Gabriele Cosmo
128 lines
5.0 KiB
Plaintext
128 lines
5.0 KiB
Plaintext
$Id: README 86064 2014-11-07 08:49:32Z gcosmo $
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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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electronScattering
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------------------
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Electron scattering benchmark (T. O'Shea and B. Faddegon)
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1- GEOMETRY DEFINITION
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The geometry is described in the enclosed documument : NRCC_electron_scat.pdf
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A "World" volume contains a "Frame" made of Air.
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The Frame contains : ExitWindow, ScatterFoil, MonitorChbr, Bag.
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The Bag contains a Gas volume, which contains 2 aluminium Rings
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The Scoring plane is the end-plane of the Frame
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The default geometry is constructed in DetectorConstruction class.
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The parameters of the ScatterFoil (material and thickness) must be defined
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via 2 UI commands : see the macro scatter.mac
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2- PHYSICS LIST
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Physics lists can be local (eg. in this example) or from G4 kernel
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physics_lists subdirectory.
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Local physics lists:
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- "local" standard EM physics with current 'best' options setting.
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these options are explicited in PhysListEmStandard
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- "standardSS" standard EM physics with single Coulomb scattering
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instead of multiple scattering
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From geant4/source/physics_lists/builders:
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- "emstandard_opt0" recommended standard EM physics for LHC
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- "emstandard_opt1" best CPU performance standard physics for LHC
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- "emstandard_opt2" alternative models
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- "emstandard_opt3" current state of art for EM physics
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analog to "local"above
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Physics lists and options can be (re)set with UI commands
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Please, notice that options set through G4EmProcessOPtions are global, eg
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for all particle types. In G4 builders, it is shown how to set options per
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particle type.
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3- PRIMARY GENERATOR : mono-enegetic pencil beam
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The primary kinematic consists of a single particle which hits the detector
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perpendicular to the input face (ExitWindow). The type of the particle and its
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energy are set in the PrimaryGeneratorAction class, and can be changed via
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the G4 build-in commands of ParticleGun class.
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(see the macros provided with this example)
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The incident beam has a Gaussian-shaped spatial distribution. The rms of the
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Gaussian can be define with an UI command built in PrimaryGeneratorMessenger.
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4- 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 in vis.mac
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In interactive session:
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PreInit or Idle > /control/execute vis.mac
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The example has a default view which is a longitudinal view of the detector.
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The tracks are drawn at the end of event, and erased at the end of run.
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Optionaly one can choose to draw all particles, only the charged, or none.
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This command is defined in EventActionMessenger class.
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5- TRACKING
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One can limit 'by hand' the step lenght of the particle. As an example,
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this limitation is implemented as a 'full' process : see StepMax class and its
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Messenger. The 'StepMax process' is registered in the Physics List.
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6- DETECTOR RESPONSE
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At the end of a run, from the histogram(s), one can study different
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physics quantities, via the histograms defined below.
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An ascii file corresponding to histo 4 (see below) is automatically written.
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7- List of the built-in histograms
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----------------------------------
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The test contains 4 built-in 1D histograms, which are managed by
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G4AnalysisManager class and its Messenger. The histos can be individually activated
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with the command :
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/analysis/h1/set id nbBins valMin valMax unit
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where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
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(see the macros xxxx.mac).
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1 "(charged particles): projected angle at Scoring plane"
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2 "(charged particles): dN/dS at Scoring plane"
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3 "(charged particles): d(N/cost)/dS at Scoring plane"
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4 "(charged particles): normalized d(N/cost)/dS at Scoring plane"
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5 "(charged particles); scattering angle theta"
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6 "(charged particles); measured scattering angle theta"
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The histograms can be viewed using ROOT or PAW.
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One can control the name and format of the histograms file with the command:
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/analysis/setFileName name (default nrccBenchmark)
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It is possible to choose the format of the histogram file : root (default),
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xml, csv, by using namespace in HistoManager.hh
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It is also possible to print selected histograms on an ascii file:
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/analysis/h1/setAscii id
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All selected histos will be written on a file name.ascii (default nrccBenchmark)
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8- HOW TO START ?
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- execute electronScattering in 'batch' mode from macro files e.g.
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% electronScattering myMacro.mac
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- execute electronScattering in 'interactive' mode with visualization e.g.
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% electronScattering
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Then type your commands, for instance :
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Idle> control/execute vis.mac
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Idle> run/beamOn 5
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....
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