| Geant4 Cross Reference |
>> 1 $Id: README 93739 2015-10-30 11:04:09Z gcosmo $
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.
12 13
13 1- GEOMETRY DEFINITION 14 1- GEOMETRY DEFINITION
14 15
15 The geometry consists of a single block o 16 The geometry consists of a single block of a homogenous material.
16 17
17 Two parameters define the geometry : 18 Two parameters define the geometry :
18 - the material of the box, 19 - the material of the box,
19 - the (full) size of the box. 20 - the (full) size of the box.
20 The default is 500 m of iron. 21 The default is 500 m of iron.
21 22
22 In addition a transverse uniform magnetic 23 In addition a transverse uniform magnetic field can be applied.
23 24
24 The default geometry is constructed in De 25 The default geometry is constructed in DetectorConstruction class,
25 but all of the above parameters can be ch 26 but all of the above parameters can be changed interactively via
26 the commands defined in the DetectorMesse 27 the commands defined in the DetectorMessenger class.
27 28
28 2- PHYSICS LIST 29 2- PHYSICS LIST
29 30
30 Physics Lists are based on modular design 31 Physics Lists are based on modular design. Several modules are
31 instantiated: 32 instantiated:
32 1. Transportation 33 1. Transportation
33 2. EM physics 34 2. EM physics
34 3. Decays 35 3. Decays
35 4. StepMax - for step limitation 36 4. StepMax - for step limitation
36 37
37 The electromagnetic physics is chosen fro 38 The electromagnetic physics is chosen from one of the Geant4 EM
38 physics constructors in the physics_list 39 physics constructors in the physics_list library.
39 40
40 Cross sections can be enhanced (see below 41 Cross sections can be enhanced (see below).
41 42
42 3- AN EVENT : THE PRIMARY GENERATOR 43 3- AN EVENT : THE PRIMARY GENERATOR
43 44
44 The primary kinematic consists of a singl 45 The primary kinematic consists of a single particle which hits the
45 block perpendicular to the input face. Th 46 block perpendicular to the input face. The type of the particle
46 and its energy are set in the PrimaryGene 47 and its energy are set in the PrimaryGeneratorAction class, and can
47 changed via the G4 build-in commands of G 48 changed via the G4 build-in commands of G4ParticleGun class (see
48 the macros provided with this example). 49 the macros provided with this example).
49 The default is a Gamma of 100 TeV. 50 The default is a Gamma of 100 TeV.
50 51
51 In addition one can choose randomly the i 52 In addition one can choose randomly the impact point of the incident
52 particle. The corresponding interactive c 53 particle. The corresponding interactive command is built in
53 PrimaryGeneratorMessenger class. 54 PrimaryGeneratorMessenger class.
54 55
55 A RUN is a set of events. 56 A RUN is a set of events.
56 57
57 4- VISUALIZATION 58 4- VISUALIZATION
58 59
59 The Visualization Manager is set in the m 60 The Visualization Manager is set in the main() (see TestEm6.cc).
60 The initialisation of the drawing is done 61 The initialisation of the drawing is done via the command
61 > /control/execute vis.mac 62 > /control/execute vis.mac
62 63
63 The detector has a default view which is 64 The detector has a default view which is a longitudinal view of the box.
64 65
65 The tracks are drawn at the end of event, 66 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 67 Optionally one can choose to draw all particles, only the charged ones,
67 or none. This command is defined in Event 68 or none. This command is defined in EventActionMessenger class.
68 69
69 5- PHYSICS DEMO 70 5- PHYSICS DEMO
70 71
71 The particle's type and the physics proce 72 The particle's type and the physics processes which will be available
72 in this example are set in PhysicsList cl 73 in this example are set in PhysicsList class.
73 74
74 In addition a build-in interactive comman 75 In addition a build-in interactive command (/process/inactivate procname)
75 allows to activate/inactivate the process 76 allows to activate/inactivate the processes one by one.
76 77
77 The threshold for producing secondaries c 78 The threshold for producing secondaries can be changed.
78 eg: /run/particle/setCut 100 micrometer 79 eg: /run/particle/setCut 100 micrometer
79 /run/initialize 80 /run/initialize
80 << 81
81 To visualize the GammaConversionToMuons : 82 To visualize the GammaConversionToMuons :
82 /control/execute run01.mac 83 /control/execute run01.mac
83 /control/execute vis.mac 84 /control/execute vis.mac
84 /run/beamOn 85 /run/beamOn
85 << 86
86 To visualize the AnnihiToMuPair : 87 To visualize the AnnihiToMuPair :
87 /control/execute run11.mac 88 /control/execute run11.mac
88 /control/execute vis.mac 89 /control/execute vis.mac
89 /run/beamOn 90 /run/beamOn
90 << 91
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 ? 92 6- HOW TO START ?
96 93
97 - execute Test in 'batch' mode from macr 94 - execute Test in 'batch' mode from macro files
98 % TestEm6 run01.mac 95 % TestEm6 run01.mac
99 96
100 - execute Test in 'interactive mode' wit 97 - execute Test in 'interactive mode' with visualization
101 % TestEm6 98 % TestEm6
102 .... 99 ....
103 Idle> type your commands 100 Idle> type your commands
104 .... 101 ....
105 Idle> exit 102 Idle> exit
106 103
107 7- HOW TO INCREASE STATISTICS ON gamma -> mu+ 104 7- HOW TO INCREASE STATISTICS ON gamma -> mu+mu- ?
108 105
109 The processes of gamma -> mu+mu- and e+e 106 The processes of gamma -> mu+mu- and e+e- -> mu+mu-
110 have a low cross section but can be impor 107 have a low cross section but can be important
111 for leakage through thick absorbers and c 108 for leakage through thick absorbers and calorimeters.
112 Straight forward simulation will be quite 109 Straight forward simulation will be quite time consuming.
113 To make the processes more visible, the c 110 To make the processes more visible, the cross section can be
114 artificially increased by some factor (he 111 artificially increased by some factor (here 1000)
115 using the commands (only effective after 112 using the commands (only effective after /run/initialize)
116 113
117 /testem/phys/SetGammaToMuPairFac 1000 114 /testem/phys/SetGammaToMuPairFac 1000
118 /testem/phys/SetAnnihiToMuPairFac 1000 115 /testem/phys/SetAnnihiToMuPairFac 1000
119 116
120 117
121 8- HISTOGRAMS 118 8- HISTOGRAMS
122 119
123 Testem6 produces 6 histograms, h1 - h6, whic << 120 Testem6 produces 6 histograms which illustrate the final state of
124 the final state of the GammaConversionToMuon << 121 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 <<
129 122
130 By default the histograms are saved as teste 123 By default the histograms are saved as testem6.root
131 124
132 The format of the histogram file can be : ro 125 The format of the histogram file can be : root (default), xml, csv,
133 by selecting the analysis manager default fi << 126 by selecting g4nnn.hh in RunAction.hh