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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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HADR00
V.Ivanchenko
CERN, Geneva, Switzerland
This example demonstrates a usage of G4PhysListFactory to build
Physics List and G4HadronicProcessStore to access cross sections.
GEOMETRY
The Target volume is a cilinder placed inside the World volume. Follwoing
UI commands are available to modify the geometry:
/testhadr/TargetMat G4_Pb
/testhadr/WorldMat G4_AIR
/testhadr/TargetRadius 10 mm
/testhadr/TargetLength 20 cm
If geometry was changed between two runs, then the follwoing command need to
be executed:
/testhadr/update
By default beam direction coinsides with the target axis and is Z axis
in the global coordinate system. The beam starts in the middle of the target.
G4ParticleGun is used as a primary generator. The energy and the type of
the beam can be defined via standard UI commands
/gun/energy 15 GeV
/gun/particle proton
PHYSICS
Physics List is defined by the PHYSLIST environment variable. By default
QGSP_BERT Physics List will be instantiated.
CROSS SECTION
At the end of any run the set of cross sections is built and can be printed
out for a given progectile particle and a target element, which can be
defined via UI commands:
/testhadr/particle pi+
/testhadr/targetElm Pb
/testhadr/verbose 1
The level verbosity above zero provides printout of the cross section table.
The energy/momentum limits and number of bins can be set via UI commands:
/testhadr/nBinsE 900
/testhadr/nBinsP 700
/testhadr/minEnergy 1 keV
/testhadr/maxEnergy 1 TeV
/testhadr/minMomentum 1 MeV
/testhadr/maxMOmentum 10 TeV
VISUALISATION
For interactive mode G4 visualization options and variables should be
defined, then the example should be recompiled:
gmake visclean
gmake
The vis.mac file can be used an example of visualization. The following
command can be used:
/testhadr/DrawTracks charged
/testhadr/DrawTracks neutral
/testhadr/DrawTracks all
HISTOGRAMS
All histograms are provided in decimal logarithmic scale (log10(E/MeV)
and log10(p/GeV)) for one projectile particle and one target element.
The element is taken from the Geant4 NIST datebase, natural isotope
composition is assumed.
To use histograms any of implementations of AIDA interfaces should
be available (see http://aida.freehep.org).
For example, if iAIDA is installed and compiled at SLC4 Linux
setenv AIDA_DIR $MYPACKAGES/analysis/iAIDA/install/slc4_amd64_gcc34_root
setenv PATH ${PATH}:${AIDA_DIR}/bin
Before compilation of the example it is optimal to clean up old
object files:
gmake histclean
setenv G4ANALYSIS_USE 1
gmake
It is possible to choose the format of the output file with
histograms using UI command:
/testhadr/HistoName name
/testhadr/HistoType type
/testhadr/HistoOption "uncompress"
The following types are available: hbook, root, aida. They will be
stored in the file "name.hbook", "name.root", or "name.aida".
To show the contence of a histogram ID=i the commands may be applied:
/testhadr/HistoPrint i
Gabriele Cosmo