| Geant4 Cross Reference |
>> 1 $Id: README,v 1.13 2005/11/30 19:58:30 santin Exp $
1 ---------------------------------------------- 2 -------------------------------------------------------------------
2 3
3 ========================================= 4 =========================================================
4 Geant4 - X-Ray Telescope Exampl 5 Geant4 - X-Ray Telescope Example
5 ========================================= 6 =========================================================
6 7
7 8
>> 9 NEW: May 2004: Migration to AIDA 3.2.1 - see below
>> 10
>> 11
8 Introduction 12 Introduction
9 ------------ 13 ------------
10 XrayTel is an advanced Geant4 example based on 14 XrayTel is an advanced Geant4 example based on a realistic simulation of
11 an X-ray Telescope. It is based on work carri 15 an X-ray Telescope. It is based on work carried out by a team of Geant4
12 experts to simulate the interaction between X- 16 experts to simulate the interaction between X-ray Telescopes XMM-Newton
13 and Chandra with low energy protons present in 17 and Chandra with low energy protons present in the orbital radiation
14 background. The X-ray mirrors are designed to 18 background. The X-ray mirrors are designed to collect x-ray photons at
15 grazing-incidence angles and focus them onto d 19 grazing-incidence angles and focus them onto detectors at the focal plane.
16 However, this mechanism also seems to work for 20 However, this mechanism also seems to work for low energy protons which,
17 if they reach the detectors in sufficient numb 21 if they reach the detectors in sufficient numbers, can cause damage.
18 In this example, the geometry has been simplif 22 In this example, the geometry has been simplified by using a single mirror
19 shell and no baffles, but all the dimensions a 23 shell and no baffles, but all the dimensions and materials are realistic.
20 24
21 The aim of this advanced example is to illustr 25 The aim of this advanced example is to illustrate the use advanced
22 GUI, visualisation, particle generation and an 26 GUI, visualisation, particle generation and analysis schemes available
23 in Geant4: 27 in Geant4:
24 28
>> 29 - the simulation can be run from GAG or the command prompt
>> 30
25 - macros are provided to display the geometry 31 - macros are provided to display the geometry and particle tracks with
26 OpenGL, DAWN Postscript or VRML visualisati 32 OpenGL, DAWN Postscript or VRML visualisation
27 33
28 - the generation of particles is done via the 34 - the generation of particles is done via the new General Particle Source
29 35
30 - histograming facilities are available throu << 36 - histograming facilities are available through the AIDA 3.0 interfaces.
>> 37
>> 38 - on-line visualisation of histograms is provided through the AIDA 3.0 interface.
31 39
32 In order to be able to use any of these packag 40 In order to be able to use any of these packages, prior installation is
33 necessary and a number of environment variable 41 necessary and a number of environment variables will have to be set.
34 42
35 43
>> 44 1. Setting up the environment variables for GAG, Visualisation and
>> 45 Analysis options (example based on Linux at CERN)
>> 46
>> 47 #set up GAG
>> 48 setenv G4UI_BUILD_GAG_SESSION 1
>> 49 setenv G4UI_USE_GAG 1
>> 50
>> 51 #set up VRMLview
>> 52 setenv G4VIS_USE_VRML 1
>> 53 setenv G4VRMLFILE_MAX_FILE_NUM 100
>> 54 setenv G4VRMLFILE_VIEWER vrmlview #if installed
>> 55 setenv G4VIS_USE_VRML 1
>> 56 setenv PATH ${PATH}:"/afs/cern.ch/sw/contrib/VRML/bin/Linux" # example at CERN
>> 57
>> 58 #set up OpenGL
>> 59 setenv G4VIS_BUILD_OPENGLX_DRIVER 1
>> 60 setenv G4VIS_USE_OPENGLX 1
>> 61
>> 62 #set up DAWN
>> 63 setenv G4VIS_BUILD_DAWN_DRIVER 1
>> 64 setenv G4VIS_USE_DAWN 1
>> 65
36 NOTE: The geometry is refreshed on the viewer 66 NOTE: The geometry is refreshed on the viewer at the beginning of each run,
37 but the tracks are plotted only in case 67 but the tracks are plotted only in case an interesting event occurs.
38 This is the case only for about 1 every 68 This is the case only for about 1 every 10**4 events.
39 69
40 70
41 71
>> 72 Sources
>> 73 -------
>> 74
>> 75 GAG can be found in:
>> 76
>> 77 geant4/environments/MOMO
>> 78
>> 79 DAWN can be obtained from:
>> 80
>> 81 http://geant4.kek.jp/~tanaka/
>> 82
>> 83 VRMLview for Linux can be obtained from:
>> 84
>> 85 http://www.sim.no
>> 86
>> 87
42 2. Run 88 2. Run
43 89
44 To execute a sample simulation with visualisat 90 To execute a sample simulation with visualisation of proton tracks
45 reaching the detector run: 91 reaching the detector run:
46 92
47 XrayTel 93 XrayTel
48 94
49 execute command "/control/execute test.mac" << 95 execute command "/control/execute xxxxx.mac"
>> 96
>> 97 visualisation macros provided are
>> 98 - opengl.mac for OpenGL display
>> 99 - vrml.mac for VRML display and output file
>> 100 - dawn.mac for dawn display and PS output file
>> 101
>> 102 To execute a run without visualisation use
>> 103 - test.mac
50 104
51 To enable visualisation, uncomment one line fr <<
52 /control/execute vis.mac <<
53 105
54 If the analysis options are set, histograms wi << 106 If the analysis options are set, histograming windows will
55 automatically created and the corresponding fi << 107 automatically open and the corresponding files will be created.
56 A 1D histogram will display the energy distrib 108 A 1D histogram will display the energy distribution of the protons
57 that reach the detector at the end of the run. 109 that reach the detector at the end of the run.
58 110
59 111
60 3. Detector description 112 3. Detector description
61 113
62 The telescope and detector geometry is defined 114 The telescope and detector geometry is defined in
63 XrayTelDetectorConstruction.cc 115 XrayTelDetectorConstruction.cc
64 116
65 117
66 4. Physics processes 118 4. Physics processes
67 119
68 The physics processes are in XrayTelPhysicsLis 120 The physics processes are in XrayTelPhysicsList.cc
69 The main process in this example is G4hMultipl << 121 The main process in this example is MultipleScattering of the protons
70 off the mirror surfaces. << 122 on the mirror surfaces.
71 123
72 124
73 5. Event generation 125 5. Event generation
74 126
75 This is done using the new General Particle So 127 This is done using the new General Particle Source. Documentation for
76 this can be found in: 128 this can be found in:
77 129
78 http://reat.space.qinetiq.com/gps/ 130 http://reat.space.qinetiq.com/gps/
79 131
80 132
81 6. Analysis 133 6. Analysis
82 134
83 Relevant information from the simulation is pr << 135 In case the variable G4ANALYSIS_USE is set:
84 class and saved, through the G4AnalysisManager << 136 setenv G4ANALYSIS_USE 1
85 Tuples. The output file is written in Root for << 137 relevant information from the simulation is processed in the XrayTelAnalysis
86 No external software is required (apart from t << 138 class and saved, through the AIDA interface, to Histograms and Tuples.
>> 139
>> 140 Compilation and link flags to hook any AIDA compliant system are passed
>> 141 to the Geant4 GNUmakefile system by using the "aida-config" tool
>> 142 that should come with any AIDA compliant system.
>> 143 Specifically in the GNUmakefile you find the 2 lines:
>> 144 CPPFLAGS += `aida-config --include`
>> 145 LDFLAGS += `aida-config --lib`
>> 146
>> 147 For more information about AIDA and PI please look at:
>> 148 http://aida.freehep.org/
>> 149 http://www.cern.ch/PI
>> 150
>> 151 Presently, the tools
>> 152 - PI (http://cern.ch/pi)
>> 153 - OpenScientist (http://openscientist.lal.in2p3.fr/)
>> 154 - JAS (http://jas.freehep.org/jas3/)
>> 155 provide an implementation of AIDA 3.2.1
>> 156
>> 157 To build and execute the example on platforms where there is no
>> 158 implementation of the analysis system, the environment variables
>> 159 must not be set.
87 160