| 1 | $Id: README,v 1.4 2008/09/26 20:26:01 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 | TestEm18 |
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| 9 | -------- |
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| 10 | This example allows to study the energy lost by a charged particle in a |
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| 11 | single layer, due to ionization and bremsstrahlung. Results are compared to |
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| 12 | 'reference' values. |
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| 13 | |
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| 14 | 1- GEOMETRY DEFINITION |
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| 15 | |
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| 16 | It is a single box of homogeneous medium. |
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| 17 | Two parameters define the geometry : |
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| 18 | - the material of the box, |
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| 19 | - the (full) size of the box. |
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| 20 | |
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| 21 | The default geometry (1 cm of water) is constructed in DetectorConstruction, |
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| 22 | but the above parameters can be changed interactively via the commands |
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| 23 | defined in DetectorMessenger. |
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| 24 | |
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| 25 | 2- PHYSICS |
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| 26 | |
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| 27 | The physics list contains the 'standard' electromagnetic processes. |
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| 28 | However the MultipleScattering is not registered, in order to focuse on |
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| 29 | fluctuations due to energy loss alone. |
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| 30 | |
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| 31 | 3- BEAM |
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| 32 | |
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| 33 | The primary kinematic is a single particle starting at the edge |
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| 34 | of the box. The type of the particle and its energy are set in |
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| 35 | PrimaryGeneratorAction (e- 10 MeV), and can be changed via the G4 |
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| 36 | build-in commands of ParticleGun class. |
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| 37 | |
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| 38 | 4- RUN |
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| 39 | |
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| 40 | During the tracking of the incident particle, the secondary particles |
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| 41 | are immediately killed, after that their energy has been registered |
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| 42 | (see StackingAction). |
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| 43 | Therefore, we study here the total energy lost by the incident particle, |
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| 44 | not the energy deposited in a layer of finite thickness. |
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| 45 | |
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| 46 | At EndOfRun, the above results are compared with 'reference' values, |
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| 47 | i.e. the values read from EnergyLoss tables. |
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| 48 | |
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| 49 | 5- HISTOGRAMS |
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| 50 | |
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| 51 | The test contains 6 built-in 1D histograms, which are managed by the |
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| 52 | HistoManager class and its Messenger. |
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| 53 | |
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| 54 | 1 continuous energy loss along primary track |
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| 55 | 2 energy from secondaries |
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| 56 | 3 total energy lost by primary track (1+2) |
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| 57 | 4 energy spectrum of e-+ |
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| 58 | 5 energy spectrum of gamma |
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| 59 | 6 step size of primary track |
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| 60 | |
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| 61 | The histos can be activated individually with the command : |
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| 62 | /testem/histo/setHisto id nbBins valMin valMax unit |
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| 63 | where 'unit' is the desired unit for the histo (MeV or KeV, cm or mm, etc..) |
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| 64 | |
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| 65 | One can control the name and the type of the histograms file with |
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| 66 | the commands: |
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| 67 | /testem/histo/setFileName name (default testem18) |
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| 68 | /testem/histo/setFileType name (default root) |
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| 69 | |
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| 70 | It is also possible to print selected histograms on an ascii file: |
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| 71 | /testem/histo/printHisto id |
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| 72 | All selected histos will be written on a file name.ascii (default testem18) |
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| 73 | |
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| 74 | Note that, by default, histograms are disabled. To activate them, uncomment |
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| 75 | the flag G4ANALYSIS_USE in GNUmakefile. |
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| 76 | |
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| 77 | 6- VISUALIZATION |
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| 78 | |
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| 79 | The Visualization Manager is set in the main(). |
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| 80 | The initialisation of the drawing is done via the commands |
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| 81 | /vis/... in the macro vis.mac. To get visualisation: |
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| 82 | > /control/execute vis.mac |
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| 83 | |
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| 84 | The detector has a default view which is a longitudinal view of the box. |
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| 85 | The tracks are drawn at the end of event, and erased at the end of run. |
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| 86 | |
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| 87 | 7- HOW TO START ? |
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| 88 | |
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| 89 | compile and link to generate an executable |
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| 90 | % cd geant4/examples/extended/electromagnetic/TestEm18 |
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| 91 | % gmake |
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| 92 | |
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| 93 | execute TestEm18 in 'batch' mode from macro files : |
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| 94 | % TestEm18 electron.mac.mac |
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| 95 | |
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| 96 | execute TestEm18 in 'interactive mode' with visualization : |
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| 97 | % TestEm18 |
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| 98 | Idle> control/execute vis.mac |
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| 99 | .... |
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| 100 | Idle> type your commands |
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| 101 | .... |
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| 102 | Idle> exit |
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| 103 | |
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| 104 | 8- USING HISTOGRAMS |
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| 105 | |
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| 106 | By default the histograms are not activated. To activate histograms |
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| 107 | the environment variable G4ANALYSIS_USE should be defined. For instance |
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| 108 | uncomment the flag G4ANALYSIS_USE in GNUmakefile. |
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| 109 | |
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| 110 | Before compilation of the example it is optimal to clean up old files: |
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| 111 | gmake histclean |
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| 112 | gmake |
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| 113 | |
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| 114 | To use histograms, at least one of the AIDA implementations should be |
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| 115 | available. See InstallAida.txt |
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| 116 | |
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