$Id: README,v 1.21 2007/11/28 12:37:56 maire Exp $ ----------------------------------------------------- ========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= TestEm5 ------- How to study the transmission, absorption and reflexion of particles through a single, thin or thick, layer of material. In perticular, the effects of the multiple scattering can be ploted. 1- GEOMETRY DEFINITION The "absorber" is a box made of a given material. Three parameters define the absorber : - the material of the absorber, - the thickness of an absorber, - the transverse size of the absorber (the input face is a square). A volume "World" contains the "absorber". In addition a transverse uniform magnetic field can be applied. The default geometry is constructed in DetectorConstruction class, but all the parameters can be changed via commands defined in the DetectorMessenger class. The parameters of the "World" can be changed, too. 2- PHYSICS LIST The following EM physics lists are available in this example: - "standard" standard EM physics (default) - "livermore" low-energy EM physics using Livermore data - "penelope" low-energy EM physics implementing Penelope models - "standardSS" standard EM physics with single Coulomb scattering instead of multiple scattering Alternatively, the user may use predefined Geant4 builders: - "emstandard" G4EmStandardPhysics builder - "emstandard_opt1" G4EmStandardPhysics_option1 builder - "emstandard_opt2" G4EmStandardPhysics_option2 builder See geant4/source/physics_lists/History for details 3- AN EVENT : THE PRIMARY GENERATOR The primary kinematic consists of a single particle which hits the absorber perpendicular to the input face. The type of the particle and its energy are set in the PrimaryGeneratorAction class, and can be changed via the G4 build-in commands of ParticleGun class (see the macros provided with this example). In addition one can choose randomly the impact point of the incident particle. The interactive command is built in PrimaryGeneratorMessenger class. 4- VISUALIZATION The Visualization Manager is set in the main(). The initialisation of the drawing is done via the commands in vis.mac In interactive session: PreInit or Idle > /control/execute vis.mac The example has a default view which is a longitudinal view of the detector. The tracks are drawn at the end of event, and erased at the end of run. Optionaly one can choose to draw all particles, only the charged, or none. This command is defined in EventActionMessenger class. 5- TRACKING During the tracking, one can keep or not the secondaries : see StackingAction class and its Messenger. One can also limit 'by hand' the step lenght of the particle. As an example, this limitation is implemented as a 'full' process : see StepMax class and its Messenger. The 'StepMax process' is registered in the Physics List. 6- DETECTOR RESPONSE At the end of a run, from the histogram(s), one can study different physics quantities such as : - energy deposit in the absorber, - energy spectrum of secondaries at creation, - energy spectrum and angle distribution of particles at exit, - transmission and backscattering coefficients, - ... 7- List of the built-in histograms ---------------------------------- The test contains more than 20 built-in 1D histograms, which are managed by the HistoManager class and its Messenger. The histos can be individually activated with the command : /testem/histo/setHisto id nbBins valMin valMax unit where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..) (see the macros xxxx.mac). 1 "energy deposit in absorber" 2 "energy of charged secondaries at creation" 3 "energy of gammas at creation (log10(Ekin/MeV))" 4 "x_vertex of charged secondaries (all)" 5 "x_vertex of charged secondaries (not absorbed)" 10 "(transmit, charged) : kinetic energy at exit" 11 "(transmit, charged) : ener fluence: dE(MeV)/dOmega" 12 "(transmit, charged) : space angle dN/dOmega" 13 "(transmit, charged) : projected angle at exit" 14 "(transmit, charged) : projected position at exit" 15 "(transmit, charged) : radius at exit" 20 "(transmit, neutral) : kinetic energy at exit" 21 "(transmit, neutral) : ener fluence: dE(MeV)/dOmega" 22 "(transmit, neutral) : space angle dN/dOmega" 23 "(transmit, neutral) : projected angle at exit" 30 "(reflect , charged) : kinetic energy at exit" 31 "(reflect , charged) : ener fluence: dE(MeV)/dOmega" 32 "(reflect , charged) : space angle dN/dOmega" 33 "(reflect , charged) : projected angle at exit" 40 "(reflect , neutral) : kinetic energy at exit" 41 "(reflect , neutral) : ener fluence: dE(MeV)/dOmega" 42 "(reflect , neutral) : space angle dN/dOmega" 43 "(reflect , neutral) : projected angle at exit" The histograms can be viewed using PAW. See below the note on ANAPHE+AIDA. One can control the name of the histograms file with the command: /testem/histo/setFileName name (default testem5.hbook) It is also possible to print selected histograms on an ascii file: /testem/histo/printHisto id All selected histos will be written on a file name.ascii (default testem5) Note that, by default, histograms are disabled. To activate them, uncomment the flag G4ANALYSIS_USE in GNUmakefile. 8- GEANT4/GEANT3/DATA COMPARISON A Geant4/Geant3/exp. data comparison is given here for a few cases. These cases can be classified as follow: - e-/e+ incident particles versus protons and others. - 3 energy regimes: low: < 1MeV; medium: 1MeV -> few 10MeV; high: > 100MeV We indicate here the corresponding macros. | low energy | medium energy | high energy -------------------------------------------------------- | acosta.mac | | e-+ | berger.mac | hanson.mac | | hunger.mac | kulchi.mac | | tavola.mac | | -------------------------------------------------------- others| bichsel.mac | vincour.mac | shen1.mac shen2.mac | | gottsch.mac | tramu.mac -------------------------------------------------------- The relevant part of the GEANT3 code is in the subdirectory geant3 together with the xxxx.dat input files. 9- HOW TO START ? - compile and link to generate an executable % cd TestEm5 % gmake - execute TestEm5 in 'batch' mode from macro files e.g. % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 myMacro.mac - execute TestEm5 in 'interactive' mode with visualization e.g. % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 Then type your commands, for instance : Idle> control/execute vis.mac Idle> run/beamOn 5 .... 10- USING HISTOGRAMS Note that, by default, histograms are disabled. To activate them, uncomment the flag G4ANALYSIS_USE in GNUmakefile. Before compilation of the example it is optimal to clean up old files: gmake histclean gmake To use histograms, at least one of the AIDA implementations should be available (see http://aida.freehep.org). 8a - PI A package including AIDA and extended interfaces also using Python is PI, available from: http://cern.ch/pi Once installed PI or PI-Lite in a specified local area $MYPY, it is required to add the installation path to $PATH, i.e. for example, for release 1.2.1 of PI: setenv PATH ${PATH}:$MYPI/1.2.1/app/releases/PI/PI_1_2_1/rh73_gcc32/bin CERN users can use the PATH to the LCG area on AFS. Before running the example the command should be issued: eval `aida-config --runtime csh` 8b - OpenScientist OpenScientist is available at http://OpenScientist.lal.in2p3.fr. You have to "setup" the OpenScientist AIDA implementation before compiling (then with G4ANALYSIS_USE set) and running your Geant4 application. On UNIX you setup, with a csh flavoured shell : csh> source </aida-setup.csh or with a sh flavoured shell : sh> . </aida-setup.sh On Windows : DOS> call </aida-setup.bat You can use various file formats for writing (AIDA-XML, hbook, root). These formats are readable by the Lab onx interactive program or the OpenPAW application. See the web pages. With OpenPAW, on a run.hbook file, one can view the histograms with something like : OS> opaw opaw> h/file 1 run.hbook ( or opaw> h/file 1 run.aida or run.root) opaw> zone 2 2 opaw> h/plot 1 opaw> h/plot 2