source: trunk/examples/extended/polarisation/Pol01/README @ 1309

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1$Id: README,v 1.2 2007/12/04 10:34:17 schaelic Exp $
2-------------------------------------------------------------------
3
4     =========================================================
5     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
6     =========================================================
7
8                            TestPolarization
9                            ----------------
10
11        How to compute and plot the QED processes including
12        polarization.
13        Two possible scenarios are available:
14        - Polarization transfer of an incoming beam to final state particles
15        - Material dependent transmission of a polarized beams.
16        The method is explained below : see item Physics.
17       
18 1- GEOMETRY DEFINITION
19 
20        The geometry consists of a single block of a homogeneous material,
21        placed in a world.
22       
23        Three parameters define the geometry :
24        - the material of the box,
25        - the thickness of the box (sizeZ),
26        - the  transverse dimension of the box (sizeXY).
27       
28        The default geometry (5mm of Iron, G4_Fe) is constructed in
29        DetectorConstruction, but the above parameters can be changed
30        interactively via the commands defined in DetectorMessenger.
31        Its polarization can be accessed via the PolarizationMessenger
32        (see example macro file), and is given in the global coordinate
33        system.
34       
35 2- PHYSICS LIST
36 
37        The Physics List contains QED particle definitions (electrons,
38        positrons and photons) and a general transportation process.
39        In addition the user can add one of the two process modules:
40         1. "standard"  - standard (unpolarized) EM physics
41         2. "polarized" - polarized EM physics
42        These physics list contain the standard electromagnetic processes.
43         
44 3- AN EVENT : THE PRIMARY GENERATOR
45 
46        The primary kinematic consists of a single particle starting
47        at the edge of the box. The type of the particle and its
48        energy are set in PrimaryGeneratorAction (10 MeV electron).
49        By default the ParticleGun polarization is zero.
50        All parameter can be changed via the G4 build-in commands of
51        ParticleGun class (see the macros provided with this example).
52       
53 4- PHYSICS
54 
55     This example uses the following physics processes:
56
57       - electromagnetic:
58           photo-electric effect
59           Compton scattering
60           pair production
61           bremsstrahlung
62           ionization
63           multiple scattering
64           annihilation
65       or
66       - polarized electromagnetic:
67         (incl. simulation of polarization transfer, and
68          asymmetries for longitudinally polarized leptons, and
69          circularly polarized photons)
70
71           polarized photo-electric effect
72           polarized Compton scattering
73           polarized pair production
74           polarized bremsstrahlung
75           polarized ionization
76           multiple scattering
77           polarized annihilation
78       and
79       - transportation
80
81     and defines the following particles:
82        electron, positron, photon
83
84
85 5- HISTOGRAMS
86         
87        The test contains 12 built-in 1D histograms, which are managed by the
88        HistoManager class and its Messenger. The histos can be individually
89        activated with the command :
90        /testem/histo/setHisto id nbBins  valMin valMax unit
91        where unit is the desired unit for the histo (MeV or keV, etc..)
92        (see the macro histos.mac).
93
94            1  gamma energy
95            2  gamma cos(theta)
96            3  gamma phi
97            4  gamma polarization
98            5  electron energy
99            6  electron cos(theta)
100            7  electron phi
101            8  electron polarization
102            9  positron energy
103           10 positron cos(theta)
104           11 positron phi
105           12 positron polarization
106
107        If AIDA is available, i.e. if G4ANALYSIS_USE is set, these
108        histograms are stored in a compressed XML file
109        (pol01.aida). These results can be displayed using a small
110        program (plotResults.java) based on JAIDA by simply calling
111
112          % gmake plots
113                                       
114 6- VISUALIZATION
115 
116     Simulated events can be displayed on top of a representation of
117     the geometry, see vis.mac for an example.
118       
119 7- HOW TO START ?
120 
121        compile and link to generate an executable
122                % gmake
123               
124        execute pol01 in 'batch' mode from the default macro file :
125                % pol01   pol01.in
126
127        or execute pol01 in 'batch' mode including aida output :
128                % pol01   histos.mac
129
130        if available use JAIDA to display the results via
131                % gmake plots
132
133        a visualisation example is available by calling
134                % pol01 
135                [...]
136                PreInit> /control/execute vis.mac
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