[807] | 1 | |
---|
| 2 | ========================================================= |
---|
| 3 | Geant4 - an Object-Oriented Toolkit for Simulation in HEP |
---|
| 4 | ========================================================= |
---|
| 5 | |
---|
| 6 | Extended Example for G4RadioactiveDecay |
---|
| 7 | -------------------- |
---|
| 8 | |
---|
[1230] | 9 | The exRDM is created to show how to use the G4RadioactiveDecay process to simulate the decays of |
---|
| 10 | radioactive isotopes as well as the induced radioactivity resulted from nuclear interactions. |
---|
[807] | 11 | |
---|
[1230] | 12 | In this example a simple geometry consists of a cylindric target placed in the centre of a tube detector |
---|
| 13 | is constructed. Various primary event generation and tallying options are available. Further documentations |
---|
| 14 | are available at |
---|
| 15 | |
---|
[807] | 16 | http://reat.space.qinetiq.com/septimess/exrdm |
---|
| 17 | |
---|
| 18 | 1. GEOMETRY |
---|
| 19 | |
---|
| 20 | Material: There are 7 pre-defined materials: |
---|
| 21 | "Vacuum" "Air" "Silicon" "Aluminium" "Lead" "Germanium" and "CsI" |
---|
| 22 | |
---|
| 23 | User can add a new material at the "PreIni" state, using the command |
---|
| 24 | /geometry/material/add |
---|
| 25 | |
---|
| 26 | For the geometry, the world is filled with "Air" and there are two components in it |
---|
| 27 | |
---|
| 28 | - Target: A cylinder placed at the origin along the z-axis. The default size of the cylinder is |
---|
| 29 | 0.5 cm radius and 1 cm in length, and its default material is "CsI". |
---|
| 30 | |
---|
| 31 | - Detector:A tube cerntred at the origin along the z-axis, with inner radius matching the |
---|
| 32 | radius of the target. The default thickness of the tube is 2 cm and it is |
---|
| 33 | 5 cm long. The default material is "Germanium". |
---|
| 34 | |
---|
[1230] | 35 | The user can change the target/detector size and material at the at the "PreIni" state, using the |
---|
| 36 | commands in the directory |
---|
[807] | 37 | |
---|
| 38 | /exrdm/det |
---|
| 39 | |
---|
| 40 | 2. PHYSICS |
---|
| 41 | |
---|
| 42 | The following physics processes are included by default: |
---|
| 43 | |
---|
| 44 | - Standard electromagnetic: |
---|
| 45 | photo-electric effect |
---|
| 46 | Compton scattering |
---|
| 47 | pair production |
---|
| 48 | bremsstrahlung |
---|
| 49 | ionization |
---|
| 50 | multiple scattering |
---|
| 51 | annihilation |
---|
| 52 | |
---|
| 53 | - Decay |
---|
| 54 | |
---|
| 55 | - Radioactive Decay |
---|
| 56 | By default it is applied through out the geometry. The user can limit it to just the target by |
---|
| 57 | commands |
---|
| 58 | |
---|
| 59 | /grdm/noVolumes |
---|
| 60 | /grdm/selectVolume Target |
---|
| 61 | |
---|
| 62 | - Hadronic processes: |
---|
| 63 | Hadronic processes are not invoked by default. They can be activated by the user at the "PreIni" |
---|
[1230] | 64 | state via the command |
---|
[807] | 65 | |
---|
| 66 | /exrdm/phys/SelectPhysics |
---|
| 67 | |
---|
| 68 | The options are: |
---|
| 69 | |
---|
| 70 | "Hadron" - Physicslist comsists of Binary_Cascade, HP_Neutron, QGSP, and LHEP, or |
---|
| 71 | the standdard hadron physics list avaible in the G4 distribution, i.e. |
---|
| 72 | "QGSP_BERT", "QGSP_BIC", "QGSP_HP", "LHEP_BERT", "LHEP_BERT_HP", "LHEP_BIC", |
---|
| 73 | "LHEP_BIC_HP". |
---|
| 74 | |
---|
| 75 | 3. EVENT: |
---|
| 76 | |
---|
| 77 | The event generator is based on the G4GeneralParticleSource (GPS) which allows the user to |
---|
| 78 | control all aspects of the initial states of the events. In this example, however, only simple features |
---|
| 79 | of the GPS are employed to generate the incident beam or the initial radio-isotopes. By default the |
---|
| 80 | incident particle is travelling along the + z-axis and the incident position is at the -Z end |
---|
| 81 | of the geometry. |
---|
| 82 | |
---|
| 83 | 4. DETECTOR RESPONSE: |
---|
| 84 | |
---|
[1230] | 85 | No Geant4 HITS and SD are defined in this example. If the variable "G4ANALYSIS_USE" is defined, all |
---|
| 86 | the relevant information of the simulation is collected at the "UserSteppingAction" stage. These |
---|
| 87 | include: |
---|
[807] | 88 | |
---|
| 89 | - Emission particles in the RadioactiveDecay process: |
---|
| 90 | particle PDGcode, |
---|
| 91 | partilce kinetic energy, |
---|
| 92 | particle creation time, |
---|
| 93 | particle weight. |
---|
| 94 | |
---|
| 95 | Note: the residual nuclei is not considered as an emitted particle. |
---|
| 96 | |
---|
| 97 | - Radio-Isotopes. All the radioactive isotopes produced in the simulation: |
---|
| 98 | isotope PDGcode, |
---|
| 99 | isotope creation time, |
---|
| 100 | isotope weight. |
---|
| 101 | |
---|
| 102 | - Energy depositions in the target and detector by prodicts of the RadioactiveDecay process: |
---|
| 103 | energy depostion (positive volue for target and negative for detector), |
---|
| 104 | time, |
---|
| 105 | weight. |
---|
| 106 | |
---|
| 107 | 5. VISUALIZATION: |
---|
| 108 | |
---|
| 109 | Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An |
---|
| 110 | example of display the geometry and tracks using VRML is given in the macro file macros/vrml.mac. |
---|
| 111 | |
---|
| 112 | 6. ANALYSIS: |
---|
| 113 | |
---|
[1230] | 114 | This example implements an AIDA-compliant analysis system as well as the ROOT system, for accumulating |
---|
| 115 | and output histograms and ntuples. If the the user has an AIDA-compliant tool such as |
---|
| 116 | AIDAJNI, ANAPHE, OpenScientist or PI installed, the analysis part of this example can |
---|
[807] | 117 | be activated by |
---|
| 118 | |
---|
[1230] | 119 | setenv G4ANALYSIS_USE 1 |
---|
[807] | 120 | |
---|
[1230] | 121 | before building the executable. |
---|
| 122 | |
---|
| 123 | The user can also use the executable with the ROOT system, if it is available. This is done by |
---|
[807] | 124 | |
---|
[1230] | 125 | setenv G4ANALYSIS_USE_ROOT 1 |
---|
[807] | 126 | |
---|
[1230] | 127 | again before the compilation. The AIDA and ROOT systems can be used individually, or in parallel |
---|
| 128 | at the same time! |
---|
[807] | 129 | |
---|
[1230] | 130 | If no analysis system is activated, there is no output file produced apart from the screen dump. |
---|
| 131 | A file called "exrdm.aida" is produced by default for AIDA system and "exrdm.root" if the ROOT |
---|
| 132 | system is selected. |
---|
| 133 | |
---|
| 134 | The user can change the name of this output file with the command |
---|
[807] | 135 | |
---|
| 136 | /histo/fileName new-filename |
---|
| 137 | |
---|
[1230] | 138 | The output AIDA file by default is in xml format. The AIDA system allows the use of other file format |
---|
| 139 | such as "root" and "hbook". User can change the output format to "hbook" or "root" using the command |
---|
| 140 | /histo/fileType.e.g. |
---|
[807] | 141 | |
---|
| 142 | /histo/fileType hbook |
---|
[1230] | 143 | /histo/fileType root |
---|
[807] | 144 | |
---|
[1230] | 145 | When "root" format is selected for the AIDA system, the output AIDA file name is changed to |
---|
| 146 | fileName_aida.root. This is to separate it from the the ROOT system output file fileName.root, in case |
---|
| 147 | both systems are used. |
---|
| 148 | |
---|
| 149 | The output file, in "aida" or "hbook" or "root" format, conatins the 3 ntuples (100,200,300) which have |
---|
| 150 | been described in section 4. In addition, there are 7 histograms in the file: |
---|
[807] | 151 | |
---|
| 152 | histogram 10: The Pulse Height Spectrum (PHS) of the target. |
---|
| 153 | histogram 11: The PHS of the detector. |
---|
| 154 | histogram 12: The combined PHS of the target and detector. |
---|
| 155 | histogram 13: The anti-coincidece PHS of the target. |
---|
| 156 | histogram 14: The anti-coincidece PHS of the detector. |
---|
| 157 | histogram 15: The coincidece PHS between the target and detector. |
---|
| 158 | histogram 16: The emitted particle energy spectrum. |
---|
| 159 | |
---|
| 160 | The binnings of each histogram can be changed with the command |
---|
| 161 | |
---|
| 162 | /histo/setHisto |
---|
| 163 | |
---|
[1230] | 164 | It is assumed the detector and target pulses both have an integration time of 1 microsecond, and the |
---|
| 165 | gate is 2 microsecond for the coincidence spectrum. The target and detctor have a threshold of 10 keV |
---|
| 166 | in the anti-/coincidence modes. |
---|
[807] | 167 | |
---|
| 168 | Histograms 10-15 were derived from the same data stored in ntuple-300(the energy depositions), while |
---|
| 169 | Histogram 16 is obtained with data in ntuple-100 (the emission particles). The user should be able to |
---|
[1230] | 170 | reproduce these histograms, or new histograms, with the ntuple data in an off-line analyis tool. |
---|
[807] | 171 | |
---|
| 172 | 7. GETTING STARTED: |
---|
| 173 | |
---|
| 174 | i) If you have an AIDA-compliant analysis system installed than you shall switch on the analysis part of |
---|
| 175 | example by |
---|
| 176 | |
---|
[1230] | 177 | setenv G4ANALYSIS_USE 1 |
---|
[807] | 178 | |
---|
[1230] | 179 | in addition if you want to add the ROOT link to the ROOT system, do |
---|
[807] | 180 | |
---|
| 181 | setenv G4ANALYSIS_USE_ROOT 1 |
---|
| 182 | |
---|
[1230] | 183 | Otherwise make sure the G4ANALYSIS_USE and G4ANALYSIS_USE_ROOT are not definded |
---|
[807] | 184 | |
---|
[1230] | 185 | unsetenv G4ANALYSIS_USE |
---|
[807] | 186 | unsetenv G4ANALYSIS_USE_ROOT |
---|
| 187 | |
---|
| 188 | ii) Build the exRDM executable: |
---|
| 189 | |
---|
| 190 | cd to exrdm |
---|
| 191 | gmake clean |
---|
| 192 | gmake |
---|
| 193 | |
---|
[1230] | 194 | Depends on the setup, gmake will create tmp and bin directories in your $G4TMP and $G4BIN directories. |
---|
[807] | 195 | The executable, named exRDM, will be in $G4BIN/$G4SYSTEM/ directory. |
---|
| 196 | |
---|
| 197 | iii) Run the executable: while in the exrdm directory do |
---|
| 198 | |
---|
| 199 | $G4BIN/$G4SYSTEM/exRDM exrdm.in |
---|
| 200 | |
---|
[1230] | 201 | If all goes well, the execution shall be terminated in a few seconds. If G4ANALYSIS_USE is defined, one |
---|
| 202 | should see a "proton.aida" file created. If G4ANALYSIS_USE_ROOT is defined, there will be |
---|
| 203 | a proton.root file in the same directory. |
---|
[807] | 204 | |
---|
| 205 | 8. FURTHER EXAMPLES: |
---|
| 206 | |
---|
[1230] | 207 | There are a number of g4mac files in the ./macros subdirectory, to show the features of the |
---|
| 208 | G4RadioactiveDecay process. Most of them will lead to the creation of an aida file in the same name |
---|
| 209 | of the micro file, which can be examed and analysed with an analysis tool such as OpenScientist ,or JAS3. |
---|
[807] | 210 | |
---|
| 211 | vrml.mac: to visulise the geometry and the incident of one 100 MeV Cf240 isotope and its decay. A vrml |
---|
| 212 | file (g4_xx.vrml) is created at the end. If a default vrml viewer has been set, one shall |
---|
| 213 | see the geometru and track displayed automatically. |
---|
| 214 | |
---|
| 215 | u238c.mac: shows the decays of the U238 chain in analogue MC mode. |
---|
| 216 | |
---|
| 217 | th234c-b.mac: shows the decays of Th234 in variance reduction MC mode. All its secondaies in along the |
---|
| 218 | decay chains are generated. The default source profile and decay biasing schemes are used |
---|
| 219 | to determine the decay times and weights of the secondaries. |
---|
| 220 | |
---|
| 221 | proton-1gev.mac: simulation of 1 GeV protons incident on a lead target. The decays of the radio-siotopes |
---|
| 222 | created in the proton-lead interactions are simulated with RadioactiveDecay in analogue |
---|
| 223 | MC mode. |
---|
| 224 | |
---|
| 225 | proton-b.mac: same as proton-1geV.mac, but the decays of the radio-siotopes created in the proton-lead |
---|
| 226 | interactions are simulated with RadioactiveDecay in variance reduction MC mode. The isotopes |
---|
| 227 | and those along the decay chains are forced to decay in the time windows specified by the |
---|
| 228 | user in file measures.data, and the weights of the decay products are determined by the |
---|
| 229 | beam profile as defined in the beam.data file and their decay times. |
---|
| 230 | |
---|
| 231 | one-iso.mac: simple macro file to show how to simulate the decay of a specific radio-isotope. User can |
---|
| 232 | edit it to simulate which ever isotope he/she likes to try. |
---|
| 233 | |
---|
| 234 | neutron.mac: macrofile to show the incident of low energy neutrons on an user specified NaI target and |
---|
| 235 | the decays of the induced radio-isotopes. This shows how to define a new material in exrdm. |
---|
| 236 | |
---|
| 237 | ne24.mac: this shows the decays of Ne-24 to Na-24 in variance reduction MC mode. Further decays of Na-24 |
---|
| 238 | are not simulated by applying the nucleuslimits in RadioactiveDecay. Two runs are carried out. |
---|
| 239 | One with the bracjing ratio biasing applied and one without. |
---|
| 240 | |
---|
| 241 | multiple-source.mac: to show the decays of different isotopes uniformly distributed through the target |
---|
| 242 | volume in a single run. |
---|
| 243 | |
---|
| 244 | isotopes.mac: to show the decays of a number of different isotopes in a single macro file. |
---|
| 245 | |
---|
| 246 | |
---|
| 247 | f24.mac: to show the different treatments one can apply to the decays of F24. i) the complete decay chain |
---|
| 248 | from F24 to Mg24, in analogue mode; ii) the complete chain, but in variance reduction mode; |
---|
| 249 | iii) restrict to the decay of F24 only in analogue mode; iv) restrict to the decay of F24 only but |
---|
| 250 | in variance reduction mode. |
---|
| 251 | |
---|
| 252 | as74.mac: The decays of As74 which has a rather complicated decay scheme. i) in analogue MC mode; ii) in |
---|
| 253 | variance reduction MC mode. |
---|
| 254 | |
---|
| 255 | test.mac: macro used to check if the right physics processes are assigned to different particles. |
---|
| 256 | |
---|