$Id: README,v 1.9 2002/06/18 23:46:12 pia Exp $ ------------------------------------------------------------------- ========================================================= Geant4 - an Object-Oriented Toolkit for Simulation in HEP ========================================================= xray_telescope -------------- XrayTel is an advanced Geant4 example based on a realistic simulation of an X-ray Telescope. It is based on work carried out by a team of Geant4 experts to simulate the interaction between X-ray Telescopes XMM-Newton and Chandra with low energy protons present in the orbital radiation background. The X-ray mirrors are designed to collect x-ray photons at grazing-incidence angles and focus them onto detectors at the focal plane. However, this mechanism also seems to work for low energy protons which, if they reach the detectors in sufficient numbers, can cause damage. In this example, the geometry has been simplified by using a single mirror shell and no baffles, but all the dimensions and materials are realistic. The aim of this advanced example is to illustrate the use advanced GUI, visualisation, particle generation and analysis schemes available in Geant4: - the simulation can be run from GAG or the command prompt - macros are provided to display the geometry and particle tracks with OpenGL, DAWN Postscript or VRML visualisation - the generation of particles is done via the new General Particle Source - histograming facilities are available through the AIDA interfaces. The implementation shown in this example is obsolete, and will be updated in a future release; for an up-to-date illustration of how to embed an AIDA-compliant analysis in a Geant4-based simulation application, please see the other advanced examples in this Geant4 release (brachytherapy, gammaray_telescope, underground_physics, xray_fluorescence). In order to be able to use any of these packages, prior installation is necessary and a number of environment variables will have to be set. 1. Setting up the environment variables for GAG, Visualisation and Analysis options (example based on Linux at CERN) #set up GAG setenv G4UI_BUILD_GAG_SESSION 1 setenv G4UI_USE_GAG 1 #set up VRMLview setenv G4VIS_BUILD_VRMLFILE_DRIVER 1 setenv G4VIS_USE_VRML 1 setenv G4VIS_USE_VRMLFILE 1 setenv G4VRMLFILE_MAX_FILE_NUM 100 setenv G4VRMLFILE_VIEWER vrmlview #if installed setenv G4VIS_USE_VRML 1 setenv G4VIS_USE_VRMLFILE 1 setenv PATH ${PATH}:"/afs/cern.ch/sw/contrib/VRML/bin/Linux" #set up OpenGL or Mesa setenv G4VIS_BUILD_OPENGLX_DRIVER 1 setenv G4VIS_USE_OPENGLX 1 setenv OGLHOME /afs/cern.ch/sw/geant4/dev/Mesa/Linux-g++ #set up DAWN setenv G4VIS_BUILD_DAWN_DRIVER 1 setenv G4VIS_BUILD_DAWNFILE_DRIVER 1 setenv G4VIS_USE_DAWN 1 setenv G4VIS_USE_DAWNFILE 1 setenv PATH ${PATH}:"/afs/cern.ch/sw/geant4/dev/DAWN/Linux-g++" # flag that we want to use analysis: setenv G4ANALYSIS_USE 1 # select analysis system: any AIDA 2.2 compliant system or Anaphe 3.6.5 # set up for AIDA 2.2 compliancy: # Compilation and link flags to hook and AIDA compliant system # are passed to the Geant4 GNUmakefile system by using the "aida-config" tool # that should come with any AIDA compliant system. Examples are: # setenv G4ANALYSIS_AIDA_CONFIG_CFLAGS `aida-config --include` # setenv G4ANALYSIS_AIDA_CONFIG_LIBS `aida-config --libs` #set up Anaphe/Lizard for the gcc-2.95 compiler setenv G4ANALYSIS_SYSTEM Lizard setenv G4ANALYSIS_USE_LIZARD 1 setenv G4ANALYSIS_BUILD 1 setenv G4ANALYSIS_BUILD_LIZARD 1 setenv PATH ${PATH}:/afs/cern.ch/sw/lhcxx/specific/redhat61/gcc-2.95.2/3.6.5/bin source /afs/cern.ch/sw/lhcxx/share/LHCXX/3.6.5/install/sharedstart.csh #add to the LD_LIBRARY_PATH setenv LD_LIBRARY_PATH $OGLHOME/lib IMPORTANT WARNING! setenv G4ANALYSIS_BUILD 1 must always be set to build the example even if the analysis option is not required Sources ------- GAG can be obtained from http://erpc1.naruto-u.ac.jp/~geant4/ OpenGL Mesa needs to be installed prior to building Geant4 and can be downloaded from http://www.mesa3d.org/download.html DAWN can be obtained from http://133.7.51.8/dawn/ VRMLview for Linux can be obtained from 2. Run To execute a sample simulation with visualisation of proton tracks reaching the detector run: XrayTel execute command "/control/execute xxxxx.mac" visualisation macros provided are - opengl.mac for OpenGL display - vrml.mac for VRML display and output file - dawn.mac for dawn display and PS output file To execute a run without visualisation use - test.mac If the analysis options are set, histograming windows will automatically open and the corresponding files will be created. A 2D histogram (scatter plot) will display in real time every proton hit that reaches the detector. A 1D histogram will display the energy distribution of the protons that reach the detector at the end of the run. The final energy and (x,y,z) position of the protons that reach the detector is output to a file "detector.hits". This file is created if it does not exist or appended to if it does. 3. Detector description The telescope and detector geometry is defined in XrayTelDetectorConstruction.cc 4. Physics processes The physics processes are in XrayTelPhysicsList.cc The main process in this example is MultipleScattering of the protons on the mirror surfaces. 5. Event generation This is done using the new General Particle Source. Documentation for this can be found in http://www.space.dera.gov.uk/space_env/gspm.html 6. Analysis At present there are two options for analysis packages: either explicitely the Anaphe 3.6.5 (or compatible) version is selected, or any AIDA-2.2 compliant analysis system is chosen. This dual approach will be removed in the next release when only the AIDA compliant version will be present. Presently, the OpenScientist package (version 8) provides an implementation of AIDA 2.2, other packages as Anaphe and JAS will follow soon. The AIDA compliant version has not been tested by the developers and is here as a example of "forward compatibility" on how to use analysis. To build and execute the example on platforms where there is no implementation of the analysis system, the environment variables must not be set, except for G4ANALYSIS_BUILD which is required for building the executable.