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| 2 | ========================================================= |
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| 3 | Geant4 - an Object-Oriented Toolkit for Simulation in HEP |
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| 4 | ========================================================= |
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| 5 | |
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| 6 | lArCal |
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| 7 | -------- |
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| 8 | |
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| 9 | This example is intended to simulate the Forward Liquid Argon Calorimeter |
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| 10 | (FCAL) of the ATLAS Detector at LHC. The goal of the FCAL is to provide |
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| 11 | a good missing energy determination in the region of very small angles |
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| 12 | from the beam direction. |
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| 13 | |
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| 14 | |
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| 15 | 1. GEOMETRY DEFINITION |
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| 16 | ------------------------ |
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| 17 | |
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| 18 | The liquid Argon calorimeter consists of three modules with the same |
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| 19 | nominal outer dimensions: an electromagnetic module (made |
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| 20 | of copper) followed by two hadronic ones (made of tungsten alloy). |
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| 21 | The corresponding parameters of these modules are defined inside the |
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| 22 | FCALEMModuleParameters.input and FCALHadModuleParameters.input files. |
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| 23 | The package contains as well a FCALTestbemSetup class whose geometry is given by |
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| 24 | FCALTestbeamSetupParameters.input. See these files for details concerning to |
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| 25 | radius, lenght and angles of the different components. |
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| 26 | |
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| 27 | |
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| 28 | 2. AN EVENT : THE PRIMARY GENERATOR |
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| 29 | ------------------------------------ |
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| 30 | |
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| 31 | The primary kinematic consists of a single particle which hits the |
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| 32 | geometry perpendicular to the input face. The FCALPrimaryGeneratorAction |
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| 33 | class gives the particle and its energy (by default it is an electron of |
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| 34 | 80 GeV). These parameters can be changed in commands of ParticleGun class |
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| 35 | inside the macros given in this example. |
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| 36 | |
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| 37 | The subdirectory data-tracks contains the kinematic files |
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| 38 | of the particles for different energies (20 GeV, 40 GeV, 60 GeV, 80 GeV, |
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| 39 | 120 GeV and 200 GeV). |
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| 40 | The information given inside these files are the X, Y, Z and cosX, |
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| 41 | cosY, cosZ variables for each event. |
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| 42 | |
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| 43 | A RUN is a set of events. |
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| 44 | |
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| 45 | |
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| 46 | 3. VISUALIZATION |
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| 47 | ------------------ |
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| 48 | |
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| 49 | The Visualization Manager is set in the main(). |
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| 50 | The initialisation of the drawing is done via the command |
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| 51 | > /control/execute vis.mac |
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| 52 | |
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| 53 | The detector has a default view which is a transversal view of the geometry. |
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| 54 | |
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| 55 | The tracks are drawn at the end of event, and erased at the end of run. |
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| 56 | Optionally the way of drawing the particles can be changed in the |
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| 57 | TBEVentActionMessenger class. |
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| 58 | |
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| 59 | |
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| 60 | 4. PHYSICS |
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| 61 | ---------- |
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| 62 | |
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| 63 | You can select between 3 Physics Lists: QGSP (default), LHEP, QGSC. |
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| 64 | The selection is done simply by comment/uncomment a line in the main |
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| 65 | lArCal.cc (look for the keyword ***LOOKHERE***). |
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| 66 | |
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| 67 | |
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| 68 | 5. HOW TO START ? |
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| 69 | ----------------- |
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| 70 | |
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| 71 | - compile and link to generate an executable |
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| 72 | % cd geant4/examples/advanced/lAr_calorimeter |
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| 73 | % gmake |
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| 74 | |
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| 75 | - execute the program in 'batch' mode from macro files |
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| 76 | % lArCal prerunlArcal.mac |
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| 77 | |
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| 78 | - execute Test in 'interactive mode' with visualization |
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| 79 | % lArCal |
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| 80 | ... |
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| 81 | Idle> type your commands |
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| 82 | ... |
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| 83 | Idle> exit |
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| 84 | |
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| 85 | |
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| 86 | 6. HISTOGRAMS |
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| 87 | -------------- |
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| 88 | |
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| 89 | lArCal produces 4 histograms (saved as fcal.his) which illustrate |
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| 90 | the final state of the most important variables of the example: |
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| 91 | |
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| 92 | Histo1 --> Number of tracks out of World |
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| 93 | Histo2 --> Number of secondary particles |
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| 94 | Histo3 --> Total energy deposited (in MeV) in the electromagnetic module |
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| 95 | Histo4 --> Total energy deposited (in MeV) in the hadronic module |
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| 96 | |
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| 97 | See their definitions in FCALAnalysisManager.cc |
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| 98 | |
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| 99 | Note that histograms are disabled via the flag G4ANALYSIS_USE in GNUmakefile. |
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| 100 | |
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| 101 | |
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| 102 | 7. Using the PI implementation of the AIDA histograms: |
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| 103 | ------------------------------------------------------ |
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| 104 | |
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| 105 | In order to setup the proper environmental variables, needed for |
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| 106 | running AIDA / PI , run the script: |
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| 107 | |
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| 108 | --- For c-shell : source setupAidaPi.csh |
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| 109 | |
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| 110 | --- For bash-shell : . setupAidaPi.sh |
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| 111 | |
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| 112 | Notice that you need g++ 3.2 or 3.23. |
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| 113 | |
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| 114 | |
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