Gabriele Cosmo
130 lines
4.7 KiB
Plaintext
130 lines
4.7 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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Example Par03
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-------------
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This example demonstrates how to use G4FastSimHitMaker helper class
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to create multiple energy deposits from the fast simulation model.
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It requires sensitive detector class to inherit from both base classes:
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- G4VSensitiveDetector: for processing of detailed/non-fast simulation hits
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- G4VFastSimSensitiveDetector: for processing of fast sim (G4FastSim) hits
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Hits are placed in the same hit collection, so they can be used to
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compare between the full and the fast simulation.
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The geometry used in the example is a homogeneous cylinder of lead, with
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3D readout geometry (cylindrical). Analysis of energy deposits is done
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in the event action.
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1. Detector description
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-----------------------
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The detector is a homogeneous cylinder of lead. It is segmented along
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z, R and phi to create a readout geometry in the cylindrical coordinates.
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Fast simulation is attached to the region of the detector.
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2. Sensitive detector
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-----------------------
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Sensitive detector inherits from both base classes:
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- G4VSensitiveDetector: for processing of detailed/non-fast simulation hits
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- G4VFastSimSensitiveDetector: for processing of fast sim (G4FastSim) hits.
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Hits are placed in the same hit collection, with a different flag to distinguish
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between those originated in the full simulation, and those from the fast
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simulation.
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During visualisation, hits are represented as volumes of different colour:
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green for full simulation and red for fast simulation.
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3. Primary generation
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---------------------
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Particle gun is used as a primary generator. The direction of particles is along
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the axis of symmetry of the detector (cylinder). It is positioned 10 cm in front
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of the entrance to the detector. 10 GeV electron is used by default. Those values
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can be changed using /gun/ UI commands.
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4. Physics List
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---------------
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FTFP_BERT modular physics list is used. On top of it, fast simulation physics
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is registered for selected particles (electrons, positrons, and photons).
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5. User actions
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----------------------------------------------------------
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- Par03RunAction : run action used for initialization and termination
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of the run. Histograms for analysis of shower development
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in the detector are created.
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- Par03EventAction : event action used for initialization and termination
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of the event. Analysis of shower development is performed
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on event-by-event basis.
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6. Output
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---------
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The execution of the program (examplePar03) produces an output with histograms.
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The macro file examplePar03.in specifies three runs. Each run is made of 100
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events, for single 10 GeV electron beams. The first run is executed with fast
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simulation model activated with defualt parameters. The second run executes fast
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simulation with modified parameters. For the third run the fast simulation model
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is disactivated.
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Three output files are produced: two with shower development from the fast
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simulation (with different parameters), and from the full simulation.
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7. How to build and run the example
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-----------------------------------
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- Compile and link to generate the executable (in your CMAKE build directory):
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% cmake <PAR03_SOURCE>
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% make
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- Execute the application (in batch mode):
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% ./examplePar03 -m examplePar03.in
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which produces three root files: Par03_fastsim_100events.root,
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Par03_fastsimModified_100events.root, and Par03_fullsim_100events.root.
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- Execute the application (in interactive mode):
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% ./examplePar03
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which allows to visualize hits.
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8. UI commands
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--------------
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UI commands useful in this example:
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- activation/disactivation of the fast simulation model:
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/param/ActivateModel model
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/param/InActivateModel model
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- particle gun commands
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/gun/particle e+
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/gun/energy 50 GeV
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/gun/direction 0 0.2 1
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/gun/position 0 0 0
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UI commands defined in this example:
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- detector settings
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/Par03/detector/print
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/Par03/detector/setDetectorRadius 10 cm
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/Par03/detector/setDetectorLength 30 cm
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/Par03/detector/setDetectorMaterial G4_Pb
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/Par03/detector/setNbOfLayers 100
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/Par03/detector/setNbOfPhiCells 20
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/Par03/detector/setNbOfRhoCells 100
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- fast simulation settings
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/Par03/fastSim/print
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/Par03/fastSim/transverseProfile/sigma 20 mm
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/Par03/fastSim/longitudinalProfile/beta 0.6
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/Par03/fastSim/longitudinalProfile/alpha 2.
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/Par03/fastSim/longitudinalProfile/maxDepth 20
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/Par03/fastSim/numberOfHits 500 |