1 | $Id: README,v 1.26 2009/09/18 14:03:24 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 | TestEm5 |
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9 | ------- |
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10 | How to study the transmission, absorption and reflexion of particles through |
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11 | a single, thin or thick, layer of material. |
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12 | In perticular, the effects of the multiple scattering can be ploted. |
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13 | |
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14 | 1- GEOMETRY DEFINITION |
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15 | |
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16 | The "absorber" is a box made of a given material. |
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17 | |
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18 | Three parameters define the absorber : |
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19 | - the material of the absorber, |
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20 | - the thickness of an absorber, |
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21 | - the transverse size of the absorber (the input face is a square). |
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22 | |
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23 | A volume "World" contains the "absorber". |
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24 | |
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25 | In addition a transverse uniform magnetic field can be applied. |
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26 | |
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27 | The default geometry is constructed in DetectorConstruction class, but all the |
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28 | parameters can be changed via commands defined in the DetectorMessenger class. |
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29 | The parameters of the "World" can be changed, too. However, if World material |
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30 | is not set to vacuum, the plots 10->43 below may be not pertinent. |
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31 | |
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32 | 2- PHYSICS LIST |
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33 | |
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34 | Physics lists can be local (eg. in this example) or from G4 kernel |
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35 | physics_lists subdirectory. |
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36 | |
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37 | Local physics lists: |
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38 | - "local" standard EM physics with current 'best' options setting. |
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39 | these options are explicited in PhysListEmStandard |
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40 | - "standardSS" standard EM physics with single Coulomb scattering |
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41 | instead of multiple scattering |
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42 | |
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43 | From geant4/source/physics_lists/builders: |
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44 | - "emstandard_opt0" recommended standard EM physics for LHC |
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45 | - "emstandard_opt1" best CPU performance standard physics for LHC |
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46 | - "emstandard_opt2" |
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47 | - "emstandard_opt3" best current advanced EM options. |
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48 | analog to "local" above |
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49 | - "emlivermore" low-energy EM physics using Livermore data |
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50 | - "empenelope" low-energy EM physics implementing Penelope models |
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51 | |
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52 | Physics lists and options can be (re)set with UI commands |
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53 | |
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54 | Please, notice that options set through G4EmProcessOPtions are global, eg |
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55 | for all particle types. In G4 builders, it is shown how to set options per |
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56 | particle type. |
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57 | |
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58 | |
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59 | 3- AN EVENT : THE PRIMARY GENERATOR |
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60 | |
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61 | The primary kinematic consists of a single particle which hits the absorber |
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62 | perpendicular to the input face. The type of the particle and its energy are |
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63 | set in the PrimaryGeneratorAction class, and can be changed via the G4 build-in |
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64 | commands of ParticleGun class (see the macros provided with this example). |
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65 | |
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66 | In addition one can choose randomly the impact point of the incident particle. |
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67 | The interactive command is built in PrimaryGeneratorMessenger class. |
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68 | |
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69 | 4- VISUALIZATION |
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70 | |
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71 | The Visualization Manager is set in the main(). |
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72 | The initialisation of the drawing is done via the commands in vis.mac |
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73 | In interactive session: |
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74 | PreInit or Idle > /control/execute vis.mac |
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75 | |
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76 | The example has a default view which is a longitudinal view of the detector. |
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77 | |
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78 | The tracks are drawn at the end of event, and erased at the end of run. |
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79 | Optionaly one can choose to draw all particles, only the charged, or none. |
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80 | This command is defined in EventActionMessenger class. |
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81 | |
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82 | 5- TRACKING |
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83 | |
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84 | During the tracking, one can keep or not the secondaries : see StackingAction |
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85 | class and its Messenger. |
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86 | One can also limit 'by hand' the step lenght of the particle. As an example, |
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87 | this limitation is implemented as a 'full' process : see StepMax class and its |
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88 | Messenger. The 'StepMax process' is registered in the Physics List. |
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89 | |
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90 | 6- DETECTOR RESPONSE |
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91 | |
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92 | At the end of a run, from the histogram(s), one can study different |
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93 | physics quantities such as : |
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94 | - energy deposit in the absorber, |
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95 | - energy spectrum of secondaries at creation, |
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96 | - energy spectrum and angle distribution of particles at exit, |
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97 | - transmission and backscattering coefficients, |
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98 | - ... |
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99 | |
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100 | 7- List of the built-in histograms |
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101 | ---------------------------------- |
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102 | |
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103 | The test contains more than 20 built-in 1D histograms, which are managed by the |
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104 | HistoManager class and its Messenger. The histos can be individually activated |
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105 | with the command : |
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106 | /testem/histo/setHisto id nbBins valMin valMax unit |
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107 | where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..) |
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108 | (see the macros xxxx.mac). |
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109 | |
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110 | 1 "energy deposit in absorber" |
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111 | 2 "energy of charged secondaries at creation" |
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112 | 3 "energy of gammas at creation (log10(Ekin/MeV))" |
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113 | 4 "x_vertex of charged secondaries (all)" |
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114 | 5 "x_vertex of charged secondaries (not absorbed)" |
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115 | 10 "(transmit, charged) : kinetic energy at exit of world" |
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116 | 11 "(transmit, charged) : ener fluence: dE(MeV)/dOmega" |
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117 | 12 "(transmit, charged) : space angle dN/dOmega" |
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118 | 13 "(transmit, charged) : projected angle at exit of world" |
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119 | 14 "(transmit, charged) : projected position at exit of world" |
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120 | 15 "(transmit, charged) : radius at exit of world" |
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121 | 20 "(transmit, neutral) : kinetic energy at exit of world" |
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122 | 21 "(transmit, neutral) : ener fluence: dE(MeV)/dOmega" |
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123 | 22 "(transmit, neutral) : space angle dN/dOmega" |
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124 | 23 "(transmit, neutral) : projected angle at exit of world" |
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125 | 30 "(reflect , charged) : kinetic energy at exit of world" |
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126 | 31 "(reflect , charged) : ener fluence: dE(MeV)/dOmega" |
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127 | 32 "(reflect , charged) : space angle dN/dOmega" |
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128 | 33 "(reflect , charged) : projected angle at exit of world" |
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129 | 40 "(reflect , neutral) : kinetic energy at exit of world" |
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130 | 41 "(reflect , neutral) : ener fluence: dE(MeV)/dOmega" |
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131 | 42 "(reflect , neutral) : space angle dN/dOmega" |
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132 | 43 "(reflect , neutral) : projected angle at exit of world" |
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133 | |
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134 | The histograms can be viewed using ROOT or PAW. See below the note on AIDA. |
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135 | |
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136 | One can control the name and format of the histograms file with the command: |
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137 | /testem/histo/setFileName name (default testem5) |
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138 | /testem/histo/setFileType type (choice: hbook, root(default), XML) |
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139 | |
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140 | It is also possible to print selected histograms on an ascii file: |
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141 | /testem/histo/printHisto id |
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142 | All selected histos will be written on a file name.ascii (default testem5) |
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143 | |
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144 | Note that, by default, histograms are disabled. To activate them, uncomment |
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145 | the flag G4ANALYSIS_USE in GNUmakefile. |
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146 | |
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147 | 8- GEANT4/GEANT3/DATA COMPARISON |
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148 | |
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149 | A Geant4/Geant3/exp. data comparison is given here for a few cases. |
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150 | These cases can be classified as follow: |
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151 | - e-/e+ incident particles versus protons and others. |
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152 | - 3 energy regimes: low: < 1MeV; medium: 1MeV -> few 10MeV; high: > 100MeV |
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153 | |
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154 | We indicate here the corresponding macros. |
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155 | |
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156 | | low energy | medium energy | high energy |
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157 | -------------------------------------------------------- |
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158 | | acosta.mac | | |
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159 | e-+ | berger.mac | hanson.mac | |
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160 | | hunger.mac | kulchi.mac | |
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161 | | tavola.mac | | |
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162 | -------------------------------------------------------- |
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163 | others| bichsel.mac | vincour.mac | shen1.mac shen2.mac |
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164 | | | gottsch.mac | tramu.mac |
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165 | -------------------------------------------------------- |
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166 | |
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167 | The relevant part of the GEANT3 code is in the subdirectory geant3 together |
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168 | with the xxxx.dat input files. |
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169 | |
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170 | 9- HOW TO START ? |
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171 | |
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172 | - compile and link to generate an executable |
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173 | % cd TestEm5 |
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174 | % gmake |
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175 | |
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176 | - execute TestEm5 in 'batch' mode from macro files e.g. |
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177 | % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 myMacro.mac |
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178 | |
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179 | - execute TestEm5 in 'interactive' mode with visualization e.g. |
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180 | % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 |
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181 | Then type your commands, for instance : |
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182 | Idle> control/execute vis.mac |
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183 | Idle> run/beamOn 5 |
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184 | .... |
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185 | |
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186 | 10- USING HISTOGRAMS |
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187 | |
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188 | Note that, by default, histograms are disabled. To activate them, uncomment |
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189 | the flag G4ANALYSIS_USE in GNUmakefile. |
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190 | |
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191 | Before compilation of the example it is optimal to clean up old files: |
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192 | gmake histclean |
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193 | gmake |
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194 | |
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195 | To use histograms, at least one of the AIDA implementations should be |
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196 | available. See InstallAida.txt |
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197 | |
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