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0001 -------------------------------------------------------------------
0002
0003 =========================================================
0004 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0005 =========================================================
0006
0007 Example Par03
0008 -------------
0009
0010 This example demonstrates how to use G4FastSimHitMaker helper class
0011 to create multiple energy deposits from the fast simulation model.
0012
0013 It requires sensitive detector class to inherit from both base classes:
0014 - G4VSensitiveDetector: for processing of detailed/non-fast simulation hits
0015 - G4VFastSimSensitiveDetector: for processing of fast sim (G4FastSim) hits
0016 Hits are placed in the same hit collection, so they can be used to
0017 compare between the full and the fast simulation.
0018
0019 The geometry used in the example is a homogeneous cylinder of lead, with
0020 3D readout geometry (cylindrical). Analysis of energy deposits is done
0021 in the event action.
0022
0023 1. Detector description
0024 -----------------------
0025
0026 The detector is a homogeneous cylinder of lead. It is segmented along
0027 z, R and phi to create a readout geometry in the cylindrical coordinates.
0028
0029 Fast simulation is attached to the region of the detector.
0030
0031
0032 2. Sensitive detector
0033 -----------------------
0034
0035 Sensitive detector inherits from both base classes:
0036 - G4VSensitiveDetector: for processing of detailed/non-fast simulation hits
0037 - G4VFastSimSensitiveDetector: for processing of fast sim (G4FastSim) hits.
0038 Hits are placed in the same hit collection, with a different flag to distinguish
0039 between those originated in the full simulation, and those from the fast
0040 simulation.
0041 During visualisation, hits are represented as volumes of different colour:
0042 green for full simulation and red for fast simulation.
0043
0044 3. Primary generation
0045 ---------------------
0046
0047 Particle gun is used as a primary generator. The direction of particles is along
0048 the axis of symmetry of the detector (cylinder). It is positioned 10 cm in front
0049 of the entrance to the detector. 10 GeV electron is used by default. Those values
0050 can be changed using /gun/ UI commands.
0051
0052 4. Physics List
0053 ---------------
0054
0055 FTFP_BERT modular physics list is used. On top of it, fast simulation physics
0056 is registered for selected particles (electrons, positrons, and photons).
0057
0058
0059 5. User actions
0060 ----------------------------------------------------------
0061
0062 - Par03RunAction : run action used for initialization and termination
0063 of the run. Histograms for analysis of shower development
0064 in the detector are created.
0065
0066 - Par03EventAction : event action used for initialization and termination
0067 of the event. Analysis of shower development is performed
0068 on event-by-event basis.
0069
0070 6. Output
0071 ---------
0072
0073 The execution of the program (examplePar03) produces an output with histograms.
0074
0075 The macro file examplePar03.in specifies three runs. Each run is made of 100
0076 events, for single 10 GeV electron beams. The first run is executed with fast
0077 simulation model activated with defualt parameters. The second run executes fast
0078 simulation with modified parameters. For the third run the fast simulation model
0079 is disactivated.
0080 Three output files are produced: two with shower development from the fast
0081 simulation (with different parameters), and from the full simulation.
0082
0083 7. How to build and run the example
0084 -----------------------------------
0085
0086 - Compile and link to generate the executable (in your CMAKE build directory):
0087 % cmake <PAR03_SOURCE>
0088 % make
0089
0090 - Execute the application (in batch mode):
0091 % ./examplePar03 -m examplePar03.in
0092 which produces three root files: Par03_fastsim_100events.root,
0093 Par03_fastsimModified_100events.root, and Par03_fullsim_100events.root.
0094
0095 - Execute the application (in interactive mode):
0096 % ./examplePar03
0097 which allows to visualize hits.
0098
0099 8. UI commands
0100 --------------
0101
0102 UI commands useful in this example:
0103
0104 - activation/disactivation of the fast simulation model:
0105 /param/ActivateModel model
0106 /param/InActivateModel model
0107
0108 - particle gun commands
0109 /gun/particle e+
0110 /gun/energy 50 GeV
0111 /gun/direction 0 0.2 1
0112 /gun/position 0 0 0
0113
0114 UI commands defined in this example:
0115 - detector settings
0116 /Par03/detector/print
0117 /Par03/detector/setDetectorRadius 10 cm
0118 /Par03/detector/setDetectorLength 30 cm
0119 /Par03/detector/setDetectorMaterial G4_Pb
0120 /Par03/detector/setNbOfLayers 100
0121 /Par03/detector/setNbOfPhiCells 20
0122 /Par03/detector/setNbOfRhoCells 100
0123
0124 - fast simulation settings
0125 /Par03/fastSim/print
0126 /Par03/fastSim/transverseProfile/sigma 20 mm
0127 /Par03/fastSim/longitudinalProfile/beta 0.6
0128 /Par03/fastSim/longitudinalProfile/alpha 2.
0129 /Par03/fastSim/longitudinalProfile/maxDepth 20
0130 /Par03/fastSim/numberOfHits 500
