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0001 \page ExampleTestEm13 Example TestEm13
0002
0003 How to compute cross sections from the transmition coefficient.
0004
0005 ## GEOMETRY DEFINITION
0006
0007 It is a single box representing a layer of finite thickness of
0008 homogeneous material.
0009 Two parameters define the geometry :
0010 - the material of the box,
0011 - the (full) size of the box.
0012
0013 The default geometry (1 cm of water) is constructed in
0014 DetectorConstruction, but the above parameters can be changed
0015 interactively via the commands defined in DetectorMessenger.
0016
0017 ## PHYSICS LIST
0018
0019 The physics list contains the standard electromagnetic processes.
0020 In order not to introduce 'artificial' constraints on the step size, the
0021 multiple scattering is not instanciated, and all processes are
0022 registered as discrete : there is no continuous energy loss.
0023
0024 ## AN EVENT : THE PRIMARY GENERATOR
0025
0026 The primary kinematic consists of a single particle starting at the edge
0027 of the box. The type of the particle and its energy are set in
0028 PrimaryGeneratorAction (1 MeV gamma), and can be changed via the G4
0029 build-in commands of G4ParticleGun class (see the macros provided with
0030 this example).
0031
0032 ## PHYSICS
0033
0034 An event is killed at the first step of the incident paticle.
0035 Either the particle has interacted or is transmitted through the layer.
0036 The cross section, also called absorption coefficient, is computed from
0037 the rate of unaltered transmitted incident particles.
0038
0039 The result is compared with the 'input' data, i.e. with the cross
0040 sections stored in the PhysicsTables and used by Geant4.
0041
0042 A set of macros defining various run conditions are provided.
0043 The processes are actived/inactived in order to survey the processes
0044 individually.
0045
0046
0047 ## VISUALIZATION
0048
0049 The Visualization Manager is set in the main().
0050 The initialisation of the drawing is done via the commands
0051 /vis/... in the macro vis.mac. To get visualisation:
0052 ```
0053 > /control/execute vis.mac
0054 ```
0055
0056 The detector has a default view which is a longitudinal view of the
0057 box.
0058
0059 The tracks are drawn at the end of event, and erased at the end of run.
0060
0061 ## HOW TO START ?
0062
0063 - Execute TestEm13 in 'batch' mode from macro files :
0064 ```
0065 % ./TestEm13 compt.mac
0066 ```
0067
0068 - Execute TestEm13 in 'interactive mode' with visualization :
0069 ```
0070 % ./TestEm13
0071 Idle> control/execute vis.mac
0072 ....
0073 Idle> type your commands
0074 ....
0075 Idle> exit
0076 ```
0077
0078 Macros provided in this example:
0079 - anni.mac: e+ (10 MeV) on 5 cm Aluminium
0080 - compton.mac: gamma (300 keV) on 1 cm Aluminium
0081 - conv.mac: gamma (20 MeV) on 5 mm Lead
0082 - electron.mac: e- (100 MeV) on 1 cm Aluminium
0083 - gamma.mac: gamma (100 keV) on 1 cm Water
0084 - photoelec.mac: gamma (100 keV) on 1 cm Iron
0085 - proton.mac: proton (1 GeV) on 1 cm Water
0086
