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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 G4RadioactiveDecay |
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7 | -------------------- |
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8 | |
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9 | The exRDM is created to show how to use the G4RadioactiveDecay process to simulate the decays of radioactive |
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10 | isotopes as well as the induced radioactivity resulted from nuclear interactions. In the example a simple |
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11 | geometry consists of a cylindric target placed in the centre of a tube shaped detector is used. Various primary event |
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12 | generation and tallying options are available. More documentations are available at |
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13 | |
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14 | http://reat.space.qinetiq.com/septimess/exrdm |
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15 | |
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16 | 1. GEOMETRY |
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17 | |
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18 | Material: There are 7 pre-defined materials: |
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19 | "Vacuum" "Air" "Silicon" "Aluminium" "Lead" "Germanium" and "CsI" |
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20 | |
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21 | User can add a new material at the "PreIni" state, using the command |
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22 | /geometry/material/add |
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23 | |
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24 | For the geometry, the world is filled with "Air" and there are two components in it |
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25 | |
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26 | - Target: A cylinder placed at the origin along the z-axis. The default size of the cylinder is |
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27 | 0.5 cm radius and 1 cm in length, and its default material is "CsI". |
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28 | |
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29 | - Detector:A tube cerntred at the origin along the z-axis, with inner radius matching the |
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30 | radius of the target. The default thickness of the tube is 2 cm and it is |
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31 | 5 cm long. The default material is "Germanium". |
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32 | |
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33 | The user can change the target/detector size and material at the at the "PreIni" state, using the commands under |
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34 | |
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35 | /exrdm/det |
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36 | |
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37 | |
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38 | 2. PHYSICS |
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39 | |
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40 | The following physics processes are included by default: |
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41 | |
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42 | - Standard electromagnetic: |
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43 | photo-electric effect |
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44 | Compton scattering |
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45 | pair production |
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46 | bremsstrahlung |
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47 | ionization |
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48 | multiple scattering |
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49 | annihilation |
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50 | |
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51 | - Decay |
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52 | |
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53 | - Radioactive Decay |
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54 | By default it is applied through out the geometry. The user can limit it to just the target by |
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55 | commands |
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56 | |
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57 | /grdm/noVolumes |
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58 | /grdm/selectVolume Target |
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59 | |
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60 | |
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61 | |
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62 | - Hadronic processes: |
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63 | Hadronic processes are not invoked by default. They can be activated by the user at the "PreIni" |
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64 | state of the execution via the command |
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65 | |
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66 | /exrdm/phys/SelectPhysics |
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67 | |
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68 | The options are: |
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69 | |
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70 | "Hadron" - Physicslist comsists of Binary_Cascade, HP_Neutron, QGSP, and LHEP, or |
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71 | the standdard hadron physics list avaible in the G4 distribution, i.e. |
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72 | "QGSP_BERT", "QGSP_BIC", "QGSP_HP", "LHEP_BERT", "LHEP_BERT_HP", "LHEP_BIC", |
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73 | "LHEP_BIC_HP". |
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74 | |
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75 | |
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76 | 3. EVENT: |
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77 | |
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78 | The event generator is based on the G4GeneralParticleSource (GPS) which allows the user to |
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79 | control all aspects of the initial states of the events. In this example, however, only simple features |
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80 | of the GPS are employed to generate the incident beam or the initial radio-isotopes. By default the |
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81 | incident particle is travelling along the + z-axis and the incident position is at the -Z end |
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82 | of the geometry. |
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83 | |
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84 | 4. DETECTOR RESPONSE: |
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85 | |
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86 | No Geant4 HITS and SD are defined in this example. All the relevant information of the simulation is extracted |
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87 | at the "UserSteppingAction" stage, if the variable "G4ANALYSIS_USE" is defined. These include: |
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88 | |
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89 | - Emission particles in the RadioactiveDecay process: |
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90 | particle PDGcode, |
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91 | partilce kinetic energy, |
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92 | particle creation time, |
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93 | particle weight. |
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94 | |
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95 | Note: the residual nuclei is not considered as an emitted particle. |
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96 | |
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97 | - Radio-Isotopes. All the radioactive isotopes produced in the simulation: |
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98 | isotope PDGcode, |
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99 | isotope creation time, |
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100 | isotope weight. |
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101 | |
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102 | - Energy depositions in the target and detector by prodicts of the RadioactiveDecay process: |
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103 | energy depostion (positive volue for target and negative for detector), |
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104 | time, |
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105 | weight. |
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106 | |
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107 | 5. VISUALIZATION: |
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108 | |
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109 | Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An |
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110 | example of display the geometry and tracks using VRML is given in the macro file macros/vrml.mac. |
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111 | |
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112 | 6. ANALYSIS: |
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113 | |
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114 | This example implements an AIDA-compliant analysis system as well as the ROOT file format for |
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115 | histograms and ntuples. If the the user has an AIDA-compliant tool such as |
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116 | AIDAJNI, ANAPHE, or PI installed on his/her system, the analysis part of this example can |
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117 | be activated by |
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118 | |
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119 | setenv G4ANALYSIS_USE_AIDA 1 |
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120 | |
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121 | before building the executable. The user can also add the "root" file format option by define |
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122 | |
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123 | setenv G4ANALYSIS_USE_RROT 1 |
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124 | |
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125 | before the compilation. |
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126 | |
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127 | At the completion of a simulation run a file "exrdm.root" by default is produced which contains |
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128 | these data structures. The user can change the name of this output file with the command |
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129 | |
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130 | /histo/fileName new-filename |
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131 | |
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132 | The output file by default is in "root" format and can be analysed offline using the ROOT tool, |
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133 | which allows the histograms and ntuples to examined, manipulated, saved and printed. |
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134 | |
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135 | User can also change the output file format to "hbook" or "xml" using the commands |
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136 | |
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137 | /histo/fileType hbook |
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138 | /histo/fileType xml |
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139 | |
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140 | The output file, in "xml" or "hbook" or "root" format, conatins the 3 ntuples (100,200,300) whose details have been |
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141 | described in section 4. In addition, there are 7 histograms in the file: |
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142 | |
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143 | histogram 10: The Pulse Height Spectrum (PHS) of the target. |
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144 | histogram 11: The PHS of the detector. |
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145 | histogram 12: The combined PHS of the target and detector. |
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146 | histogram 13: The anti-coincidece PHS of the target. |
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147 | histogram 14: The anti-coincidece PHS of the detector. |
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148 | histogram 15: The coincidece PHS between the target and detector. |
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149 | histogram 16: The emitted particle energy spectrum. |
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150 | |
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151 | The binnings of each histogram can be changed with the command |
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152 | |
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153 | /histo/setHisto |
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154 | |
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155 | It is assumed the detector and target pulses both have an integration time of 1 micro-second, and the |
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156 | coincidence gate is 2 microsecond wide. The target and detctor have a threshold of 10 keV in the |
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157 | anti-/coincidence modes. |
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158 | |
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159 | Histograms 10-15 were derived from the same data stored in ntuple-300(the energy depositions), while |
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160 | Histogram 16 is obtained with data in ntuple-100 (the emission particles). The user should be able to |
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161 | reproduce these histograms, or new histograms, with the ntuple data in an analyis tool such as JAS3. |
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162 | |
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163 | |
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164 | 7. GETTING STARTED: |
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165 | |
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166 | i) If you have an AIDA-compliant analysis system installed than you shall switch on the analysis part of |
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167 | example by |
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168 | |
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169 | setenv G4ANALYSIS_USE_AIDA 1 |
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170 | |
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171 | in addition if you want to add the ROOT file format, do |
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172 | |
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173 | setenv G4ANALYSIS_USE_ROOT 1 |
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174 | |
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175 | otherwise make sure the G4ANALYSIS_USE_AIDA and G4ANALYSIS_USE_ROOT are not definded |
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176 | |
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177 | unsetenv G4ANALYSIS_USE_AIDA |
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178 | unsetenv G4ANALYSIS_USE_ROOT |
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179 | |
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180 | ii) Build the exRDM executable: |
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181 | |
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182 | cd to exrdm |
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183 | gmake clean |
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184 | gmake |
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185 | |
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186 | gmake will create tmp and bin directories in your $G4TMP and $G4BIN directories. |
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187 | The executable, named exRDM, will be in $G4BIN/$G4SYSTEM/ directory. |
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188 | |
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189 | iii) Run the executable: while in the exrdm directory do |
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190 | |
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191 | $G4BIN/$G4SYSTEM/exRDM exrdm.in |
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192 | |
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193 | If all goes well, the execution shall be terminated in a few seconds. If G4ANALYSIS_USE_ROOT is |
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194 | defined, there will be a proton.root file in the current directory. |
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195 | |
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196 | One can use ROOT to exam the file. |
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197 | |
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198 | 8. FURTHER EXAMPLES: |
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199 | |
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200 | There are a number of g4mac files in the ./macros subdirectory, to show the features of the G4RadioactiveDecay |
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201 | process. Most of them will lead to the creation of an aida file in the same name of the micro file, which can |
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202 | be examed and analysed with an analysis tool such as ROOT. |
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203 | |
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204 | vrml.mac: to visulise the geometry and the incident of one 100 MeV Cf240 isotope and its decay. A vrml |
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205 | file (g4_xx.vrml) is created at the end. If a default vrml viewer has been set, one shall |
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206 | see the geometru and track displayed automatically. |
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207 | |
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208 | u238c.mac: shows the decays of the U238 chain in analogue MC mode. |
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209 | |
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210 | th234c-b.mac: shows the decays of Th234 in variance reduction MC mode. All its secondaies in along the |
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211 | decay chains are generated. The default source profile and decay biasing schemes are used |
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212 | to determine the decay times and weights of the secondaries. |
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213 | |
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214 | proton-1gev.mac: simulation of 1 GeV protons incident on a lead target. The decays of the radio-siotopes |
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215 | created in the proton-lead interactions are simulated with RadioactiveDecay in analogue |
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216 | MC mode. |
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217 | |
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218 | proton-b.mac: same as proton-1geV.mac, but the decays of the radio-siotopes created in the proton-lead |
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219 | interactions are simulated with RadioactiveDecay in variance reduction MC mode. The isotopes |
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220 | and those along the decay chains are forced to decay in the time windows specified by the |
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221 | user in file measures.data, and the weights of the decay products are determined by the |
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222 | beam profile as defined in the beam.data file and their decay times. |
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223 | |
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224 | one-iso.mac: simple macro file to show how to simulate the decay of a specific radio-isotope. User can |
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225 | edit it to simulate which ever isotope he/she likes to try. |
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226 | |
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227 | neutron.mac: macrofile to show the incident of low energy neutrons on an user specified NaI target and |
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228 | the decays of the induced radio-isotopes. This shows how to define a new material in exrdm. |
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229 | |
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230 | ne24.mac: this shows the decays of Ne-24 to Na-24 in variance reduction MC mode. Further decays of Na-24 |
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231 | are not simulated by applying the nucleuslimits in RadioactiveDecay. Two runs are carried out. |
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232 | One with the bracjing ratio biasing applied and one without. |
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233 | |
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234 | multiple-source.mac: to show the decays of different isotopes uniformly distributed through the target |
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235 | volume in a single run. |
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236 | |
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237 | isotopes.mac: to show the decays of a number of different isotopes in a single macro file. |
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238 | |
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239 | |
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240 | f24.mac: to show the different treatments one can apply to the decays of F24. i) the complete decay chain |
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241 | from F24 to Mg24, in analogue mode; ii) the complete chain, but in variance reduction mode; |
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242 | iii) restrict to the decay of F24 only in analogue mode; iv) restrict to the decay of F24 only but |
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243 | in variance reduction mode. |
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244 | |
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245 | as74.mac: The decays of As74 which has a rather complicated decay scheme. i) in analogue MC mode; ii) in |
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246 | variance reduction MC mode. |
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247 | |
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248 | test.mac: macro used to check if the right physics processes are assigned to different particles. |
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249 | |
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