$Id: README,v 1.12 2008/08/22 14:35:12 vnivanch Exp $
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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TestEm9
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Demonstrate electromagnetic physics in crystal calorimeters.
How to define cut-per-region.
1- GEOMETRY DEFINITION
The geometry consists of the vertex detector (VD), the electromagnetic
calorimeter (EM), and the muon identifier (MU). Detector layout along
the axis Z.
VD consisted of 3 layers of Si with pads structured along the axis X.
Between VD and EM there are 2 active absorbers (scintillators).
EM is the matrix 5x5 of heavy crystals. MU consist of 2 active absorbers
(scintillators) and the iron plate between.
2 additional to the World regions are defined: VertexDetector and
MuonDetector. For testing purposes first absorber of MU is included in
the region of VD.
Material of calorimiter and absorber can be choosen:
Air Water lAr Al Fe BGO PbWO4 Pb.
eg: /testem/det/CalMat PbWO4
/testem/det/AbsMat Al
The size of the detector can be changed also.
eg: /testem/det/EcalLength 20 cm
/testem/det/EcalWidth 5 cm
/testem/det/update ---> rebuild the geometry
2- PHYSICS LISTS
Physics Lists are based on modular design. Few modules are instantiated:
1. Transporatation
2. EM physics
3. Decays
4. StepMax - for steplimitation
The following options for EM physics using builders from physics_lists
sub-package are available:
- "emstandard" (default)
- "emstandard_opt1" (EMV)
- "emstandard_opt2" (EMX)
- "emstandard_opt3" recommended for medical and space applications
There are local to this example variants of EM physics:
- "emstandard_local" close to opt3
- "standardIG" close to opt2
- "standardLPM" relativistic bremsstrahlung model added to opt1
- "Livermore" low-energy EM physics using Livermore data
- "Penelope" low-energy EM physics implementing Penelope models
Optional components can be added:
- "elastic" elastic scattering of hadrons
- "binary" QBBC configuration of hadron/ion inelastic models
- "gamma_nuc" gamma- and electro-nuclear processes
- "stopping" stopping processes
3- AN EVENT : THE PRIMARY GENERATOR
The primary kinematic consists of a single particle which hits the
cylinder perpendicular to the input face. The type of the particle
and its energy are set in the PrimaryGeneratorAction class, and can
changed via the G4 build-in commands of ParticleGun class.
4- OUTPUT
The batch regime of simulation can be started
$G4WORKDIR/bin/$G4SYSTEM/TestEm9 TestEm9.in
where TestEm9.in is the example of macro file for batch job.
As a result of simulation the number of secondaries produced
in different regions are averaged. The average energy depositions
in active absorbers and EM as well as RMS of these values are shown.
The number of hits in pads of VD is printed out.
5- VISUALISATION
To use visualisation the environment variable G4_VIS_USE should be
defined. An interactive session starts if no macro file is specified
in the command line:
$G4WORKDIR/bin/$G4SYSTEM/TestEm9
To start visualisation one can issur
>/control/execute vis.mac
>/run/beamOn 1
6- ANALYSIS
To create histograms/ntuple for further analysis one should define
environment variable G4ANALYSIS_USE and setup local AIDA implementation.
The example should be recompiled:
gmake histclean
gmake
The macro file csi.mac can be used as exmple of macro for analysis. It
can be executed in the following way:
$G4WORKDIR/bin/$G4SYSTEM/TestEm9 csi.mac
7- Using histograms
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By default the histograms are not activated. To activate histograms
the environment variable G4ANALYSIS_USE should be defined. For instance
uncomment the flag G4ANALYSIS_USE in GNUmakefile.
To use histograms any of implementations of AIDA interfaces should
be available. See InstallAida.txt
Gabriele Cosmo