Warning, /geant4/examples/extended/electromagnetic/TestEm6/README.md is written in an unsupported language. File is not indexed.
0001 \page ExampleTestEm6 Example TestEm6
0002
0003 This example is intended to test the processes of gamma conversion
0004 to a pair of muons and annihilation of positrons with atomic
0005 electrons to a pair of muons.
0006
0007 ## GEOMETRY DEFINITION
0008
0009 The geometry consists of a single block of a homogenous material.
0010
0011 Two parameters define the geometry :
0012 - the material of the box,
0013 - the (full) size of the box.
0014 The default is 500 m of iron.
0015
0016 In addition a transverse uniform magnetic field can be applied.
0017
0018 The default geometry is constructed in DetectorConstruction class,
0019 but all of the above parameters can be changed interactively via
0020 the commands defined in the DetectorMessenger class.
0021
0022 ## PHYSICS LIST
0023
0024 Physics Lists are based on modular design. Several modules are
0025 instantiated:
0026 1. Transportation
0027 2. EM physics
0028 3. Decays
0029 4. StepMax - for step limitation
0030
0031 The electromagnetic physics is chosen from one of the Geant4 EM
0032 physics constructors in the physics_list library.
0033
0034 Cross sections can be enhanced (see below).
0035
0036 ## AN EVENT : THE PRIMARY GENERATOR
0037
0038 The primary kinematic consists of a single particle which hits the
0039 block perpendicular to the input face. The type of the particle
0040 and its energy are set in the PrimaryGeneratorAction class, and can
0041 changed via the G4 build-in commands of G4ParticleGun class (see
0042 the macros provided with this example).
0043 The default is a Gamma of 100 TeV.
0044
0045 In addition one can choose randomly the impact point of the incident
0046 particle. The corresponding interactive command is built in
0047 PrimaryGeneratorMessenger class.
0048
0049 A RUN is a set of events.
0050
0051 ## VISUALIZATION
0052
0053 The Visualization Manager is set in the main().
0054 The initialisation of the drawing is done via the command
0055 ```
0056 > /control/execute vis.mac
0057 ```
0058
0059 The detector has a default view which is a longitudinal view of the box.
0060
0061 The tracks are drawn at the end of event, and erased at the end of run.
0062 Optionally one can choose to draw all particles, only the charged ones,
0063 or none. This command is defined in EventActionMessenger class.
0064
0065 ## PHYSICS DEMO
0066
0067 The particle's type and the physics processes which will be available
0068 in this example are set in PhysicsList class.
0069
0070 In addition a build-in interactive command (/process/inactivate procname)
0071 allows to activate/inactivate the processes one by one.
0072
0073 The threshold for producing secondaries can be changed.
0074 eg:
0075 ```
0076 /run/particle/setCut 100 micrometer
0077 /run/initialize
0078 ```
0079
0080 To visualize the GammaConversionToMuons :
0081 ```
0082 /control/execute run01.mac
0083 /control/execute vis.mac
0084 /run/beamOn
0085 ```
0086
0087 To visualize the AnnihiToMuPair :
0088 ```
0089 /control/execute run11.mac
0090 /control/execute vis.mac
0091 /run/beamOn
0092 ```
0093
0094 Other macros:
0095 - run02.mac: the final state of the GammaConversionToMuons
0096 - run12.mac: test on carbon target with biasing of cross section
0097
0098 ## HOW TO START ?
0099
0100 - Execute Test in 'batch' mode from macro files
0101 ```
0102 % ./TestEm6 run01.mac
0103 ```
0104
0105 - Execute Test in 'interactive mode' with visualization
0106 ```
0107 % ./TestEm6
0108 ....
0109 Idle> type your commands
0110 ....
0111 Idle> exit
0112 ```
0113
0114 ## HOW TO INCREASE STATISTICS ON gamma -> mu+mu- ?
0115
0116 The processes of gamma -> mu+mu- and e+e- -> mu+mu-
0117 have a low cross section but can be important
0118 for leakage through thick absorbers and calorimeters.
0119 Straight forward simulation will be quite time consuming.
0120 To make the processes more visible, the cross section can be
0121 artificially increased by some factor (here 1000)
0122 using the commands (only effective after /run/initialize)
0123
0124 ```
0125 /testem/phys/SetGammaToMuPairFac 1000
0126 /testem/phys/SetAnnihiToMuPairFac 1000
0127 ```
0128
0129
0130 ## HISTOGRAMS
0131
0132 Testem6 produces 6 histograms, h1 - h6, which illustrate
0133 the final state of the GammaConversionToMuons. The histograms are produced
0134 with run02.mac and can be displayed with the ROOT macro plotHisto.C.
0135
0136 The remaining histograms h7 - h16 show various cross sections and h17 the ratio
0137 of eeToHadr/eeToMu, see their definitions in RunAction.cc
0138
0139 By default the histograms are saved as testem6.root
0140
0141 The format of the histogram file can be : root (default), xml, csv,
0142 by selecting the analysis manager default file type in RunAction.cc
0143
