$Id: README,v 1.28 2010/02/22 15:41:29 maire Exp $ ------------------------------------------------------------------- ========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= TestEm2 ------- How to do shower profiles in an homogenous medium, with virtual voxelisation. 1- GEOMETRY DEFINITION The geometry consists of a cylinder of homegenous material. The default geometry is constructed in DetectorConstruction class, but all of the above parameters can be modified interactively via the commands defined in the DetectorMessenger class. Material can be choosen: Air Water lAr Al Fe BGO PbWO4 Pb. eg: /testem/det/setMat PbWO4 The cylinder is virtually sliced longitudinaly (slice) and radialy (ring). The size of the slices and rings are expressed in radiation length units and can be changed. eg: /testem/det/setLbin 20 1. ---> 20 slices of 1. radl /testem/det/setRbin 5 0.25 ---> 5 rings of 0.25 radl /testem/det/update ---> rebuild the geometry (MaxBin = 500 in both directions) An uniform magnetic field along the cylinder axis can be set. eg: /testem/det/setField 5 tesla 2- PHYSICS LISTS Physics lists can be local (eg. in this example) or from G4 kernel physics_lists subdirectory. Local physics lists: - "local" standard EM physics with current 'best' options setting. these options are explicited in PhysListEmStandard From geant4/source/physics_lists/builders: - "emstandard_opt0" recommended standard EM physics for LHC - "emstandard_opt1" best CPU performance standard physics for LHC - "emstandard_opt2" - "emstandard_opt3" best current advanced EM options. analog to "local" above Physics lists and options can be (re)set with UI commands Please, notice that options set through G4EmProcessOPtions are global, eg for all particle types. In G4 builders, it is shown how to set options per particle type. 3- AN EVENT : THE PRIMARY GENERATOR The primary kinematic consists of a single particle which hits the cylinder perpendicular to the input face. The type of the particle and its energy are set in the PrimaryGeneratorAction class, and can changed via the G4 build-in commands of ParticleGun class (see the macros provided with this example). A RUN is a set of events. 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. In interactive session: PreInit or Idle > /control/execute vis.mac The detector has a default view which is a longitudinal view of the cylinder. 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 one, or none. This command is defined in EventActionMessenger class. 5- PHYSICS DEMO The particle's type and the physic processes which will be available in this example are set in PhysicsList class. In addition a build-in interactive command (/process/inactivate proname) allows to activate/inactivate the processes one by one. The threshold for producing secondaries can be changed. eg: /testem/phys/setCuts 100 microm /run/initialize The shower profiles are histogramed, if histograming is activated. They can be also printed with the command /testem/run/verbose 1 6- HOW TO START ? - compile and link to generate an executable % cd TestEm2 % gmake - execute TestEm2 in 'batch' mode from macro files % TestEm2 run01.mac - execute TestEm2 in 'interactive mode' with visualization % TestEm2 .... Idle> type your commands .... Idle> exit 7- HISTOGRAMS TestEm2 produces several histograms: Content of these histo: 1 : energy deposit per event 2 : charged track length per event 3 : neutral track length per event 4 : longitudinal energy profile 5 : rms of longitudinal energy profile 6 : cumulated longitudinal energy profile 7 : rms of cumulated longitudinal energy profile 8 : radial energy profile 9 : rms of radial energy profile 10 : cumulated radial energy profile 11 : rms of cumulated radial energy profile Note that, by default, histograms are disabled. To activate them, uncomment the flag G4ANALYSIS_USE in GNUmakefile. To define the output file name with histograms and the type of these file the following UI commands can be used: "/testem/histo/setFileName name" "/testem/histo/setFileType type" The following types are available: "hbook", "root", "XML" By default the name is "testem2" and the type "root". Before compilation of the example it is optimal to clean up old files: gmake histclean gmake 8- USING HISTOGRAMS To use histograms, at least one of the AIDA implementations should be available. See InstallAida.txt