| Geant4 Cross Reference |
1 ===================================== << 1 =========================================================
2 Geant4 - an Object-Oriented Toolkit f << 2 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
3 ===================================== << 3 =========================================================
4 << 4
5 WLS << 5 WLS
6 ---------- << 6 ----------
7 << 7
8 This application simulates the propagation o << 8 This application simulates the propagation of photons inside a Wave Length
9 Wave Length Shifting (WLS) fiber. << 9 Shifting (WLS) fiber.
10 << 10
11 << 11
12 1- Geometry Definition << 12 1- Geometry Definition
13 << 13
14 The default geometry is as follow: << 14 The default geometry is as follow:
15 << 15
16 - A perfect, bare (or clad), PMMA fiber: 0.5mm << 16 - A perfect, bare, PMMA fiber: 0.5mm radius, 2m length at center(0,0,0)
17 center (0,0,0) of the World. << 17 of the World.
18 - A circular MPPC with 0.5mm radius at the +z << 18 - A circular MPPC with 0.5mm radius at the +z end of the fiber
19 - World and coupling materials are G4_AIR << 19 - World and coupling materials are G4_AIR
20 - Photons will always refracted out to couplin << 20 - Photons will always refracted out to coupling material before
21 reaching MPPC << 21 reaching MPPC
22 - There are many flexible parameters that the << 22 - There are many flexible parameters that the user could specify.
23 They are under the /WLS directory of help. << 23 They are under the /WLS directory of help.
24 << 24
25 << 25
26 2- Material Choices << 26 2- Material Choices
27 << 27
28 There are several materials that the user ca << 28 There are several materials that the user can use for the fiber core,
29 world and coupling. << 29 world and coupling.
30 << 30
31 They are: << 31 They are:
32 << 32
33 - Vacuum (G4_Galactic) << 33 - Vacuum (G4_Galactic)
34 - Air (G4_AIR) << 34 - Air (G4_AIR)
35 - PMMA, refractive index n = 1.60 << 35 - PMMA, n = 1.60
36 - Pethylene, n = 1.49 << 36 - Pethylene, n = 1.49
37 - FPethylene, n = 1.42 << 37 - FPethylene, n = 1.42
38 - Polystyrene, n = 1.60 << 38 - Polystyrene, n = 1.60
39 - Silicone, n = 1.46 << 39 - Silicone, n = 1.46
40 << 40
41 << 41
42 3- Photon Source << 42 3- Photon Source
43 << 43
44 This program uses the General Particle Sourc << 44 This program uses the General Particle Source provided by GEANT4 for
45 provided by Geant4 for generating particles. << 45 generating photons. The energy of the photon must be within 2.00 eV
46 optical photon must be within the range 2.00 << 46 to 3.47 eV. For detail instruction on how to use the General Particle
47 << 47 Source, please visit their home page at:
48 << 48
49 4- Hit << 49 http://reat.space.qinetiq.com/gps/
50 << 50
51 A hit is registered when an optical photon i << 51
52 surface. Information stored in a hit includ << 52 4- Hit
53 location the optical photon is absorbed on t << 53
54 where the optical photon left the fiber, the << 54 A hit is registered when the photon is absorbed on the MPPC surface.
55 photon, and the energy of the optical photon << 55 Information stored in hit includes the local coordinate of the location
56 << 56 the photon is absorbed on the MPPC, the global coordinate where the
57 << 57 photon left the fiber and the transit time of the photon.
58 5- Stepping Action << 58
59 << 59
60 The stepping action keeps track of the numbe << 60 5- Stepping Action
61 gone through. In order to prevent infinite << 61
62 rays taking up computing time, there is a li << 62 The stepping action keeps track of the number of bounces a photon has
63 bounces that an optical photon can go throug << 63 gone through. In order to prevent infinite loop and extremely skewed
64 The default limit is 100,000. The user can << 64 rays taking up computing time, there is a limit of the number of
65 the /stepping/setBounceLimit command. A val << 65 bounces that a photon can go through before it is artificially killed.
66 limit. All optical photons artificially kil << 66 The default limit is 100,000. The user can set his/her own limit using
67 on in their UserTrackInformation. << 67 the /stepping/setBounceLimit command. A value of 0 will turn off the
68 << 68 limit. All photons artificially killed will have murderee flag turned
69 << 69 on in their UserTrackInformation.
70 6- Visualization << 70
71 << 71
72 To visualize particle trajectories, simply u << 72 6- Visualization
73 interactive mode or in your own macro. << 73
74 << 74 To visualize a photon's trajectory, simply use vis.mac macro in
75 << 75 interactive mode or in your own macro.
76 7- main() << 76
77 << 77
78 - execute wls in 'batch' mode from macro file << 78 7- main()
79 - you can enter an optional integer seed for << 79
80 % wls electron.mac (optional: enter a << 80 - compile and link to generate an executable
81 << 81 % cd wls
82 - wls in 'interactive mode' with visualizatio << 82 % make
83 % wls << 83
84 .... << 84 - execute wls in 'batch' mode from macro files
85 Idle> /control/execute << 85 - you can enter an optional integer seed for batch mode
86 Idle> /run/beamOn 1 << 86 % wls wls.in (optional: enter an integer seed here)
87 .... << 87
88 Idle> exit << 88 - wls in 'interactive mode' with visualization
89 << 89 % wls
90 8- Macros provided << 90 ....
91 << 91 Idle> /control/execute init.in
92 - electron.mac: Sets up the geometry and conf << 92 Idle> /control/execute vis.mac
93 Primary particle is a 10 MeV << 93 Idle> /run/beamOn 1
94 - vis.mac: macro for visualization; called au << 94 ....
95 given on command line. << 95 Idle> exit