Gabriele Cosmo
84 lines
3.2 KiB
Plaintext
84 lines
3.2 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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Extended Example for G4GeneralParticleSource (GPS)
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exgps is created to demonstrate the usage of G4GeneralParticleSource for generating
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primary incident particle according to user defined distributions. These range from simple
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monocromatic point source to complicated mutiple sources with various biasing schemes.
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More detailed information on the usage of GPS are available on its home site:
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http://reat.space.qinetiq.com/gps
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1. GEOMETRY
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Simple geometry consists of a "Vacuum" world and, in it with two other components:
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- An alunimium box : 20 x 20 x 20 cm in size, cerntered at the origin.
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- A SiO2 sphere: 5 cm in radius and is placed in the centre of the aluminium box.
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2. PHYSICS
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Tranportation process only for all particles.
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3. EVENT:
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The event generator is the G4GeneralParticleSource (GPS). The instantiation of G4GeneralParticleSource
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is same as that for G4ParticleGun. See the exGPSPrimaryGeneratorAction.cc file for details .
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5. VISUALIZATION:
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Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An
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example of displaying the geometry and tracks using VRML is given in the macro file vis.mac.
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6. ANALYSIS:
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This example implements an analysis manager which creates histograms and ntuples
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using Geant4 analysis tools.
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At the end of an excution, an xml file "exGPS.root" is created by default which contains
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histograms and ntuples.
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The output file contains 6 histograms and one ntuple:
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histogram 1: The energy spectrum of the primary particles.
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histogram 2: 2d histogram of primary particle incident position distribution in the X-Y plane.
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histogram 3: 2d histogram of primary particle incident position distribution in the X-Z plane.
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histogram 4: 2d histogram of primary particle incident position distribution in the Y-Z plane.
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histogram 5: 2d histogram of primary particle incident angle distribution in terms of Phi/Cos(Theta).
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histogram 6: 2d histogram of primary particle incident angle distribution in terms of Phi/Theta.
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The binnings of the histograms can be changed with the UI commands avialable under the
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/analysis directory.
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In the ntuple the following data are recorded for each incident particle:
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Particle ID
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Incident Position (x,y,z);
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Incident Angle (theta,phi);
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Particle weight;
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7. GETTING STARTED:
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Run the executable:
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while in the exgps build directory do
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exgps exrgps.in
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8. FURTHER EXAMPLES of MACRO FILES:
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There are a number of g4mac files in the ./macros subdirectory, to show the various features of GPS.
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Most of them will lead to the creation of a Root file in the same name as the macro file.
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These files can be then examined and analysed with ROOT.
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Please see the README file there for further information.
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