$Id: README,v 1.22 2007/11/12 15:48:58 maire Exp $ ------------------------------------------------------------------- ========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= TestEm1 ------- How to count processes. How to activate/inactivate processes. How to survey the tracking, in perticular the range of charged particles. How to define a maximum step size. 1 - GEOMETRY DEFINITION It is a simple box which represente an 'semi infinite' homogeneous medium. Two parameters define the geometry : - the material of the box, - the full size of the box. In addition a transverse uniform magnetic field can be applied. The default geometry is constructed in DetectorConstruction class, but all of the above parameters can be changed interactively via the commands defined in the DetectorMessenger class. 2 - PHYSICS LIST The particle list is the one of novice/exampleN03. The physics list contains the 'standard' electromagnetic processes, and decay. Few commands have been added to PhysicsList, in order to set the production threshold for secondaries for gamma and e-/e+. 3 - AN EVENT : THE PRIMARY GENERATOR The primary kinematic consists of a single particle starting at the left face of the box. 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 corresponding interactive command is built in PrimaryGeneratorMessenger. 4 - 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. Optionaly one can choose to draw all particles, only the charged, or none. This command is defined in EventActionMessenger class. 5 - PHYSICS SURVEY The particle's type and the physic processes which will be available in this example are set in PhysicsList class. A set of macros defining various run conditions are provided. The processes are actived/inactived together with differents cuts, in order to survey the processes one by one. The number of produced secondaries are counted, the number of steps, and the number of process calls responsible of the step. 6 - HOW TO START ? - compile and link to generate an executable % cd geant4/examples/extended/electromagnetic/TestEm1 % gmake - execute TestEm1 in 'batch' mode from macro files % TestEm1 run10.mac - execute TestEm1 in 'interactive mode' with visualization % TestEm1 .... Idle> type your commands .... Idle> exit 7 - TRACKING : StepMax In order to control the accuracy of the deposition, the user can limit 'by hand' the maximum step size of charged particles. 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. 8 - HISTOGRAMS Testem1 produces several histo which are saved as testem1.hbook by default. Content of these histo: 1 : track length of primary particle 2 : number of steps primary particle 3 : step size of primary particle The histograms 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..) One can control the name of the histograms file with the command: /testem/histo/setFileName name (default testem1) It is possible to choose the format of the histogram file (hbook, root, XML) with the command /testem/histo/setFileType (hbook by default) 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 testem1) 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 9 - USING HISTOGRAMS To use histograms, at least one of the AIDA implementations should be available (see http://aida.freehep.org). 9a - 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` 9b - 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