| Geant4 Cross Reference |
>> 1 $Id: README,v 1.17 2008-09-18 16:42:07 maire Exp $
1 ---------------------------------------------- 2 -------------------------------------------------------------------
2 3
3 ========================================= 4 =========================================================
4 Geant4 - an Object-Oriented Toolkit for S 5 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
5 ========================================= 6 =========================================================
6 7
7 TestEm6 8 TestEm6
8 ------- 9 -------
9 This example is intended to test the proc 10 This example is intended to test the processes of gamma conversion
10 to a pair of muons and annihilation of po 11 to a pair of muons and annihilation of positrons with atomic
11 electrons to a pair of muons. 12 electrons to a pair of muons.
>> 13 To make these process more visible, the usually much more frequent
>> 14 gamma conversion to a pair of electrons and the standard positron
>> 15 processes are not selected in the physics list.
12 16
13 1- GEOMETRY DEFINITION 17 1- GEOMETRY DEFINITION
14 18
15 The geometry consists of a single block o 19 The geometry consists of a single block of a homogenous material.
16 20
17 Two parameters define the geometry : 21 Two parameters define the geometry :
18 - the material of the box, << 22 - the material of the box,
19 - the (full) size of the box. << 23 - the (full) size of the box.
20 The default is 500 m of iron. 24 The default is 500 m of iron.
21 25
22 In addition a transverse uniform magnetic 26 In addition a transverse uniform magnetic field can be applied.
23 27
24 The default geometry is constructed in De 28 The default geometry is constructed in DetectorConstruction class,
25 but all of the above parameters can be ch 29 but all of the above parameters can be changed interactively via
26 the commands defined in the DetectorMesse 30 the commands defined in the DetectorMessenger class.
27 31
28 2- PHYSICS LIST 32 2- PHYSICS LIST
29 << 33
30 Physics Lists are based on modular design << 34 The particle list is the one of novice/exampleN03.
31 instantiated: << 35 The physics list contains the 'standard' electromagnetic processes,
32 1. Transportation << 36 and decay.
33 2. EM physics << 37
34 3. Decays << 38 For Gamma, only the GammaConversionToMuons has been registered.
35 4. StepMax - for step limitation << 39 Futhermore, a high production cut (1 km, which gives infinity in energy)
36 << 40 prevent any production of delta-electrons from ionization or gamma
37 The electromagnetic physics is chosen fro << 41 from bremsstrahlung.
38 physics constructors in the physics_list << 42 For Positrons, only the annihilation process is selected.
39 << 43
40 Cross sections can be enhanced (see below <<
41 44
42 3- AN EVENT : THE PRIMARY GENERATOR 45 3- AN EVENT : THE PRIMARY GENERATOR
43 46
44 The primary kinematic consists of a singl 47 The primary kinematic consists of a single particle which hits the
45 block perpendicular to the input face. Th 48 block perpendicular to the input face. The type of the particle
46 and its energy are set in the PrimaryGene 49 and its energy are set in the PrimaryGeneratorAction class, and can
47 changed via the G4 build-in commands of G << 50 changed via the G4 build-in commands of ParticleGun class (see
48 the macros provided with this example). 51 the macros provided with this example).
49 The default is a Gamma of 100 TeV. 52 The default is a Gamma of 100 TeV.
50 53
51 In addition one can choose randomly the i 54 In addition one can choose randomly the impact point of the incident
52 particle. The corresponding interactive c 55 particle. The corresponding interactive command is built in
53 PrimaryGeneratorMessenger class. 56 PrimaryGeneratorMessenger class.
54 57
55 A RUN is a set of events. 58 A RUN is a set of events.
>> 59
56 60
57 4- VISUALIZATION 61 4- VISUALIZATION
58 62
59 The Visualization Manager is set in the m << 63 The Visualization Manager is set in the main().
60 The initialisation of the drawing is done 64 The initialisation of the drawing is done via the command
61 > /control/execute vis.mac 65 > /control/execute vis.mac
62 66
63 The detector has a default view which is 67 The detector has a default view which is a longitudinal view of the box.
64 68
65 The tracks are drawn at the end of event, 69 The tracks are drawn at the end of event, and erased at the end of run.
66 Optionally one can choose to draw all par << 70 Optionaly one can choose to draw all particles, only the charged one,
67 or none. This command is defined in Event 71 or none. This command is defined in EventActionMessenger class.
68 72
69 5- PHYSICS DEMO 73 5- PHYSICS DEMO
70 74
71 The particle's type and the physics proce << 75 The particle's type and the physic processes which will be available
72 in this example are set in PhysicsList cl 76 in this example are set in PhysicsList class.
73 77
74 In addition a build-in interactive comman << 78 In addition a build-in interactive command (/process/inactivate proname)
75 allows to activate/inactivate the process 79 allows to activate/inactivate the processes one by one.
76 80
77 The threshold for producing secondaries c 81 The threshold for producing secondaries can be changed.
78 eg: /run/particle/setCut 100 micrometer 82 eg: /run/particle/setCut 100 micrometer
79 /run/initialize 83 /run/initialize
80 << 84
81 To visualize the GammaConversionToMuons : 85 To visualize the GammaConversionToMuons :
82 /control/execute run01.mac 86 /control/execute run01.mac
83 /control/execute vis.mac << 87 /control/execute vis.mac
84 /run/beamOn << 88 /run/beamOn
85 << 89
86 To visualize the AnnihiToMuPair : 90 To visualize the AnnihiToMuPair :
87 /control/execute run11.mac 91 /control/execute run11.mac
88 /control/execute vis.mac << 92 /control/execute vis.mac
89 /run/beamOn << 93 /run/beamOn
90 << 94
91 Other macros: <<
92 - run02.mac: the final state of the Gamma <<
93 - run12.mac: test on carbon target with b <<
94 <<
95 6- HOW TO START ? 95 6- HOW TO START ?
96 96
>> 97 - compile and link to generate an executable
>> 98 % cd geant4/examples/extended/electromagnetic/TestEm6
>> 99 % gmake
>> 100
97 - execute Test in 'batch' mode from macr 101 - execute Test in 'batch' mode from macro files
98 % TestEm6 run01.mac 102 % TestEm6 run01.mac
99 103
100 - execute Test in 'interactive mode' wit 104 - execute Test in 'interactive mode' with visualization
101 % TestEm6 105 % TestEm6
102 .... 106 ....
103 Idle> type your commands 107 Idle> type your commands
104 .... 108 ....
105 Idle> exit 109 Idle> exit
106 110
107 7- HOW TO INCREASE STATISTICS ON gamma -> mu+ 111 7- HOW TO INCREASE STATISTICS ON gamma -> mu+mu- ?
108 112
109 The processes of gamma -> mu+mu- and e+e 113 The processes of gamma -> mu+mu- and e+e- -> mu+mu-
110 have a low cross section but can be impor 114 have a low cross section but can be important
111 for leakage through thick absorbers and c 115 for leakage through thick absorbers and calorimeters.
112 Straight forward simulation will be quite 116 Straight forward simulation will be quite time consuming.
113 To make the processes more visible, the c 117 To make the processes more visible, the cross section can be
114 artificially increased by some factor (he 118 artificially increased by some factor (here 1000)
115 using the commands (only effective after 119 using the commands (only effective after /run/initialize)
116 120
117 /testem/phys/SetGammaToMuPairFac 1000 121 /testem/phys/SetGammaToMuPairFac 1000
118 /testem/phys/SetAnnihiToMuPairFac 1000 122 /testem/phys/SetAnnihiToMuPairFac 1000
119 123
120 124
121 8- HISTOGRAMS 125 8- HISTOGRAMS
122 126
123 Testem6 produces 6 histograms, h1 - h6, whic << 127 Testem6 produces 6 histograms which illustrate the final state of
124 the final state of the GammaConversionToMuon << 128 the GammaConversionToMuons process. See their definitions in RunAction.cc
125 with run02.mac and can be displayed with the <<
126 129
127 The remaining histograms h7 - h16 show vario << 130 By default the histograms are not activated. To activate histograms
128 of eeToHadr/eeToMu, see their definitions in << 131 the environment variable G4ANALYSIS_USE should be defined. For instance
>> 132 uncomment the flag G4ANALYSIS_USE in GNUmakefile.
>> 133
>> 134 Before compilation of the example it is optimal to clean up old files:
>> 135 gmake histclean
>> 136 gmake
129 137
130 By default the histograms are saved as teste 138 By default the histograms are saved as testem6.root
>> 139 It is possible to choose the format of the histogram file (hbook, root, XML):
>> 140 comment/uncomment 1 line in the constructor of RunAction.
131 141
132 The format of the histogram file can be : ro << 142 To use histograms, at least one of the AIDA implementations should be
133 by selecting the analysis manager default fi << 143 available. See InstallAida.txt