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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 vis.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, OpenScientist or PI installed on his/her system. Some URLs : |
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43 | http://aida.freehep.org/ |
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44 | http://java.freehep.org/aidajni |
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45 | http://www.cern.ch/PI |
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46 | http://OpenScientist.lal.in2p3.fr |
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47 | |
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48 | The analysis part of this example can be activated by doing a "source |
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49 | aida-setup" of the AIDA compliant tool (to activate the aida-config |
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50 | program) and by raising some environment variabless so that the |
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51 | G4 GNUmakefile system can take into account the AIDA tool. |
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52 | This can be done, for example on a UNIX under a csh like shell, with : |
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53 | csh> source <path_where_the_AIDA_tool_is_installed>/aida-setup.csh |
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54 | csh> aida-config # to check that this program is up and running |
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55 | G4 related part : |
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56 | csh> setenv G4ANALYSIS_USE 1 |
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57 | csh> setenv G4ANALYSIS_AIDA_CONFIG_CFLAGS `aida-config --include` |
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58 | csh> setenv G4ANALYSIS_AIDA_CONFIG_LIBS `aida-config --lib` |
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59 | |
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60 | (It may be usefull to note that in the G4 GNUmakefile system, |
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61 | the upper variables are used in the file config/analysis.gmk). |
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62 | |
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63 | This needs to be done before building the executable. |
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64 | |
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65 | At the end of an excution, an xml file "exgps.aida" is created by default which contains |
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66 | histograms and ntuples. User can change the name and format of this output file with the commands |
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67 | |
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68 | /analysis/filetype new-type |
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69 | /analysis/fileName new-filename |
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70 | |
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71 | e.g. |
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72 | |
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73 | /analysis/filetype root |
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74 | /analysis/filename myfile.root |
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75 | |
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76 | these change the output file format to ROOT and output file name to "myfile.root". There are three file |
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77 | formats to choose from: xml, root or hbook. |
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78 | |
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79 | The output file conatins 6 histograms and one ntuple: |
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80 | |
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81 | histogram 1: The energy spectrum of the primary particles. |
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82 | histogram 2: 2d histogram of primary particle incident position distribution in the X-Y plane. |
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83 | histogram 3: 2d histogram of primary particle incident position distribution in the X-Z plane. |
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84 | histogram 4: 2d histogram of primary particle incident position distribution in the Y-Z plane. |
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85 | histogram 5: 2d histogram of primary particle incident angle distribution in terms of Phi/Cos(Theta). |
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86 | histogram 6: 2d histogram of primary particle incident angle distribution in terms of Phi/Theta. |
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87 | |
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88 | The binnings of the histograms can be changed with the UI commands avialable under the |
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89 | /analysis directory. |
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90 | |
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91 | In the ntuple the following data are recorded for each incident particle: |
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92 | |
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93 | Particle ID |
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94 | Incident Position (x,y,z); |
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95 | Incident Angle (theta,phi); |
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96 | Particle weight; |
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97 | |
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98 | 7. GETTING STARTED: |
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99 | |
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100 | i) If you have an AIDA-compliant analysis package installed, then you should switch on the analysis |
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101 | part of the example by: |
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102 | |
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103 | setenv G4ANALYSIS_USE 1 |
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104 | |
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105 | otherwise do |
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106 | |
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107 | unsetenv G4ANALYSIS_USE |
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108 | |
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109 | to remove the generation of an output file. |
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110 | |
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111 | ii) Build the exGPS executable: |
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112 | |
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113 | cd to exgps |
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114 | gmake clean |
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115 | gmake |
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116 | |
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117 | gmake will create tmp and bin directories in your $G4TMP and $G4BIN directories. |
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118 | The executable, named exGPS, will be created in the $G4BIN/$G4SYSTEM/ directory. |
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119 | |
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120 | iii) Run the executable: |
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121 | |
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122 | while in the exgps directory do |
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123 | |
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124 | $G4BIN/$G4SYSTEM/exGPS exrgps.in |
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125 | |
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126 | If G4ANALYSIS_USE is defined, and dpends on the particular AIDA system used, e.g. JAIDA, one could see |
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127 | a display window of the six histograms. It may be neccessary to close the plotter window in order to |
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128 | terminate the execution. After the termination one will find the "exgps.aida", as well as a vrml file |
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129 | "g4_00.wrl" in the directory. |
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130 | |
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131 | 8. FURTHER EXAMPLES of MACRO FILES: |
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132 | |
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133 | There are a number of g4mac files in the ./macros subdirectory, to show the various features of GPS. |
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134 | Most of them will lead to the creation of an aida file in the same name as the macro file. |
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135 | These aida files can be examed and analysed with an analysis tool such as JAS3. |
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136 | |
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137 | Please see the README file there for further information. |
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138 | |
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139 | |
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140 | |
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