Gabriele Cosmo
263 lines
9.5 KiB
Plaintext
263 lines
9.5 KiB
Plaintext
$Id: README,v 1.2 2000/12/06 16:53:12 flongo Exp $
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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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gammaray_telescope
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------------------
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F.Longo, R.Giannitrapani & G.Santin
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December 2000
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--------------------------------------------------------------
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Acknowledgments to GEANT4 people, in particular to R.Nartallo,
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A.Pfeiffer, M.G.Pia and G.Cosmo
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--------------------------------------------------------------
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GammaRayTel is an example of application of Geant4 in a space
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envinronment. It simulates a typical telescope for gamma ray analysis;
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the detector setup is composed by a tracker made with silicon planes,
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subdivided in ladders and strips, a CsI calorimeter and an
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anticoincidence system. In this version, only the tracker is made
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sensitive; the hits on the tracker strips are registered and relevant
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information (energy deposition, position etc) are dumped to an external
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ASCII file for subsequent analysis. If Lizard is available on the user
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platform, than some histograms with relevant hits information are
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displayed and saved as PostScript files.
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The main features of this example are
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a) Macros for the visualization of geometry and tracks with
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OpenGL, VRML and DAWN drivers
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b) Implementation of messengers to change some parameters of
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the detector geometry, the particle generator and the analysis
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manager (if present) runtime
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c) Readout geometry mechanism to describe an high number of
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subdivisions of the planes of the tracker (strips) without
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affecting in a relevant way the simulation performances
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d) Histogramming for Linux and Solaris platform via the
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Lizard system (tested on Linux platform); this is a preliminary
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feature of GEANT4, so expect some changes and/or improvements in
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future releases
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e) User interfaces via Xmotif or normal terminal provided
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1. Setting up the environment variables
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---------------------------------------
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- Setup for Visualization
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IMPORTANT: be sure that your Geant4 installation has been done
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with the proper visualization drivers; for details please see the
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file geant4/source/visualization/README.
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To use the visualization drivers set the following variables in
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your local environment:
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setenv G4VIS_USE_OPENGLX 1 # OpenGL visualization
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setenv G4VIS_USE_DAWNFILE 1 # DAWN file
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setenv G4VIS_USE_VRMLFILE 1 # VRML file
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setenv G4VRMLFILE_VIEWER vrmlview # If installed
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- Setup for Xmotif user interface
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setenv G4UI_USE_XM 1
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- Set up for analysis using Lizard
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IMPORTANT: be sure that your G4 installation has been done properly;
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in particular be sure that the following environment variables are
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set prior to build the library (this is working only on Linux and
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Solaris platform)
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setenv G4ANALYSIS_BUILD 1 # Build the analysis tools
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setenv G4ANALYSIS_BUILD_LIZARD 1 # Build the Lizard interface
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setenv LIZARDROOT /usr/local/freeLizard/3.2.0 #get correct path
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For example at CERN the path is
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setenv LIZARDROOT /afs/cern.ch/project/asddat/lhcxx/3.2.0/freeLizard/3.2.0
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To compile the GammaRayTel example with the analysis tools activated,
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set the following variables
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setenv G4ANALYSIS_USE 1 # Use the analysis tools
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setenv G4ANALYSIS_USE_LIZARD 1 # Use the Lizard one
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and be sure to have the right path to the Lizard library
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#add to the LD_LIBRARY_PATH (get correct path)
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setenv LD_LIBRARY_PATH /usr/local/freeLizard/3.2.0/Linux/lib
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For example at CERN the path is
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setenv LD_LIBRARY_PATH /afs/cern.ch/project/asddat/lhcxx/3.2.0/freeLizard/3.2.0/Linux/lib
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2. Sample run
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-------------
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To run a sample simulation with gamma tracks interacting with
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the detector in its standard configuration and without any
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visualization, execute the following command in the example main
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directory:
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$G4WORKDIR/bin/$G4SYSTEM/GammaRayTel
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It is possible also to run three different configuration defined in
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macro1.mac, macro2.mac and macro3.mac for visualization (OpenGL, VRML
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and DAWN respectively) with the following command
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$G4WORKDIR/bin/$G4SYSTEM/GammaRayTel macroX.mac
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where X can be 1, 2 or 3. Be sure to have the right environment (see
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the preceding section) and the proper visualization driver enabled in
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your local G4 installation (see geant4/source/visualization/README for
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more information).
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3. Detector description
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-----------------------
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The detector is defined in GammaRayTelDetectorConstruction.cc
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It is composed of a Payload with three main detectors, a Tracker (TKR), a
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Calorimeter (CAL) and an Anticoincidence system (ACD).
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The standard configuration is made of a TKR of 15 Layers of Si detectors,
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with Lead converter, and a CAL of 8 layers of CsI. 4 lateral panels and a
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top layer of plastic scintillator (ACT and ACL) complete the configuration.
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The Si detectors are composed of two silicon planes subdivided in strips
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aligned along the X axis in one plane and along the Y axis for the other.
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It is possible to modify in some way this configuration using the
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commands defined in GammaRayTelDetectorMessenger.
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This feature is available in the UI throught the commands subtree
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"/payload/" (see the help command in the UI for more information).
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4. Physics processes
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--------------------
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This example uses the standard Electromagnetic processes.
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5. Particle Generator
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---------------------
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The GammaRayTelParticleGenerationAction and its Messenger let the user define
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the incident flux of particles, from a specific direction or from an
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isotropic background. The user can define also between two spectral options:
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monochromatic or with a power-law dependence. The particle
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generator parameters are accessible throught the UI tree "/gun/" (use the
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UI help for more information). We are planning to include, in the next
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release of this example, the new General Particle Source module of G4.
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6. ReadOutGeometry
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------------------
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The tracker is made of Silicon Microstrips detectors. The ReadOut geometry
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provides the description of the strips.
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7. Hit
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------
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In this version only the hits from the TKR are recorded. Each hit
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contains the following information
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a) ID of the event (this is important for multiple events run)
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b) Energy deposition of the particle in the strip (keV)
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c) Number of the strip
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d) Number of the plane
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e) Type of the plane (1=X 0=Y)
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f) Position of the hit (x,y,z) in the reference frame of the payload
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The hit information are saved on an ASCII file named Tracks_N.dat, where
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N is the progressive ID number associated to the run.
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8. Histogramming
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----------------
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Some hits information can be visualized runtime using Lizard (if it is
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available on the user platform); two 2D histograms and two 1D histograms
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can be visualized and saved (as PostScript files) during the simulation
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run. The 2D histograms contain the hits positions on the TKR projected on
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the XZ plane and the YZ plane; the 1D histograms contain the energy
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deposition in the last X plane of the TKR and the hits distribution along
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the X planes of the TKR (note that this histograms have been chosen more
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for pedagogical motivation than for physical one).
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These histograms are filled and updated at every event and are initialized
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with each new run; the scale of the histograms is automatically derived from
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the detector geometry.
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Throught a messenger it is possible to set some options with
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the UI subtree "/analysis/" (use the UI help for more info); in particular
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it is possible to enable or disable the drawing of the 1D and 2D histograms
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at every event and to enable or disable the saving of PostScript files at the
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end of each run. If you feel that the simulation is too slow with the
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histograms updated every event, you can disable the drawing and retain
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the saving. Please note that the updating of the histograms is triggered
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only when there is some hit in an event.
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In this example we only show the use of very basic feature of this new
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simulation/analysis framework; histogramming and analysis in Geant4
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are in an evolving phase, so expect some changes and/or improvements
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for next releases.
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9. Classes Overview
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-------------------
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This is the overview of the classes defined in this example
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GammaRayTelPrimaryGeneratorAction
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User action for primaries generator
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GammaRayTelPrimaryGeneratorMessenger
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Messenger for interactive particle generator
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parameters modification via the User Interface
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GammaRayTelPhysicsList
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Determination of particles and processes active in this
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example
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GammaRayTelTelVisManager
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Visualization manager class
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GammaRayTelDetectorConstruction
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Geometry and material definitions for the detector
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GammaRayTelDetectorMessenger
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Messenger for interactive geometry parameters
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modification via the User Interface
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GammaRayTelAnalysisManager
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Analysis manager class with Lizard tool (experimental)
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GammaRayTelAnalysisMessenger
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Messenger for interactive analysis options modification
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via the User Interface
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GammaRayTelRunAction
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User run action class
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GammaRayTelEventAction
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User event action class
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GammaRayTelPayloadHit
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Description of the hits on the tracker
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GammaRayTelPayloadROGeometry
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Description of the readout geometry for strips subdivision
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GammaRayTelPayloadSD
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Description of the sensitive detector
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