| 1 | $Id: README,v 1.3 2008/09/26 20:15:04 maire Exp $ |
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| 2 | ------------------------------------------------------------------- |
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| 3 | |
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| 4 | ========================================================= |
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| 5 | Geant4 - an Object-Oriented Toolkit for Simulation in HEP |
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| 6 | ========================================================= |
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| 7 | |
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| 8 | TestEm17 |
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| 9 | -------- |
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| 10 | This example is intended to check implementation of the processes |
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| 11 | of muon interactions: ionization, direct (e+,e-) production, |
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| 12 | bremsstrahlung, mu-nuclear interaction. |
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| 13 | It allows to compute differential cross sections (as function of the |
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| 14 | energy tranfered to secondaries), total cross sections and to compare |
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| 15 | with analytic calculations. |
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| 16 | |
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| 17 | 1- GEOMETRY DEFINITION |
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| 18 | |
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| 19 | It is a single box of homogeneous medium. |
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| 20 | Two parameters define the geometry : |
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| 21 | - the material of the box, |
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| 22 | - the (full) size of the box. |
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| 23 | |
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| 24 | The default geometry (1 m of Iron) is constructed in |
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| 25 | DetectorConstruction, but the above parameters can be changed |
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| 26 | interactively via the commands defined in DetectorMessenger. |
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| 27 | |
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| 28 | 2- PHYSICS LIST |
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| 29 | |
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| 30 | The physics list contains only electromagnetic processes for muon, |
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| 31 | adding G4MuNuclearInteraction and seting of upper energy range limit |
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| 32 | to 1000 PeV). |
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| 33 | |
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| 34 | Standard (default) and g4v52 (frozen at the release Geant4 v.5.2) |
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| 35 | physics can be choosen. |
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| 36 | |
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| 37 | 3- AN EVENT : THE PRIMARY GENERATOR |
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| 38 | |
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| 39 | The primary kinematic consists of a single particle starting at the edge |
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| 40 | of the box. The type of the particle and its energy are set in |
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| 41 | PrimaryGeneratorAction (mu+ 10 TeV), and can be changed via the G4 |
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| 42 | build-in commands of ParticleGun class (see the macros provided with |
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| 43 | this example). |
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| 44 | |
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| 45 | 4- PHYSICS |
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| 46 | |
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| 47 | The incident particle is a muon. During the tracking, secondary |
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| 48 | particles are killed. |
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| 49 | |
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| 50 | The number of interactions are plotted as a function of the energy |
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| 51 | transfered to the secondaries. |
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| 52 | The total number of interactions is recorded, and the total crossSection |
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| 53 | computed from this. |
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| 54 | |
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| 55 | At EndOfRun, the above results are compared with analytic calculations. |
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| 56 | The functions which compute the theoritical crossSections have been |
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| 57 | provided by the G4 MEPhI group, and grouped in MuCrossSection class. |
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| 58 | |
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| 59 | 5- HISTOGRAMS |
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| 60 | |
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| 61 | The test contains 4 built-in 1D histograms, which are managed by the |
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| 62 | HistoManager class and its Messenger. |
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| 63 | |
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| 64 | 1 Monte-Carlo relative transferred energy distribution histo |
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| 65 | (log10(eps/Emu kin) for knock-on electrons (ionization) |
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| 66 | 2 -"- direct (e+,e-) pair production |
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| 67 | 3 -"- bremsstrahlung |
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| 68 | 4 -"- nuclear interaction |
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| 69 | |
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| 70 | The histos can be activated individually with the command : |
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| 71 | /testem/histo/setHisto id nbBins valMin valMax : min and max values of |
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| 72 | log10(eps/Emu kin). |
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| 73 | |
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| 74 | At EndOfRun the corresponding histos for analytic calculations are |
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| 75 | automatically created anf filled (histo 6 to 9), and the comparison |
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| 76 | (G4 divided by theory) is done in histos 11 to 14. |
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| 77 | |
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| 78 | One can control the name and the type of the histograms file with |
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| 79 | the commands: |
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| 80 | /testem/histo/setFileName name (default testem17) |
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| 81 | /testem/histo/setFileType name (default root) |
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| 82 | |
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| 83 | Note that, by default, histograms are disabled. To activate them, |
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| 84 | uncomment the flag G4ANALYSIS_USE in GNUmakefile. |
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| 85 | |
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| 86 | 6- VISUALIZATION |
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| 87 | |
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| 88 | The Visualization Manager is set in the main(). |
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| 89 | The initialisation of the drawing is done via the commands |
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| 90 | /vis/... in the macro vis.mac. To get visualisation: |
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| 91 | > /control/execute vis.mac |
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| 92 | |
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| 93 | The detector has a default view which is a longitudinal view of the |
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| 94 | box. |
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| 95 | |
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| 96 | The tracks are drawn at the end of event, and erased at the end of run. |
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| 97 | |
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| 98 | 7- HOW TO START ? |
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| 99 | |
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| 100 | compile and link to generate an executable |
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| 101 | % cd geant4/examples/extended/electromagnetic/TestEm17 |
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| 102 | % gmake |
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| 103 | |
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| 104 | execute TestEm17 in 'batch' mode from macro files : |
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| 105 | % TestEm17 allproc.mac |
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| 106 | |
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| 107 | execute TestEm17 in 'interactive mode' with visualization : |
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| 108 | % TestEm17 |
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| 109 | Idle> control/execute vis.mac |
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| 110 | .... |
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| 111 | Idle> type your commands |
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| 112 | .... |
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| 113 | Idle> exit |
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| 114 | |
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| 115 | 8- USING HISTOGRAMS |
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| 116 | |
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| 117 | By default the histograms are not activated. To activate histograms |
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| 118 | the environment variable G4ANALYSIS_USE should be defined. For instance |
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| 119 | uncomment the flag G4ANALYSIS_USE in GNUmakefile. |
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| 120 | |
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| 121 | Before compilation of the example it is optimal to clean up old files: |
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| 122 | gmake histclean |
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| 123 | gmake |
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| 124 | |
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| 125 | To use histograms, at least one of the AIDA implementations should be |
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| 126 | available. See InstallAida.txt |
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| 127 | |
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