Gabriele Cosmo
113 lines
4.1 KiB
Plaintext
113 lines
4.1 KiB
Plaintext
-------------------------------------------------------------------
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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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TestEm17
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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 transfered 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 of the example uses the main physics constructor
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(builder) called "emstandard_opt0". As an alternative "local"
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constructor is provided in which only a limited set
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of physics processes are defined for muons, pions and proton:
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ionisation, bremsstrahlung and e+e- pair production.
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Default energy range for EM processes in this example
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is from 100*eV to 1000*PeV.
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Optionally "muNucl" builder may be added activating muon-nuclear
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inelastic interaction.
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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
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particles 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 cross
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section 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 theoretical cross sections have been
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provided by the G4 MEPhI group, and grouped in MuCrossSections class.
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5- HISTOGRAMS
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The test contains built-in 1D histograms for muons filled during
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Monte Carlo simulation, which are managed by the HistoManager class
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and its Messenger:
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1 Relative muon transferred energy distribution
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(log10(eps/Emu kin) for knock-on electrons (ionization)
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2 -"- direct (e+,e-) pair production by muons
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3 -"- bremsstrahlung by muons
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4 -"- nuclear interaction by muons
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5 ionistion for hadrons
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6 (e+,e-) pair production by hadrons
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7 bremsstrahlung by hadrons
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The histos can be activated individually with the command :
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/testem/histo/setHisto id nbBins valMin valMax :
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min and max values of log10(eps/Emu kin).
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At EndOfRun the corresponding histos for analytic calculations are
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automatically created and filled (histo 11 to 14).
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One can control the name and the type of the histograms file with
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the command:
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/testem/histo/setFileName name (default testem17)
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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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execute TestEm17 in 'batch' mode from macro files :
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% TestEm17 allproc.mac
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execute TestEm17 in 'interactive mode' with visualization :
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% TestEm17
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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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