1 | $Id: README,v 1.14 2009/11/20 18:08:53 santin Exp $ |
---|
2 | ------------------------------------------------------------------- |
---|
3 | |
---|
4 | ========================================================= |
---|
5 | Geant4 - X-Ray Telescope Example |
---|
6 | ========================================================= |
---|
7 | |
---|
8 | |
---|
9 | Introduction |
---|
10 | ------------ |
---|
11 | XrayTel is an advanced Geant4 example based on a realistic simulation of |
---|
12 | an X-ray Telescope. It is based on work carried out by a team of Geant4 |
---|
13 | experts to simulate the interaction between X-ray Telescopes XMM-Newton |
---|
14 | and Chandra with low energy protons present in the orbital radiation |
---|
15 | background. The X-ray mirrors are designed to collect x-ray photons at |
---|
16 | grazing-incidence angles and focus them onto detectors at the focal plane. |
---|
17 | However, this mechanism also seems to work for low energy protons which, |
---|
18 | if they reach the detectors in sufficient numbers, can cause damage. |
---|
19 | In this example, the geometry has been simplified by using a single mirror |
---|
20 | shell and no baffles, but all the dimensions and materials are realistic. |
---|
21 | |
---|
22 | The aim of this advanced example is to illustrate the use advanced |
---|
23 | GUI, visualisation, particle generation and analysis schemes available |
---|
24 | in Geant4: |
---|
25 | |
---|
26 | - macros are provided to display the geometry and particle tracks with |
---|
27 | OpenGL, DAWN Postscript or VRML visualisation |
---|
28 | |
---|
29 | - the generation of particles is done via the new General Particle Source |
---|
30 | |
---|
31 | - histograming facilities are available through the AIDA 3.0 interfaces. |
---|
32 | |
---|
33 | - on-line visualisation of histograms is provided through the AIDA 3.0 interface. |
---|
34 | |
---|
35 | In order to be able to use any of these packages, prior installation is |
---|
36 | necessary and a number of environment variables will have to be set. |
---|
37 | |
---|
38 | |
---|
39 | NOTE: The geometry is refreshed on the viewer at the beginning of each run, |
---|
40 | but the tracks are plotted only in case an interesting event occurs. |
---|
41 | This is the case only for about 1 every 10**4 events. |
---|
42 | |
---|
43 | |
---|
44 | |
---|
45 | 2. Run |
---|
46 | |
---|
47 | To execute a sample simulation with visualisation of proton tracks |
---|
48 | reaching the detector run: |
---|
49 | |
---|
50 | XrayTel |
---|
51 | |
---|
52 | execute command "/control/execute xxxxx.mac" |
---|
53 | |
---|
54 | visualisation macros provided are |
---|
55 | - opengl.mac for OpenGL display |
---|
56 | - vrml.mac for VRML display and output file |
---|
57 | - dawn.mac for dawn display and PS output file |
---|
58 | |
---|
59 | To execute a run without visualisation use |
---|
60 | - test.mac |
---|
61 | |
---|
62 | |
---|
63 | If the analysis options are set, histograming windows will |
---|
64 | automatically open and the corresponding files will be created. |
---|
65 | A 1D histogram will display the energy distribution of the protons |
---|
66 | that reach the detector at the end of the run. |
---|
67 | |
---|
68 | |
---|
69 | 3. Detector description |
---|
70 | |
---|
71 | The telescope and detector geometry is defined in |
---|
72 | XrayTelDetectorConstruction.cc |
---|
73 | |
---|
74 | |
---|
75 | 4. Physics processes |
---|
76 | |
---|
77 | The physics processes are in XrayTelPhysicsList.cc |
---|
78 | The main process in this example is G4hMultipleScattering for scattering of the protons |
---|
79 | off the mirror surfaces. |
---|
80 | |
---|
81 | |
---|
82 | 5. Event generation |
---|
83 | |
---|
84 | This is done using the new General Particle Source. Documentation for |
---|
85 | this can be found in: |
---|
86 | |
---|
87 | http://reat.space.qinetiq.com/gps/ |
---|
88 | |
---|
89 | |
---|
90 | 6. Analysis |
---|
91 | |
---|
92 | In case the variable G4ANALYSIS_USE is set: |
---|
93 | setenv G4ANALYSIS_USE 1 |
---|
94 | relevant information from the simulation is processed in the XrayTelAnalysis |
---|
95 | class and saved, through the AIDA interface, to Histograms and Tuples. |
---|
96 | |
---|
97 | Compilation and link flags to hook any AIDA compliant system are passed |
---|
98 | to the Geant4 GNUmakefile system by using the "aida-config" tool |
---|
99 | that should come with any AIDA compliant system. |
---|
100 | Specifically in the GNUmakefile you find the 2 lines: |
---|
101 | CPPFLAGS += `aida-config --include` |
---|
102 | LDFLAGS += `aida-config --lib` |
---|
103 | |
---|
104 | For more information about AIDA please look at: |
---|
105 | http://aida.freehep.org/ |
---|
106 | |
---|
107 | Presently, tools |
---|
108 | - OpenScientist (http://openscientist.lal.in2p3.fr/) |
---|
109 | - JAS (http://jas.freehep.org/jas3/) |
---|
110 | - iAIDA (http://iaida.dynalias.net/Intro.html) |
---|
111 | provide an implementation of AIDA 3.2.1 |
---|
112 | |
---|
113 | To build and execute the example on platforms where there is no |
---|
114 | implementation of the analysis system, the environment variables |
---|
115 | must not be set. |
---|
116 | |
---|