| Geant4 Cross Reference |
1 ------------------------------------------------------------------- 2 3 ========================================================= 4 Geant4 - an Object-Oriented Toolkit for Simulation in HEP 5 ========================================================= 6 7 Example B1 8 ----------- 9 10 This example demonstrates a very simple application where an energy 11 deposit is accounted in user actions and their associated objects 12 and a dose in a selected volume is calculated. 13 14 15 1- GEOMETRY DEFINITION 16 17 The geometry is constructed in the B1::DetectorConstruction class. 18 The setup consists of a an envelope of box shape containing two 19 volumes: a spherical cone and a trapezoid. 20 21 In this example we use some common materials materials for medical 22 applications. The envelope is made of water and the two inner volumes 23 are made from tissue and bone materials. 24 The materials are created with the help of the G4NistManager class, 25 which allows to build a material from the NIST database using their 26 names. All available materials can be found in the Geant4 User's Guide 27 for Application Developers, Appendix 10: Geant4 Materials Database. 28 29 2- PHYSICS LIST 30 31 The particle's type and the physic processes which will be available 32 in this example are set in the QBBC physics list. This physics list 33 requires data files for electromagnetic and hadronic processes. 34 See more on installation of the datasets in Geant4 Installation Guide, 35 Chapter 3.3: Note On Geant4 Datasets: 36 http://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides 37 /InstallationGuide/html/ch03s03.html 38 The following datasets: G4LEDATA, G4LEVELGAMMADATA, G4NEUTRONXSDATA, 39 G4SAIDXSDATA and G4ENSDFSTATEDATA are mandatory for this example. 40 41 In addition the build-in interactive command: 42 /process/(in)activate processName 43 allows to activate/inactivate the processes one by one. 44 45 3- ACTION INITALIZATION 46 47 A newly introduced class, B1::ActionInitialization, instantiates and registers 48 to Geant4 kernel all user action classes. 49 50 While in sequential mode the action classes are instatiated just once, 51 via invoking the method: 52 B1::ActionInitialization::Build() 53 in multi-threading mode the same method is invoked for each thread worker 54 and so all user action classes are defined thread-local. 55 56 A run action class is instantiated both thread-local 57 and global that's why its instance is created also in the method 58 B1::ActionInitialization::BuildForMaster() 59 which is invoked only in multi-threading mode. 60 61 4- PRIMARY GENERATOR 62 63 The primary generator is defined in the B1::PrimaryGeneratorAction class. 64 The default kinematics is a 6 MeV gamma, randomly distributed in front 65 of the envelope across 80% of the transverse (X,Y) envelope size. 66 This default setting can be changed via the Geant4 built-in commands 67 of the G4ParticleGun class. 68 69 5- DETECTOR RESPONSE 70 71 This example demonstrates a simple scoring implemented directly 72 in the user action classes. Alternative ways of scoring via Geant4 classes 73 can be found in the other examples. 74 75 The energy deposited is collected step by step for a selected volume 76 in B1::SteppingAction and accumulated event by event in B1::EventAction. 77 78 At end of event, the value acummulated in B1::EventAction is added in B1::RunAction 79 and summed over the whole run (see B1::EventAction::EndOfevent()). 80 81 Total dose deposited is computed at B1::RunAction::EndOfRunAction(), 82 and printed together with informations about the primary particle. 83 In multi-threading mode the energy accumulated in G4Accumulable objects per 84 workers is merged to the master in B1::RunAction::EndOfRunAction() and the final 85 result is printed on the screen. 86 87 G4Parameter<G4double> type instead of G4double type is used for the B1::RunAction 88 data members in order to facilitate merging of the values accumulated on workers 89 to the master. Currently the accumulables have to be registered to G4AccumulablesManager 90 and G4AccumulablesManager::Merge() has to be called from the users code. This is planned 91 to be further simplified with a closer integration of G4Accumulable classes in 92 the Geant4 kernel next year. 93 94 An example of creating and computing new units (e.g., dose) is also shown 95 in the class constructor. 96 97 The following paragraphs are common to all basic examples 98 99 A- VISUALISATION 100 101 The visualization manager is set via the G4VisExecutive class 102 in the main() function in exampleB1.cc. 103 The initialisation of the drawing is done via a set of /vis/ commands 104 in the macro vis.mac. This macro is automatically read from 105 the main function when the example is used in interactive running mode. 106 107 By default, vis.mac opens an OpenGL viewer (/vis/open OGL). 108 The user can change the initial viewer by commenting out this line 109 and instead uncommenting one of the other /vis/open statements, such as 110 HepRepFile or DAWNFILE (which produce files that can be viewed with the 111 HepRApp and DAWN viewers, respectively). Note that one can always 112 open new viewers at any time from the command line. For example, if 113 you already have a view in, say, an OpenGL window with a name 114 "viewer-0", then 115 /vis/open DAWNFILE 116 then to get the same view 117 /vis/viewer/copyView viewer-0 118 or to get the same view *plus* scene-modifications 119 /vis/viewer/set/all viewer-0 120 then to see the result 121 /vis/viewer/flush 122 123 The DAWNFILE, HepRepFile drivers are always available 124 (since they require no external libraries), but the OGL driver requires 125 that the Geant4 libraries have been built with the OpenGL option. 126 127 From Release 9.6 the vis.mac macro in example B1 has additional commands 128 that demonstrate additional functionality of the vis system, such as 129 displaying text, axes, scales, date, logo and shows how to change 130 viewpoint and style. Consider copying these to other examples or 131 your application. To see even more commands use help or 132 ls or browse the available UI commands in the Application 133 Developers Guide, Section 7.1. 134 135 For more information on visualization, including information on how to 136 install and run DAWN, OpenGL and HepRApp, see the visualization tutorials, 137 for example, 138 http://geant4.slac.stanford.edu/Presentations/vis/G4[VIS]Tutorial/G4[VIS]Tutorial.html 139 (where [VIS] can be replaced by DAWN, OpenGL and HepRApp) 140 141 The tracks are automatically drawn at the end of each event, accumulated 142 for all events and erased at the beginning of the next run. 143 144 B- USER INTERFACES 145 146 The user command interface is set via the G4UIExecutive class 147 in the main() function in exampleB1.cc 148 The selection of the user command interface is then done automatically 149 according to the Geant4 configuration or it can be done explicitly via 150 the third argument of the G4UIExecutive constructor (see exampleB4a.cc). 151 152 C- HOW TO RUN 153 154 - Execute exampleB1 in the 'interactive mode' with visualization: 155 % ./exampleB1 156 and type in the commands from run1.mac line by line: 157 Idle> /control/verbose 2 158 Idle> /tracking/verbose 1 159 Idle> /run/beamOn 10 160 Idle> ... 161 Idle> exit 162 or 163 Idle> /control/execute run1.mac 164 .... 165 Idle> exit 166 167 - Execute exampleB1 in the 'batch' mode from macro files 168 (without visualization) 169 % ./exampleB1 run2.mac 170 % ./exampleB1 exampleB1.in > exampleB1.out 171 172