$Id: README,v 1.1 2006/05/09 16:22:19 maire Exp $ ------------------------------------------------------------------- ========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= TestEm17 -------- This example is intended to check implementation of the processes of muon interactions: ionization, direct (e+,e-) production, bremsstrahlung, mu-nuclear interaction. It allows to compute differential cross sections (as function of the energy tranfered to secondaries), total cross sections and to compare with analytic calculations. 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 m of Iron) is constructed in DetectorConstruction, but the above parameters can be changed interactively via the commands defined in DetectorMessenger. 2- PHYSICS LIST The physics list contains only electromagnetic processes for muon, adding G4MuNuclearInteraction and seting of upper energy range limit to 1000 PeV). Standard (default) and g4v52 (frozen at the release Geant4 v.5.2) physics can be choosen. 3- AN EVENT : THE PRIMARY GENERATOR The primary kinematic consists of a single particle starting at the edge of the box. The type of the particle and its energy are set in PrimaryGeneratorAction (mu+ 10 TeV), and can be changed via the G4 build-in commands of ParticleGun class (see the macros provided with this example). 4- PHYSICS The incident particle is a muon. During the tracking, secondary particles are killed. The number of interactions are plotted as a function of the energy transfered to the secondaries. The total number of interactions is recorded, and the total crossSection computed from this. At EndOfRun, the above results are compared with analytic calculations. The functions which compute the theoritical crossSections have been provided by the G4 MEPhI group, and grouped in MuCrossSection class. 5- HISTOGRAMS The test contains 4 built-in 1D histograms, which are managed by the HistoManager class and its Messenger. 1 Monte-Carlo relative transferred energy distribution histo (log10(eps/Emu kin) for knock-on electrons (ionization) 2 -"- direct (e+,e-) pair production 3 -"- bremsstrahlung 4 -"- nuclear interaction The histos can be activated individually with the command : /testem/histo/setHisto id nbBins valMin valMax : min and max values of log10(eps/Emu kin). At EndOfRun the corresponding histos for analytic calculations are automatically created anf filled (histo 6 to 9), and the comparison (G4 divided by theory) is done in histos 11 to 14. One can control the name and the type of the histograms file with the commands: /testem/histo/setFileName name (default testem17) /testem/histo/setFileType name (default hbook) 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/TestEm17 % gmake execute TestEm17 in 'batch' mode from macro files : % TestEm17 allproc.mac execute TestEm17 in 'interactive mode' with visualization : % TestEm17 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