1 | |
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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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