| Geant4 Cross Reference |
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4 Geant4 - an Object-Oriented Toolkit for S
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6
7 TestPolarization
8 ----------------
9
10 How to compute and plot the QED processes in
11 polarization.
12 Two possible scenarios are available:
13 - Polarization transfer of an incoming beam
14 - Material dependent transmission of a polar
15 The method is explained below : see item Phy
16
17 1- GEOMETRY DEFINITION
18
19 The geometry consists of a single block of a
20 placed in a world.
21
22 Three parameters define the geometry :
23 - the material of the box,
24 - the thickness of the box (sizeZ),
25 - the transverse dimension of the box (size
26
27 The default geometry (5mm of Iron, G4_
28 DetectorConstruction, but the above paramete
29 interactively via the commands defined in De
30 Its polarization can be accessed via t
31 (see example macro file), and is given
32 system.
33
34 2- PHYSICS LIST
35
36 The Physics List contains QED particle defin
37 positrons and photons) and a general t
38 In addition the user can add one of th
39 1. "standard" - standard (unpolarized) EM
40 2. "polarized" - polarized EM physics
41 These physics list contain the standard elec
42
43 3- AN EVENT : THE PRIMARY GENERATOR
44
45 The primary kinematic consists of a single p
46 at the edge of the box. The type of th
47 energy are set in PrimaryGeneratorActi
48 By default the ParticleGun polarizatio
49 All parameter can be changed via the G
50 ParticleGun class (see the macros prov
51
52 4- PHYSICS
53
54 This example uses the following physics p
55
56 - electromagnetic:
57 photo-electric effect
58 Compton scattering
59 pair production
60 bremsstrahlung
61 ionization
62 multiple scattering
63 annihilation
64 or
65 - polarized electromagnetic:
66 (incl. simulation of polarization tra
67 asymmetries for longitudinally polar
68 circularly polarized photons)
69
70 polarized photo-electric effect
71 polarized Compton scattering
72 polarized pair production
73 polarized bremsstrahlung
74 polarized ionization
75 multiple scattering
76 polarized annihilation
77 and
78 - transportation
79
80 and defines the following particles:
81 electron, positron, photon
82
83
84 5- HISTOGRAMS
85
86 The test contains 12 built-in 1D histograms,
87 HistoManager class and its Messenger. The hi
88 activated with the command :
89 /analysis/h1/set id nbBins valMin val
90 where unit is the desired unit for the histo
91 (see the macro histos.mac).
92
93 1 gamma energy
94 2 gamma cos(theta)
95 3 gamma phi
96 4 gamma polarization
97 5 electron energy
98 6 electron cos(theta)
99 7 electron phi
100 8 electron polarization
101 9 positron energy
102 10 positron cos(theta)
103 11 positron phi
104 12 positron polarization
105
106 6- VISUALIZATION
107
108 Simulated events can be displayed on top
109 the geometry, see vis.mac for an example.
110
111 7- HOW TO START ?
112
113 compile and link to generate an executable
114 % gmake
115
116 execute Pol01 in 'batch' mode from the defau
117 % Pol01 pol01.in
118
119 or execute Pol01 in 'batch' mode including a
120 % Pol01 histos.mac
121
122 if available use JAIDA to display the
123 % gmake plots
124
125 a visualisation example is available by call
126 % Pol01
127 [...]
128 PreInit> /control/execute vis.