========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= Extended Example for G4RadioactiveDecay -------------------- The exRDM is created to show how to use the G4RadioactiveDecay process to simulate the decays of radioactive isotopes as well as the induced radioactivity resulted from nuclear interactions. In this example a simple geometry consists of a cylindric target placed in the centre of a tube detector is constructed. Various primary event generation and tallying options are available. Further documentations are available at http://reat.space.qinetiq.com/septimess/exrdm 1. GEOMETRY Material: There are 7 pre-defined materials: "Vacuum" "Air" "Silicon" "Aluminium" "Lead" "Germanium" and "CsI" User can add a new material at the "PreIni" state, using the command /geometry/material/add For the geometry, the world is filled with "Air" and there are two components in it - Target: A cylinder placed at the origin along the z-axis. The default size of the cylinder is 0.5 cm radius and 1 cm in length, and its default material is "CsI". - Detector:A tube cerntred at the origin along the z-axis, with inner radius matching the radius of the target. The default thickness of the tube is 2 cm and it is 5 cm long. The default material is "Germanium". The user can change the target/detector size and material at the at the "PreIni" state, using the commands in the directory /exrdm/det 2. PHYSICS The following physics processes are included by default: - Standard electromagnetic: photo-electric effect Compton scattering pair production bremsstrahlung ionization multiple scattering annihilation - Decay - Radioactive Decay By default it is applied through out the geometry. The user can limit it to just the target by commands /grdm/noVolumes /grdm/selectVolume Target - Hadronic processes: Hadronic processes are not invoked by default. They can be activated by the user at the "PreIni" state via the command /exrdm/phys/SelectPhysics The options are: "Hadron" - Physicslist comsists of Binary_Cascade, HP_Neutron, QGSP, and LHEP, or the standdard hadron physics list avaible in the G4 distribution, i.e. "QGSP_BERT", "QGSP_BIC", "QGSP_HP", "LHEP_BERT", "LHEP_BERT_HP", "LHEP_BIC", "LHEP_BIC_HP". 3. EVENT: The event generator is based on the G4GeneralParticleSource (GPS) which allows the user to control all aspects of the initial states of the events. In this example, however, only simple features of the GPS are employed to generate the incident beam or the initial radio-isotopes. By default the incident particle is travelling along the + z-axis and the incident position is at the -Z end of the geometry. 4. DETECTOR RESPONSE: No Geant4 HITS and SD are defined in this example. If the variable "G4ANALYSIS_USE" is defined, all the relevant information of the simulation is collected at the "UserSteppingAction" stage. These include: - Emission particles in the RadioactiveDecay process: particle PDGcode, partilce kinetic energy, particle creation time, particle weight. Note: the residual nuclei is not considered as an emitted particle. - Radio-Isotopes. All the radioactive isotopes produced in the simulation: isotope PDGcode, isotope creation time, isotope weight. - Energy depositions in the target and detector by prodicts of the RadioactiveDecay process: energy depostion (positive volue for target and negative for detector), time, weight. 5. VISUALIZATION: Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An example of display the geometry and tracks using VRML is given in the macro file macros/vrml.mac. 6. ANALYSIS: This example implements an AIDA-compliant analysis system as well as the ROOT system, for accumulating and output histograms and ntuples. If the the user has an AIDA-compliant tool such as AIDAJNI, ANAPHE, OpenScientist or PI installed, the analysis part of this example can be activated by setenv G4ANALYSIS_USE 1 before building the executable. The user can also use the executable with the ROOT system, if it is available. This is done by setenv G4ANALYSIS_USE_ROOT 1 again before the compilation. The AIDA and ROOT systems can be used individually, or in parallel at the same time! If no analysis system is activated, there is no output file produced apart from the screen dump. A file called "exrdm.aida" is produced by default for AIDA system and "exrdm.root" if the ROOT system is selected. The user can change the name of this output file with the command /histo/fileName new-filename The output AIDA file by default is in xml format. The AIDA system allows the use of other file format such as "root" and "hbook". User can change the output format to "hbook" or "root" using the command /histo/fileType.e.g. /histo/fileType hbook /histo/fileType root When "root" format is selected for the AIDA system, the output AIDA file name is changed to fileName_aida.root. This is to separate it from the the ROOT system output file fileName.root, in case both systems are used. The output file, in "aida" or "hbook" or "root" format, conatins the 3 ntuples (100,200,300) which have been described in section 4. In addition, there are 7 histograms in the file: histogram 10: The Pulse Height Spectrum (PHS) of the target. histogram 11: The PHS of the detector. histogram 12: The combined PHS of the target and detector. histogram 13: The anti-coincidece PHS of the target. histogram 14: The anti-coincidece PHS of the detector. histogram 15: The coincidece PHS between the target and detector. histogram 16: The emitted particle energy spectrum. The binnings of each histogram can be changed with the command /histo/setHisto It is assumed the detector and target pulses both have an integration time of 1 microsecond, and the gate is 2 microsecond for the coincidence spectrum. The target and detctor have a threshold of 10 keV in the anti-/coincidence modes. Histograms 10-15 were derived from the same data stored in ntuple-300(the energy depositions), while Histogram 16 is obtained with data in ntuple-100 (the emission particles). The user should be able to reproduce these histograms, or new histograms, with the ntuple data in an off-line analyis tool. 7. GETTING STARTED: i) If you have an AIDA-compliant analysis system installed than you shall switch on the analysis part of example by setenv G4ANALYSIS_USE 1 in addition if you want to add the ROOT link to the ROOT system, do setenv G4ANALYSIS_USE_ROOT 1 Otherwise make sure the G4ANALYSIS_USE and G4ANALYSIS_USE_ROOT are not definded unsetenv G4ANALYSIS_USE unsetenv G4ANALYSIS_USE_ROOT ii) Build the exRDM executable: cd to exrdm gmake clean gmake Depends on the setup, gmake will create tmp and bin directories in your $G4TMP and $G4BIN directories. The executable, named exRDM, will be in $G4BIN/$G4SYSTEM/ directory. iii) Run the executable: while in the exrdm directory do $G4BIN/$G4SYSTEM/exRDM exrdm.in If all goes well, the execution shall be terminated in a few seconds. If G4ANALYSIS_USE is defined, one should see a "proton.aida" file created. If G4ANALYSIS_USE_ROOT is defined, there will be a proton.root file in the same directory. 8. FURTHER EXAMPLES: There are a number of g4mac files in the ./macros subdirectory, to show the features of the G4RadioactiveDecay process. Most of them will lead to the creation of an aida file in the same name of the micro file, which can be examed and analysed with an analysis tool such as OpenScientist ,or JAS3. vrml.mac: to visulise the geometry and the incident of one 100 MeV Cf240 isotope and its decay. A vrml file (g4_xx.vrml) is created at the end. If a default vrml viewer has been set, one shall see the geometru and track displayed automatically. u238c.mac: shows the decays of the U238 chain in analogue MC mode. th234c-b.mac: shows the decays of Th234 in variance reduction MC mode. All its secondaies in along the decay chains are generated. The default source profile and decay biasing schemes are used to determine the decay times and weights of the secondaries. proton-1gev.mac: simulation of 1 GeV protons incident on a lead target. The decays of the radio-siotopes created in the proton-lead interactions are simulated with RadioactiveDecay in analogue MC mode. proton-b.mac: same as proton-1geV.mac, but the decays of the radio-siotopes created in the proton-lead interactions are simulated with RadioactiveDecay in variance reduction MC mode. The isotopes and those along the decay chains are forced to decay in the time windows specified by the user in file measures.data, and the weights of the decay products are determined by the beam profile as defined in the beam.data file and their decay times. one-iso.mac: simple macro file to show how to simulate the decay of a specific radio-isotope. User can edit it to simulate which ever isotope he/she likes to try. neutron.mac: macrofile to show the incident of low energy neutrons on an user specified NaI target and the decays of the induced radio-isotopes. This shows how to define a new material in exrdm. ne24.mac: this shows the decays of Ne-24 to Na-24 in variance reduction MC mode. Further decays of Na-24 are not simulated by applying the nucleuslimits in RadioactiveDecay. Two runs are carried out. One with the bracjing ratio biasing applied and one without. multiple-source.mac: to show the decays of different isotopes uniformly distributed through the target volume in a single run. isotopes.mac: to show the decays of a number of different isotopes in a single macro file. f24.mac: to show the different treatments one can apply to the decays of F24. i) the complete decay chain from F24 to Mg24, in analogue mode; ii) the complete chain, but in variance reduction mode; iii) restrict to the decay of F24 only in analogue mode; iv) restrict to the decay of F24 only but in variance reduction mode. as74.mac: The decays of As74 which has a rather complicated decay scheme. i) in analogue MC mode; ii) in variance reduction MC mode. test.mac: macro used to check if the right physics processes are assigned to different particles.