| Geant4 Cross Reference |
1 ------------------------------------------------------------------- 2 3 ========================================================= 4 Geant4 - an Object-Oriented Toolkit for Simulation in HEP 5 ========================================================= 6 7 Example Par03 8 ------------- 9 10 This example demonstrates how to use G4FastSimHitMaker helper class 11 to create multiple energy deposits from the fast simulation model. 12 13 It requires sensitive detector class to inherit from both base classes: 14 - G4VSensitiveDetector: for processing of detailed/non-fast simulation hits 15 - G4VFastSimSensitiveDetector: for processing of fast sim (G4FastSim) hits 16 Hits are placed in the same hit collection, so they can be used to 17 compare between the full and the fast simulation. 18 19 The geometry used in the example is a homogeneous cylinder of lead, with 20 3D readout geometry (cylindrical). Analysis of energy deposits is done 21 in the event action. 22 23 1. Detector description 24 ----------------------- 25 26 The detector is a homogeneous cylinder of lead. It is segmented along 27 z, R and phi to create a readout geometry in the cylindrical coordinates. 28 29 Fast simulation is attached to the region of the detector. 30 31 32 2. Sensitive detector 33 ----------------------- 34 35 Sensitive detector inherits from both base classes: 36 - G4VSensitiveDetector: for processing of detailed/non-fast simulation hits 37 - G4VFastSimSensitiveDetector: for processing of fast sim (G4FastSim) hits. 38 Hits are placed in the same hit collection, with a different flag to distinguish 39 between those originated in the full simulation, and those from the fast 40 simulation. 41 During visualisation, hits are represented as volumes of different colour: 42 green for full simulation and red for fast simulation. 43 44 3. Primary generation 45 --------------------- 46 47 Particle gun is used as a primary generator. The direction of particles is along 48 the axis of symmetry of the detector (cylinder). It is positioned 10 cm in front 49 of the entrance to the detector. 10 GeV electron is used by default. Those values 50 can be changed using /gun/ UI commands. 51 52 4. Physics List 53 --------------- 54 55 FTFP_BERT modular physics list is used. On top of it, fast simulation physics 56 is registered for selected particles (electrons, positrons, and photons). 57 58 59 5. User actions 60 ---------------------------------------------------------- 61 62 - Par03RunAction : run action used for initialization and termination 63 of the run. Histograms for analysis of shower development 64 in the detector are created. 65 66 - Par03EventAction : event action used for initialization and termination 67 of the event. Analysis of shower development is performed 68 on event-by-event basis. 69 70 6. Output 71 --------- 72 73 The execution of the program (examplePar03) produces an output with histograms. 74 75 The macro file examplePar03.in specifies three runs. Each run is made of 100 76 events, for single 10 GeV electron beams. The first run is executed with fast 77 simulation model activated with defualt parameters. The second run executes fast 78 simulation with modified parameters. For the third run the fast simulation model 79 is disactivated. 80 Three output files are produced: two with shower development from the fast 81 simulation (with different parameters), and from the full simulation. 82 83 7. How to build and run the example 84 ----------------------------------- 85 86 - Compile and link to generate the executable (in your CMAKE build directory): 87 % cmake <PAR03_SOURCE> 88 % make 89 90 - Execute the application (in batch mode): 91 % ./examplePar03 -m examplePar03.in 92 which produces three root files: Par03_fastsim_100events.root, 93 Par03_fastsimModified_100events.root, and Par03_fullsim_100events.root. 94 95 - Execute the application (in interactive mode): 96 % ./examplePar03 97 which allows to visualize hits. 98 99 8. UI commands 100 -------------- 101 102 UI commands useful in this example: 103 104 - activation/disactivation of the fast simulation model: 105 /param/ActivateModel model 106 /param/InActivateModel model 107 108 - particle gun commands 109 /gun/particle e+ 110 /gun/energy 50 GeV 111 /gun/direction 0 0.2 1 112 /gun/position 0 0 0 113 114 UI commands defined in this example: 115 - detector settings 116 /Par03/detector/print 117 /Par03/detector/setDetectorRadius 10 cm 118 /Par03/detector/setDetectorLength 30 cm 119 /Par03/detector/setDetectorMaterial G4_Pb 120 /Par03/detector/setNbOfLayers 100 121 /Par03/detector/setNbOfPhiCells 20 122 /Par03/detector/setNbOfRhoCells 100 123 124 - fast simulation settings 125 /Par03/fastSim/print 126 /Par03/fastSim/transverseProfile/sigma 20 mm 127 /Par03/fastSim/longitudinalProfile/beta 0.6 128 /Par03/fastSim/longitudinalProfile/alpha 2. 129 /Par03/fastSim/longitudinalProfile/maxDepth 20 130 /Par03/fastSim/numberOfHits 500