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0001
0002 =========================================================
0003 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0004 =========================================================
0005
0006 lArCal
0007 --------
0008
0009 This example is intended to simulate the Forward Liquid Argon Calorimeter
0010 (FCAL) of the ATLAS Detector at LHC. The goal of the FCAL is to provide
0011 a good missing energy determination in the region of very small angles
0012 from the beam direction.
0013
0014
0015 1. GEOMETRY DEFINITION
0016 ------------------------
0017
0018 The liquid Argon calorimeter consists of three modules with the same
0019 nominal outer dimensions: an electromagnetic module (made
0020 of copper) followed by two hadronic ones (made of tungsten alloy).
0021 The corresponding parameters of these modules are defined inside the
0022 FCALEMModuleParameters.input and FCALHadModuleParameters.input files.
0023 The package contains as well a FCALTestbemSetup class whose geometry is given by
0024 FCALTestbeamSetupParameters.input. See these files for details concerning to
0025 radius, lenght and angles of the different components.
0026
0027
0028 2. AN EVENT : THE PRIMARY GENERATOR
0029 ------------------------------------
0030
0031 The primary kinematic consists of a single particle which hits the
0032 geometry perpendicular to the input face. The FCALPrimaryGeneratorAction
0033 class gives the particle and its energy (by default it is an electron of
0034 20 GeV). These parameters can be changed in commands of ParticleGun class
0035 inside the macros given in this example.
0036
0037 The subdirectory data-tracks contains the kinematic files
0038 of the particles for different energies (20 GeV, 40 GeV, 60 GeV, 80 GeV,
0039 120 GeV and 200 GeV).
0040 The information given inside these files are the X, Y, Z and cosX,
0041 cosY, cosZ variables for each event.
0042
0043 A RUN is a set of events.
0044
0045
0046 3. VISUALIZATION
0047 ------------------
0048
0049 The Visualization Manager is set in the main().
0050 The initialisation of the drawing is done via the command
0051 > /control/execute vis.mac
0052
0053 The detector has a default view which is a transversal view of the geometry.
0054
0055 The tracks are drawn at the end of event, and erased at the end of run.
0056 Optionally the way of drawing the particles can be changed in the
0057 TBEVentActionMessenger class.
0058
0059
0060 4. PHYSICS
0061 ----------
0062
0063 You can select between 4 Physics Lists: QGSP, LHEP, QGSC, QGSP_BIC_EMY.
0064 The last one is set as default, so that you can test the low-energy
0065 electromagnetic.
0066 The selection is done simply by comment/uncomment a line in the main
0067 lArCal.cc (look for the keyword ***LOOKHERE***).
0068
0069
0070 5. HOW TO START ?
0071 -----------------
0072
0073 - compile and link to generate an executable
0074 % cd geant4/examples/advanced/lAr_calorimeter
0075 % gmake
0076
0077 - execute the program in 'batch' mode from macro files
0078 % lArCal prerunlArcal.mac
0079
0080 - execute Test in 'interactive mode' with visualization
0081 % lArCal
0082 ...
0083 Idle> type your commands
0084 ...
0085 Idle> exit
0086
0087
0088 6. HISTOGRAMS
0089 --------------
0090 The analysis is performed using the histogramming tools provided by
0091 Geant4. No external dependencies are required.
0092
0093 lArCal produces 4 histograms (saved as fcal.root) which illustrate
0094 the final state of the most important variables of the example:
0095
0096 Histo1 --> Number of tracks out of World
0097 Histo2 --> Number of secondary particles
0098 Histo3 --> Total energy deposited (in MeV) in the electromagnetic module
0099 Histo4 --> Total energy deposited (in MeV) in the hadronic module
0100
0101 See their definitions in FCALRunAction.cc
0102
0103 The histograms are saved (default) as a ROOT file. It is possible to save the
0104 histograms in a xml file by changing the G4AnalysisManager default file type
0105 in the FCALRunAction constructor.
0106
