$Id: README,v 1.4 2007/11/13 14:13:31 maire Exp $ ------------------------------------------------------------------- ========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= TestEm15 -------- How to compute and plot the final state of Multiple Scattering considered as an isolated process. The method is exposed below : see item Physics. 1- GEOMETRY DEFINITION It is a single box representing a 'semi infinite' homogeneous medium. Two parameters define the geometry : - the material of the box, - the (full) size of the box. The default geometry (100 m of water) 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 the standard electromagnetic processes. In order not to introduce 'articicial' constraints on the step size, there is no limitation from the maximum energy lost per step. 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 (1 MeV electron), and can be changed via the G4 build-in commands of ParticleGun class (see the macros provided with this example). 4- PHYSICS All discrete processes are inactivated (see provided macros), so that Multiple Scattering is 'forced' to determine the first step of the primary particle. The step size and the final state are computed and plotted. Then the event is immediately killed. The result is compared with the 'input' data, i.e. with the cross sections stored in the PhysicsTables and used by Geant4. The stepMax command provides an additionnal control of the step size of the multiple scattering. 5- HISTOGRAMS The test contains 9 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, etc..) (see the macros xxxx.mac). 1 Multiple Scattering. True step length 2 Multiple Scattering. Geom step length 3 Multiple Scattering. Ratio geomSl/trueSl 4 Multiple Scattering. Lateral displacement: radius 5 Multiple Scattering. Lateral displac: psi_space 6 Multiple Scattering. Angular distrib: theta_plane 7 Multiple Scattering. Phi-position angle 8 Multiple Scattering. Phi-direction angle 9 Multiple Scattering. Correlation: cos(phiPos-phiDir) See below the note on histogram tools. One can control the name and the type of the histograms file with the commands: /testem/histo/setFileName name (default testem15) /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 testem15) 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/TestEm15 % gmake execute TestEm15 in 'batch' mode from macro files : % TestEm15 compt.mac execute TestEm15 in 'interactive mode' with visualization : % TestEm15 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