polarisation/Pol01/README.md

0001 \page ExamplePol01 Example Pol01
0002
0003  How to compute and plot the QED processes including
0004  polarization.
0005  Two possible scenarios are available:
0006  - Polarization transfer of an incoming beam to final state particles
0007  - Material dependent transmission of a polarized beams.
0008  The method is explained below : see item Physics.
0009
0010 ## GEOMETRY DEFINITION
0011
0012  The geometry consists of a single block of a homogeneous material,
0013  placed in a world.
0014
0015  Three parameters define the geometry :
0016  - the material of the box,
0017  - the thickness of the box (sizeZ),
0018  - the  transverse dimension of the box (sizeXY).
0019
0020  The default geometry (5mm of Iron, G4_Fe) is constructed in
0021  DetectorConstruction, but the above parameters can be changed
0022  interactively via the commands defined in DetectorMessenger.
0023  Its polarization can be accessed via the G4PolarizationMessenger
0024  (see example macro file), and is given in the global coordinate
0025  system.
0026
0027 ## PHYSICS LIST
0028
0029  The physics list (PhysicsList) contains QED particle definitions (electrons,
0030  positrons and photons) and a general transportation process.
0031  In addition the user can add one of the two process modules:
0032   - 1. "standard"  - standard (unpolarized) EM physics
0033   - 2. "polarized" - polarized EM physics
0034
0035  These physics list contain the standard electromagnetic processes.
0036
0037 ## AN EVENT : THE PRIMARY GENERATOR
0038
0039  The primary kinematic consists of a single particle starting
0040  at the edge of the box. The type of the particle and its
0041  energy are set in PrimaryGeneratorAction (10 MeV electron).
0042  By default the G4ParticleGun polarization is zero.
0043  All parameter can be changed via the G4 build-in commands of
0044  ParticleGun class (see the macros provided with this example).
0045
0046 ## PHYSICS
0047
0048  This example uses the following physics processes:
0049    - electromagnetic:
0050      -  photo-electric effect
0051      -  Compton scattering
0052      -  pair production
0053      -  bremsstrahlung
0054      -  ionization
0055      -  multiple scattering
0056      -  annihilation
0057
0058    or
0059    - polarized electromagnetic:
0060      (incl. simulation of polarization transfer, and
0061       asymmetries for longitudinally polarized leptons, and
0062       circularly polarized photons)
0063        - polarized photo-electric effect
0064        - polarized Compton scattering
0065        - polarized pair production
0066        - polarized bremsstrahlung
0067        - polarized ionization
0068        - multiple scattering
0069        - polarized annihilation
0070
0071    and
0072    - transportation
0073
0074  and defines the following particles:
0075
0076    electron, positron, photon
0077
0078
0079 ## HISTOGRAMS
0080
0081  The test contains 12 built-in 1D histograms, which are managed by G4AnalysisManager.
0082  The histos can be individually activated with the command :
0083 ```
0084 /analysis/h1/set id nbBins  valMin valMax unit
0085 ```
0086  where unit is the desired unit for the histo (MeV or keV, etc..)
0087  (see the macro histos.mac).
0088
0089   -  1  gamma energy
0090   -  2  gamma cos(theta)
0091   -  3  gamma phi
0092   -  4  gamma polarization
0093   -  5  electron energy
0094   -  6  electron cos(theta)
0095   -  7  electron phi
0096   -  8  electron polarization
0097   -  9  positron energy
0098   - 10  positron cos(theta)
0099   - 11  positron phi
0100   - 12  positron polarization
0101
0102 ## VISUALIZATION
0103
0104  Simulated events can be displayed on top of a representation of
0105  the geometry, see vis.mac for an example.
0106
0107 ## HOW TO START ?
0108
0109  - Execute Pol01 in 'batch' mode from the default macro file :
0110 ```
0111 % ./Pol01   pol01.in
0112 ```
0113
0114  - Execute Pol01 in 'batch' mode including analysis output :
0115 ```
0116 % ./Pol01   histos.mac
0117 ```
0118
0119  - If available use JAIDA to display the results via
0120 ```
0121 % gmake plots
0122 ```
0123
0124  - A visualisation example is available by calling
0125 ```
0126 % ./Pol01
0127 [...]
0128 PreInit> /control/execute vis.mac
0129 ```