Gabriele Cosmo
150 lines
5.0 KiB
Plaintext
150 lines
5.0 KiB
Plaintext
$Id: README,v 1.2 2004/06/23 11:28:04 maire Exp $
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-------------------------------------------------------------------
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=========================================================
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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=========================================================
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MuonProcesses
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-------------
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This example is intended to check implementation of the processes
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of muon interactions: ionization, direct (e+,e-) production,
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bremsstrahlung, mu-nuclear interaction.
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It allows to compute differential cross sections (as function of the
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energy tranfered to secondaries), total cross sections and to compare
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with analytic calculations.
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1- GEOMETRY DEFINITION
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It is a single box of homogeneous medium.
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Two parameters define the geometry :
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- the material of the box,
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- the (full) size of the box.
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The default geometry (1 m of Iron) is constructed in
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DetectorConstruction, but the above parameters can be changed
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interactively via the commands defined in DetectorMessenger.
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2- PHYSICS LIST
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The physics list contains only electromagnetic processes for muon,
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adding G4MuNuclearInteraction and seting of upper energy range limit
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to 1000 PeV).
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Standard (default) and g4v52 (frozen at the release Genat4 v.5.2)
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physics can be choosen.
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3- AN EVENT : THE PRIMARY GENERATOR
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The primary kinematic consists of a single particle starting at the edge
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of the box. The type of the particle and its energy are set in
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PrimaryGeneratorAction (mu+ 10 TeV), and can be changed via the G4
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build-in commands of ParticleGun class (see the macros provided with
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this example).
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4- PHYSICS
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The incident particle is a muon. During the tracking, secondary particles
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are killed.
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The number of interactions are plotted as a function of the energy
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transfered to the secondaries.
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The total number of interactions is recorded, and the total crossSection
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computed from this.
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At EndOfRun, the above results are compared with analytic calculations.
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The functions which compute the theoritical crossSections have been
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provided by the G4 MEPhI group, and grouped in MuCrossSection class.
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5- HISTOGRAMS
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The test contains 4 built-in 1D histograms, which are managed by the
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HistoManager class and its Messenger.
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1 Monte-Carlo relative transferred energy distribution histo
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(log10(eps/Emu kin) for knock-on electrons (ionization)
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2 -"- direct (e+,e-) pair production
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3 -"- bremsstrahlung
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4 -"- nuclear interaction
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The histos can be activated individually with the command :
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/testem/histo/setHisto id nbBins valMin valMax : min and max values of
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log10(eps/Emu kin).
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At EndOfRun the corresponding histos for analytic calculations are
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automatically created anf filled (histo 6 to 9), and the comparison
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(G4 divided by theory) is done in histos 11 to 14.
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The histograms can be viewed using PAW. See below the note on
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ANAPHE+AIDA.
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Note that, by default, histograms are disabled. To activate them,
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uncomment the flag G4ANALYSIS_USE in GNUmakefile.
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6- VISUALIZATION
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The Visualization Manager is set in the main().
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The initialisation of the drawing is done via the commands
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/vis/... in the macro vis.mac. To get visualisation:
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> /control/execute vis.mac
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The detector has a default view which is a longitudinal view of the
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box.
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The tracks are drawn at the end of event, and erased at the end of run.
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7- HOW TO START ?
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compile and link to generate an executable
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% cd geant4/examples/extended/electromagnetic/MuonProcesses
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% gmake
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execute MuonProcesses in 'batch' mode from macro files :
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% MuonProcesses allproc.mac
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execute MuonProcesses in 'interactive mode' with visualization :
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% MuonProcesses
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Idle> control/execute vis.mac
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....
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Idle> type your commands
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....
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Idle> exit
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8- Using histograms
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-------------------
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By default the histograms are not activated. To activate histograms
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the environment variable G4ANALYSIS_USE should be defined. For instance
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uncomment the flag G4ANALYSIS_USE in GNUmakefile.
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To use histograms any of implementations of AIDA interfaces should
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be available (see http://aida.freehep.org).
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A package including AIDA and extended interfaces also using Python
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is PI, available from: http://cern.ch/pi .
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Once installed PI or PI-Lite in a specified local area $MYPY, it is
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required to add the installation path to $PATH, i.e. for example,
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for release 1.2.1 of PI:
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setenv PATH ${PATH}:$MYPI/1.2.1/app/releases/PI/PI_1_2_1/rh73_gcc32/bin
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CERN users can use the PATH to the LCG area on AFS.
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Before compilation of the example it is optimal to clean up old
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files:
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gmake histclean
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gmake
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Before running the example the command should be issued:
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eval `aida-config --runtime csh`
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It is possible to choose the format of the output file with
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histograms using UI command:
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/testem/histo/setFileType type
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The following types are available: hbook, root, xml.
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