Gabriele Cosmo
107 lines
3.7 KiB
Plaintext
107 lines
3.7 KiB
Plaintext
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=========================================================
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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=========================================================
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lArCal
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--------
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This example is intended to simulate the Forward Liquid Argon Calorimeter
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(FCAL) of the ATLAS Detector at LHC. The goal of the FCAL is to provide
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a good missing energy determination in the region of very small angles
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from the beam direction.
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1. GEOMETRY DEFINITION
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------------------------
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The liquid Argon calorimeter consists of three modules with the same
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nominal outer dimensions: an electromagnetic module (made
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of copper) followed by two hadronic ones (made of tungsten alloy).
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The corresponding parameters of these modules are defined inside the
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FCALEMModuleParameters.input and FCALHadModuleParameters.input files.
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The package contains as well a FCALTestbemSetup class whose geometry is given by
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FCALTestbeamSetupParameters.input. See these files for details concerning to
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radius, lenght and angles of the different components.
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2. AN EVENT : THE PRIMARY GENERATOR
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------------------------------------
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The primary kinematic consists of a single particle which hits the
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geometry perpendicular to the input face. The FCALPrimaryGeneratorAction
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class gives the particle and its energy (by default it is an electron of
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20 GeV). These parameters can be changed in commands of ParticleGun class
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inside the macros given in this example.
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The subdirectory data-tracks contains the kinematic files
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of the particles for different energies (20 GeV, 40 GeV, 60 GeV, 80 GeV,
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120 GeV and 200 GeV).
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The information given inside these files are the X, Y, Z and cosX,
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cosY, cosZ variables for each event.
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A RUN is a set of events.
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3. VISUALIZATION
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------------------
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The Visualization Manager is set in the main().
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The initialisation of the drawing is done via the command
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> /control/execute vis.mac
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The detector has a default view which is a transversal view of the geometry.
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The tracks are drawn at the end of event, and erased at the end of run.
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Optionally the way of drawing the particles can be changed in the
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TBEVentActionMessenger class.
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4. PHYSICS
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----------
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You can select between 4 Physics Lists: QGSP, LHEP, QGSC, QGSP_BIC_EMY.
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The last one is set as default, so that you can test the low-energy
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electromagnetic.
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The selection is done simply by comment/uncomment a line in the main
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lArCal.cc (look for the keyword ***LOOKHERE***).
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5. HOW TO START ?
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-----------------
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- compile and link to generate an executable
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% cd geant4/examples/advanced/lAr_calorimeter
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% gmake
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- execute the program in 'batch' mode from macro files
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% lArCal prerunlArcal.mac
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- execute Test in 'interactive mode' with visualization
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% lArCal
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...
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Idle> type your commands
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...
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Idle> exit
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6. HISTOGRAMS
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--------------
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The analysis is performed using the histogramming tools provided by
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Geant4. No external dependencies are required.
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lArCal produces 4 histograms (saved as fcal.root) which illustrate
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the final state of the most important variables of the example:
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Histo1 --> Number of tracks out of World
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Histo2 --> Number of secondary particles
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Histo3 --> Total energy deposited (in MeV) in the electromagnetic module
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Histo4 --> Total energy deposited (in MeV) in the hadronic module
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See their definitions in FCALRunAction.cc
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The histograms are saved (default) as a ROOT file. It is possible to save the
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histograms in a xml file by changing the G4AnalysisManager default file type
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in the FCALRunAction constructor.
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