$Id: README,v 1.2 2007/11/13 16:43:59 maire Exp $ ------------------------------------------------------------------- ========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= TestEm18 -------- This example allows to study the energy lost by a charged particle in a single layer, due to ionization and bremsstrahlung. Results are compared to 'reference' values. 1- GEOMETRY DEFINITION It is a single box of homogeneous medium. Two parameters define the geometry : - the material of the box, - the (full) size of the box. The default geometry (1 cm of water) is constructed in DetectorConstruction, but the above parameters can be changed interactively via the commands defined in DetectorMessenger. 2- PHYSICS The physics list contains the 'standard' electromagnetic processes. However the MultipleScattering is not registered, in order to focuse on fluctuations due to energy loss alone. 3- BEAM The primary kinematic is a single particle starting at the edge of the box. The type of the particle and its energy are set in PrimaryGeneratorAction (e- 10 MeV), and can be changed via the G4 build-in commands of ParticleGun class. 4- RUN During the tracking of the incident particle, the secondary particles are immediately killed, after that their energy has been registered (see StackingAction). Therefore, we study here the total energy lost by the incident particle, not the energy deposited in a layer of finite thickness. At EndOfRun, the above results are compared with 'reference' values, i.e. the values read from EnergyLoss tables. 5- HISTOGRAMS The test contains 6 built-in 1D histograms, which are managed by the HistoManager class and its Messenger. 1 continuous energy loss along primary track 2 energy from secondaries 3 total energy lost by primary track (1+2) 4 energy spectrum of e-+ 5 energy spectrum of gamma 6 step size of primary track The histos can be activated individually with the command : /testem/histo/setHisto id nbBins valMin valMax unit where 'unit' is the desired unit for the histo (MeV or KeV, cm or mm, etc..) One can control the name and the type of the histograms file with the commands: /testem/histo/setFileName name (default testem18) /testem/histo/setFileType name (default 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 testem18) Note that, by default, histograms are disabled. To activate them, uncomment the flag G4ANALYSIS_USE in GNUmakefile. 6- VISUALIZATION The Visualization Manager is set in the main(). The initialisation of the drawing is done via the commands /vis/... in the macro vis.mac. To get visualisation: > /control/execute vis.mac The detector has a default view which is a longitudinal view of the box. The tracks are drawn at the end of event, and erased at the end of run. 7- HOW TO START ? compile and link to generate an executable % cd geant4/examples/extended/electromagnetic/TestEm18 % gmake execute TestEm18 in 'batch' mode from macro files : % TestEm18 electron.mac.mac execute TestEm18 in 'interactive mode' with visualization : % TestEm18 Idle> control/execute vis.mac .... Idle> type your commands .... Idle> exit 8- USING HISTOGRAMS By default the histograms are not activated. To activate histograms the environment variable G4ANALYSIS_USE should be defined. For instance 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