| Geant4 Cross Reference |
1 ---------------------------------------------- 1 -------------------------------------------------------------------
2 2
3 ========================================= 3 =========================================================
4 Geant4 - an Object-Oriented Toolkit for S 4 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
5 ========================================= 5 =========================================================
6 6
7 TestEm6 7 TestEm6
8 ------- 8 -------
9 This example is intended to test the proc 9 This example is intended to test the processes of gamma conversion
10 to a pair of muons and annihilation of po 10 to a pair of muons and annihilation of positrons with atomic
11 electrons to a pair of muons. 11 electrons to a pair of muons.
12 12
13 1- GEOMETRY DEFINITION 13 1- GEOMETRY DEFINITION
14 14
15 The geometry consists of a single block o 15 The geometry consists of a single block of a homogenous material.
16 16
17 Two parameters define the geometry : 17 Two parameters define the geometry :
18 - the material of the box, 18 - the material of the box,
19 - the (full) size of the box. 19 - the (full) size of the box.
20 The default is 500 m of iron. 20 The default is 500 m of iron.
21 21
22 In addition a transverse uniform magnetic 22 In addition a transverse uniform magnetic field can be applied.
23 23
24 The default geometry is constructed in De 24 The default geometry is constructed in DetectorConstruction class,
25 but all of the above parameters can be ch 25 but all of the above parameters can be changed interactively via
26 the commands defined in the DetectorMesse 26 the commands defined in the DetectorMessenger class.
27 27
28 2- PHYSICS LIST 28 2- PHYSICS LIST
29 29
30 Physics Lists are based on modular design 30 Physics Lists are based on modular design. Several modules are
31 instantiated: 31 instantiated:
32 1. Transportation 32 1. Transportation
33 2. EM physics 33 2. EM physics
34 3. Decays 34 3. Decays
35 4. StepMax - for step limitation 35 4. StepMax - for step limitation
36 36
37 The electromagnetic physics is chosen fro 37 The electromagnetic physics is chosen from one of the Geant4 EM
38 physics constructors in the physics_list 38 physics constructors in the physics_list library.
39 39
40 Cross sections can be enhanced (see below 40 Cross sections can be enhanced (see below).
41 41
42 3- AN EVENT : THE PRIMARY GENERATOR 42 3- AN EVENT : THE PRIMARY GENERATOR
43 43
44 The primary kinematic consists of a singl 44 The primary kinematic consists of a single particle which hits the
45 block perpendicular to the input face. Th 45 block perpendicular to the input face. The type of the particle
46 and its energy are set in the PrimaryGene 46 and its energy are set in the PrimaryGeneratorAction class, and can
47 changed via the G4 build-in commands of G 47 changed via the G4 build-in commands of G4ParticleGun class (see
48 the macros provided with this example). 48 the macros provided with this example).
49 The default is a Gamma of 100 TeV. 49 The default is a Gamma of 100 TeV.
50 50
51 In addition one can choose randomly the i 51 In addition one can choose randomly the impact point of the incident
52 particle. The corresponding interactive c 52 particle. The corresponding interactive command is built in
53 PrimaryGeneratorMessenger class. 53 PrimaryGeneratorMessenger class.
54 54
55 A RUN is a set of events. 55 A RUN is a set of events.
56 56
57 4- VISUALIZATION 57 4- VISUALIZATION
58 58
59 The Visualization Manager is set in the m 59 The Visualization Manager is set in the main() (see TestEm6.cc).
60 The initialisation of the drawing is done 60 The initialisation of the drawing is done via the command
61 > /control/execute vis.mac 61 > /control/execute vis.mac
62 62
63 The detector has a default view which is 63 The detector has a default view which is a longitudinal view of the box.
64 64
65 The tracks are drawn at the end of event, 65 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 66 Optionally one can choose to draw all particles, only the charged ones,
67 or none. This command is defined in Event 67 or none. This command is defined in EventActionMessenger class.
68 68
69 5- PHYSICS DEMO 69 5- PHYSICS DEMO
70 70
71 The particle's type and the physics proce 71 The particle's type and the physics processes which will be available
72 in this example are set in PhysicsList cl 72 in this example are set in PhysicsList class.
73 73
74 In addition a build-in interactive comman 74 In addition a build-in interactive command (/process/inactivate procname)
75 allows to activate/inactivate the process 75 allows to activate/inactivate the processes one by one.
76 76
77 The threshold for producing secondaries c 77 The threshold for producing secondaries can be changed.
78 eg: /run/particle/setCut 100 micrometer 78 eg: /run/particle/setCut 100 micrometer
79 /run/initialize 79 /run/initialize
80 << 80
81 To visualize the GammaConversionToMuons : 81 To visualize the GammaConversionToMuons :
82 /control/execute run01.mac 82 /control/execute run01.mac
83 /control/execute vis.mac 83 /control/execute vis.mac
84 /run/beamOn 84 /run/beamOn
85 << 85
86 To visualize the AnnihiToMuPair : 86 To visualize the AnnihiToMuPair :
87 /control/execute run11.mac 87 /control/execute run11.mac
88 /control/execute vis.mac 88 /control/execute vis.mac
89 /run/beamOn 89 /run/beamOn
90 << 90
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 ? 91 6- HOW TO START ?
96 92
97 - execute Test in 'batch' mode from macr 93 - execute Test in 'batch' mode from macro files
98 % TestEm6 run01.mac 94 % TestEm6 run01.mac
99 95
100 - execute Test in 'interactive mode' wit 96 - execute Test in 'interactive mode' with visualization
101 % TestEm6 97 % TestEm6
102 .... 98 ....
103 Idle> type your commands 99 Idle> type your commands
104 .... 100 ....
105 Idle> exit 101 Idle> exit
106 102
107 7- HOW TO INCREASE STATISTICS ON gamma -> mu+ 103 7- HOW TO INCREASE STATISTICS ON gamma -> mu+mu- ?
108 104
109 The processes of gamma -> mu+mu- and e+e 105 The processes of gamma -> mu+mu- and e+e- -> mu+mu-
110 have a low cross section but can be impor 106 have a low cross section but can be important
111 for leakage through thick absorbers and c 107 for leakage through thick absorbers and calorimeters.
112 Straight forward simulation will be quite 108 Straight forward simulation will be quite time consuming.
113 To make the processes more visible, the c 109 To make the processes more visible, the cross section can be
114 artificially increased by some factor (he 110 artificially increased by some factor (here 1000)
115 using the commands (only effective after 111 using the commands (only effective after /run/initialize)
116 112
117 /testem/phys/SetGammaToMuPairFac 1000 113 /testem/phys/SetGammaToMuPairFac 1000
118 /testem/phys/SetAnnihiToMuPairFac 1000 114 /testem/phys/SetAnnihiToMuPairFac 1000
119 115
120 116
121 8- HISTOGRAMS 117 8- HISTOGRAMS
122 118
123 Testem6 produces 6 histograms, h1 - h6, whic << 119 Testem6 produces 6 histograms which illustrate the final state of
124 the final state of the GammaConversionToMuon << 120 the GammaConversionToMuons process. See their definitions in RunAction.cc
125 with run02.mac and can be displayed with the <<
126 <<
127 The remaining histograms h7 - h16 show vario <<
128 of eeToHadr/eeToMu, see their definitions in <<
129 121
130 By default the histograms are saved as teste 122 By default the histograms are saved as testem6.root
131 123
132 The format of the histogram file can be : ro 124 The format of the histogram file can be : root (default), xml, csv,
133 by selecting the analysis manager default fi << 125 by selecting g4nnn.hh in RunAction.hh