[807] | 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 | Extended Example for G4GeneralParticleSource (GPS) |
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| 7 | --------------------------------------- |
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| 8 | |
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| 9 | exGPS is created to demonstrate the usage of G4GeneralParticleSource for generating |
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| 10 | primary incident particle according to user defined distributions. These range from simple |
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| 11 | monocromatic point source to complicated mutiple sources with various biasing schemes. |
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| 12 | |
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| 13 | More detailed information on the usage of GPS are available on its home site: |
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| 14 | http://reat.space.qinetiq.com/gps |
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| 15 | |
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| 16 | ------------------------------------------------------------------------------------------- |
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| 17 | 1. GEOMETRY |
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| 18 | |
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| 19 | Simple geometry consists of a "Vacuum" world and, in it with two other components: |
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| 20 | |
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| 21 | - An alunimium box : 20 x 20 x 20 cm in size, cerntered at the origin. |
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| 22 | |
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| 23 | - A SiO2 sphere: 5 cm in radius and is placed in the centre of the aluminium box. |
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| 24 | |
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| 25 | 2. PHYSICS |
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| 26 | |
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| 27 | Tranportation process only for all particles. |
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| 28 | |
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| 29 | 3. EVENT: |
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| 30 | |
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| 31 | The event generator is the G4GeneralParticleSource (GPS). The instantiation of G4GeneralParticleSource |
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| 32 | is same as that for G4ParticleGun. See the exGPSPrimaryGeneratorAction.cc file for details . |
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| 33 | |
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| 34 | 5. VISUALIZATION: |
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| 35 | |
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| 36 | Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An |
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| 37 | example of displaying the geometry and tracks using VRML is given in the macro file display_vrml.mac. |
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| 38 | |
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| 39 | 6. ANALYSIS: |
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| 40 | |
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| 41 | This example implements an AIDA-compliant analysis manager which creates histograms and ntuples. |
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| 42 | If user has an AIDA-compliant tool such as AIDAJNI, ANAPHE, or PI installed on his/her system, |
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| 43 | the analysis part of this example can be activated by: |
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| 44 | |
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| 45 | setenv G4ANALYSIS_USE 1 |
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| 46 | |
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| 47 | This needs to be done before building the executable. |
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| 48 | |
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| 49 | At the end of an excution, an xml file "exgps.aida" is created by default which contains |
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| 50 | histograms and ntuples. User can change the name and type of this output file with the commands |
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| 51 | |
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| 52 | /analysis/filetype new-type |
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| 53 | /analysis/fileName new-filename |
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| 54 | |
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| 55 | e.g. |
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| 56 | |
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| 57 | /analysis/filetype hbook |
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| 58 | /analysis/filename exgps.hbook |
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| 59 | |
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| 60 | these change the output file type to "hbook" and name to "exgps.hbbok" |
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| 61 | |
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| 62 | The output file conatins 6 histograms and one ntuple: |
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| 63 | |
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| 64 | histogram 1: The energy spectrum of the primary particles. |
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| 65 | histogram 2: 2d histogram of primary particle incident position distribution in the X-Y plane. |
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| 66 | histogram 3: 2d histogram of primary particle incident position distribution in the X-Z plane. |
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| 67 | histogram 4: 2d histogram of primary particle incident position distribution in the Y-Z plane. |
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| 68 | histogram 5: 2d histogram of primary particle incident angle distribution in terms of Phi/Cos(Theta). |
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| 69 | histogram 6: 2d histogram of primary particle incident angle distribution in terms of Phi/Theta. |
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| 70 | |
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| 71 | The binnings of the histograms can be changed with the UI commands avialable under the |
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| 72 | /analysis directory. |
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| 73 | |
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| 74 | In the ntuple the following data are recorded for each incident particle: |
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| 75 | |
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| 76 | Particle Name |
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| 77 | Incident Position (x,y,z); |
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| 78 | Incident Angle (theta,phi); |
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| 79 | Particle weight; |
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| 80 | |
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| 81 | |
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| 82 | 7. GETTING STARTED: |
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| 83 | |
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| 84 | i) If you have an AIDA-compliant analysis package installed, then you should switch on the analysis |
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| 85 | part of the example by: |
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| 86 | |
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| 87 | setenv G4ANALYSIS_USE 1 |
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| 88 | |
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| 89 | otherwise make sure the G4ANALYSIS_USE is not defined: |
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| 90 | |
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| 91 | unsetenv G4ANALYSIS_USE |
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| 92 | |
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| 93 | ii) Build the exGPS executable: |
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| 94 | |
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| 95 | cd to exgps |
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| 96 | gmake clean |
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| 97 | gmake |
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| 98 | |
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| 99 | gmake will create tmp and bin directories in your $G4TMP and $G4BIN directories. |
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| 100 | The executable, named exGPS, will be created in the $G4BIN/$G4SYSTEM/ directory. |
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| 101 | |
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| 102 | iii) Run the executable: |
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| 103 | |
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| 104 | while in the exgps directory do |
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| 105 | |
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| 106 | $G4BIN/$G4SYSTEM/exGPS exrgps.in |
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| 107 | |
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| 108 | If G4ANALYSIS_USE is defined, one should see a display of the six histograms. If JAIDA is used, one has |
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| 109 | to close the plotter window in order to terminate the execution. After the termination one will find |
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| 110 | the "exgps.aida", as well as a vrml file "g4_00.wrl" in the directory. |
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| 111 | |
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| 112 | 8. FURTHER EXAMPLES of MACRO FILES: |
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| 113 | |
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| 114 | There are a number of g4mac files in the ./macros subdirectory, to show the various features of GPS. |
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| 115 | Most of them will lead to the creation of an aida file in the same name as the macro file. |
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| 116 | These aida files can be examed and analysed with an analysis tool such as JAS3. |
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| 117 | |
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| 118 | Please see the README file there for further information. |
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| 119 | |
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| 120 | |
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| 124 | |
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