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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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HADR01
A.Bagulya, I.Gudowska, V.Ivanchenko, N.Starkov
CERN, Geneva, Switzerland
Karolinska Institute & Hospital, Stockholm, Sweden
Lebedev Physical Institute, Moscow, Russia
This example application is based on the application IION developed for
simulation of proton or ion beam interaction with a water target. Different
aspects of beam target interaction are demonstrating in the example including
longitudinal profile of energy deposition, spectra of secondary particles,
spectra of particles leaving the target. The results are presenting in a form
of average numbers and histograms.
GEOMETRY
The Target volume is a cylinder placed inside Check cylindrical volume. The
Check volume is placed inside the World volume. The radius and the length of
the Check volume are 1 mm larger than the radius and the length of the Target.
The material of the Check volume is the same as the World material. The World
volume has the sizes 10 mm larger than that of the Target volume. Any material
from the Geant4 database can be defined. The default World material is
G4Galactic and the default Target material is aluminum. The Target is
subdivided on number of equal slices. Following UI commands are available to
modify the geometry:
/testhadr/TargetMat G4_Pb
/testhadr/WorldMat G4_AIR
/testhadr/TargetRadius 10 mm
/testhadr/TargetLength 20 cm
/testhadr/NumberDivZ 200
Beam direction coincides with the target axis and is Z axis in the global
coordinate system. The beam starts 5 mm in front 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
Default beam position is -(targetHalfLength + 5*mm) and direction along Z axis.
Beam position and direction can be changed by gun UI commands:
/gun/position 1 10 3 mm
/gun/direction 1 0 0
however, position command is active only if before it the flag is set
/testhadr/DefaultBeamPosition false
SCORING
The scoring is performed with the help of UserStackingAction class and two
sensitive detector classes: one associated with a target slice, another with
the Check volume. Each secondary particle is scored by the StackingAction. In
the StackingAction it is also possible to kill all or one type of secondary
particles
/testhadr/Kill neutron
/testhadr/KillAllSecondaries
To control running the following options are available:
/testhadr/PrintModulo 100
/testhadr/DebugEvent 977
The last command selects an events, for which "/tracking/verbose 2" level
of printout is established.
PHYSICS
PhysicsList of the application uses reference Phsyics Lists or its components,
which are distributed with Geant4 in /geant4/physics_lists subdirectory.
The reference Physics List name may be defined in the 3d argument of the
run command:
Hadr01 my.macro QGSP_BERT
If 3d argument is not set then the PHYSLIST environment variable is checked.
If both are not defined then reference Phsyics Lists is not instantiated,
instead the local Physics List is used which is built from components using
UI interface. The choice of the physics is provided by the UI command:
/testhadr/Physics QGSP_BIC
To see the list of available configurations with UI one can use
/testhadr/ListPhysics
The cuts for electromagnetic physics can be established via
/testhadr/CutsAll 1 mm
/testhadr/CutsGamma 0.1 mm
/testhadr/CutsEl 0.2 mm
/testhadr/CutsPos 0.3 mm
/testhadr/CutsProt 0.6 mm
Note that testhadr UI commands are not available in the case when PHYSLIST
environment variable is defined.
VISUALIZATION
For interactive mode G4 visualization options and variables should be
defined, then the example should be recompiled:
gmake visclean
gmake
HISTOGRAMS
There are built in histograms. The 1st one (idx=0, id="1") scores energy
deposition along the target. Histograms "22", "23", "24", "25" scores
energy deposition per particle type.
All other histograms are provided in decimal logarithmic scale (log10(E/MeV),
where E is secondary particle energy at production
It is possible to change scale and output file name using UI commands:
/testhadr/histo/fileName name
/testhadr/histo/setHisto idx nbins vmin vmax unit
Only ROOT histograms are available.
All histograms are normalized to the number of events.
Gabriele Cosmo