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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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