (GPS). The GPS is unaltered from the Geant4 tool and the user can see the Geant4 documentation for instruction in its use.
As an example, to specify a beam of carbon ions, one may issue the following commands:
/gps/particle ion #specify an ion type projectile
/gps/ion 6 12 0 #The ion has Z=6 A=12 Q=0
/gps/ene/type Gauss #PDF from which the ion energy is sampled.
/gps/ene/mono 10 MeV #Mean energy of ion PDF
/gps/ene/sigma 1 MeV #Standard deviation of ion energy PDF
/gps/pos/type Beam #Specifies a beam type position distribution
/gps/pos/sigma_r 2 mm #Set STDEV in radial of the beam positional profile
/gps/pos/rot1 0 0 1 #Set the 1st vector defining the rotation matrix
/gps/ang/type beam1d #Specifies a 1D beam angular distribution
/gps/ang/sigma 10 mrad #Set STDEV of the angular distribution
/gps/ang/rot1 0 0 1
/run/beamOn 1000 #Begins a run with 1000 events
Simulation results are displayed in the GEANT4 window at the end of the run. Results are also recorded in text files within the application directory as well as a ROOT tree. Efficiency is calculated and displayed in the GEANT4 window. It is the ratio of event hits to total events. In this application an event is considered a hit when the primary event stops within the active region of the DSSSD volume.