Gabriele Cosmo
172 lines
5.6 KiB
Plaintext
172 lines
5.6 KiB
Plaintext
$Id: README,v 1.5 2000/12/06 18:34:42 nartallo 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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xray_telescope
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--------------
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XrayTel is an advanced Geant4 example based on a realistic simulation of
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an X-ray Telescope. It is based on work carried out by a team of Geant4
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experts to simulate the interaction between X-ray Telescopes XMM-Newton
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and Chandra with low energy protons present in the orbital radiation
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background. The X-ray mirrors are designed to collect x-ray photons at
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grazing-incidence angles and focus them onto detectors at the focal plane.
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However, this mechanism also seems to work for low energy protons which,
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if they reach the detectors in sufficient numbers, can cause damage.
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In this example, the geometry has been simplified by using a single mirror
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shell and no baffles, but all the dimensions and materials are realistic.
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The aim of this advanced example is to illustrate the use advanced
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GUI, visualisation, particle generation and analysis schemes available
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in Geant4:
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- the simulation can be run from GAG or the command prompt
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- macros are provided to display the geometry and particle tracks with
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OpenGL, DAWN Postscript or VRML visualisation
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- the generation of particles is done via the new General Particle Source
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- histograming facilities are provided for the Linux environment only
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with the Lizard system at present, other analysis systems such as
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OpenScientist and JAS will be implemented at a later stage
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In order to be able to use any of these packages, prior installation is
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necessary and a number of environment variables will have to be set.
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1. Setting up the environment variables for GAG, Visualisation and
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Analysis options (example based on Linux at CERN)
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#set up GAG
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setenv G4UI_BUILD_GAG_SESSION 1
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setenv G4UI_USE_GAG 1
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#set up VRMLview
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setenv G4VIS_BUILD_VRMLFILE_DRIVER 1
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setenv G4VIS_USE_VRML 1
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setenv G4VIS_USE_VRMLFILE 1
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setenv G4VRMLFILE_MAX_FILE_NUM 100
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setenv G4VRMLFILE_VIEWER vrmlview #if installed
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setenv G4VIS_USE_VRML 1
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setenv G4VIS_USE_VRMLFILE 1
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setenv PATH ${PATH}:"/afs/cern.ch/sw/contrib/VRML/bin/Linux"
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#set up OpenGL or Mesa
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setenv G4VIS_BUILD_OPENGLX_DRIVER 1
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setenv G4VIS_USE_OPENGLX 1
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setenv OGLHOME /afs/cern.ch/sw/geant4/dev/Mesa/Linux-g++
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#set up DAWN
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setenv G4VIS_BUILD_DAWN_DRIVER 1
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setenv G4VIS_BUILD_DAWNFILE_DRIVER 1
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setenv G4VIS_USE_DAWN 1
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setenv G4VIS_USE_DAWNFILE 1
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setenv PATH ${PATH}:"/afs/cern.ch/sw/geant4/dev/DAWN/Linux-g++"
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#set up Lizard
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setenv LIZARDROOT /usr/local/freeLizard/3.2.0 #get correct path
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setenv G4ANALYSIS_SYSTEM Lizard
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setenv G4ANALYSIS_USE 1
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setenv G4ANALYSIS_USE_LIZARD 1
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setenv G4ANALYSIS_BUILD 1
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setenv G4ANALYSIS_BUILD_LIZARD 1
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#add to the LD_LIBRARY_PATH
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setenv LD_LIBRARY_PATH /usr/local/freeLizard/3.2.0/Linux/lib:$OGLHOME/lib
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IMPORTANT WARNING!
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setenv G4ANALYSIS_BUILD 1
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must always be set to build the example even if the analysis option
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is not required
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Sources
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-------
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GAG can be obtained from
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http://erpc1.naruto-u.ac.jp/~geant4/
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OpenGL Mesa needs to be installed prior to building Geant4 and can be
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downloaded from
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http://www.mesa3d.org/download.html
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DAWN can be obtained from
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http://133.7.51.8/dawn/
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VRMLview for Linux can be obtained from
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2. Run
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To execute a sample simulation with visualisation of proton tracks
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reaching the detector run:
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XrayTel opengl.mac for OpenGL display
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XrayTel vrml.mac for VRML display and output file
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XrayTel dawn.mac for dawn display and PS output file
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To execute a run without visualisation
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XrayTel test.mac
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If the Lizard analysis options are set, histograming windows will
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automatically open and the corresponding files will be created.
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A 2D histogram (scatter plot) will display in real time every proton
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hit that reaches the detector.
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A 1D histogram will display the energy distribution of the protons
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that reach the detector at the end of the run.
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The final energy and (x,y,z) position of the protons that reach the
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detector is output to a file "detector.hits". This file is created
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if it does not exist or appended to if it does.
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3. Detector description
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The telescope and detector geometry is defined in
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XrayTelDetectorConstruction.cc
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4. Physics processes
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The physics processes are in XrayTelPhysicsList.cc
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The main process in this example is MultipleScattering of the protons
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on the mirror surfaces.
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5. Event generation
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This is done using the new General Particle Source. Documentation for
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this can be found in
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http://www.space.dera.gov.uk/space_env/gspm.html
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6. Analysis
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At present the analysis package implemented is Lizard. As this is still
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under development only simple histograming is used. The main purpose of
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including this facility was to provide the basis for the implementation of
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AIDA interfaces between Geant4 and analysis packages, in particular
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Lizard, OpenScientist and JAS. More complex analysis features may be
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implemented in future releases.
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The current implementation of the analysis class is very preliminary
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and new tags of this example are anticipated to be released soon after
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the general release
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Lizard is not currently implemented on platforms other than Linux.
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To build and execute the example on other platforms the analysis
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environment variables must not be set, except for G4ANALYSIS_BUILD
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which is required for building the executable.
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