| Geant4 Cross Reference |
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4 Geant4 - an Object-Oriented Toolkit for S
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6
7 Example B2
8 ----------
9
10 This example simulates a simplified fixed tar
11
12 1- GEOMETRY DEFINITION
13
14 The setup consists of a target followed b
15 transverse size at defined instances from
16 located in a region called the Tracker re
17 Their shape are cylinders, constructed as
18 (in B2a::DetectorConstruction) and as par
19 (in B2b::DetectorConstruction), see also
20
21 In addition, a global, uniform, and trans
22 applied using G4GlobalMagFieldMessenger,
23 B2[a,b]::DetectorConstruction::ConstructS
24 or via interactive commands.
25 For example:
26
27 /globalField/setValue 0.2 0 0 tesla
28
29 An instance of the B2::TrackerSD class is
30 logical chamber volume (in B2a) and with
31 with G4PVParameterised (in B2b).
32
33 One can change the materials of the targe
34 interactively via the commands defined in
35 (or B2b::DetectorMessenger). For example:
36
37 /B2/det/setTargetMaterial G4_WATER
38 /B2/det/setChamberMaterial G4_Ar
39
40 2- PHYSICS LIST
41
42 The particle's type and the physic proces
43 in this example are set in the FTFP_BERT
44 requires data files for electromagnetic a
45 See more on installation of the datasets
46 Chapter 3.3: Note On Geant4 Datasets:
47 http://geant4.web.cern.ch/geant4/UserDocu
48 The following datasets: G4LEDATA, G4LEVEL
49 G4ENSDFSTATEDATA are mandatory for this e
50
51 In addition, the build-in interactive com
52 /process/(in)activate processName
53 allows the user to activate/inactivate th
54
55 3- ACTION INITALIZATION
56
57 A newly introduced class, B2::ActionInitial
58 instantiates and registers to Geant4 kernel
59
60 While in sequential mode the action classes
61 via invoking the method:
62 B2::ActionInitialization::Build()
63 in multi-threading mode the same method is
64 and so all user action classes are defined
65
66 A run action class is instantiated both thr
67 and global that's why its instance has is c
68 B2::ActionInitialization::BuildForMaster
69 which is invoked only in multi-threading mo
70
71 4- PRIMARY GENERATOR
72
73 The primary generator action class employ
74 The primary kinematics consists of a sing
75 to the world boundary and hits the target
76 face. The type of the particle and its en
77 Geant4 built-in commands of the G4Particl
78
79 5- RUNS and EVENTS
80
81 A run is a set of events.
82
83 The user has control:
84 - at Begin and End of each run (class
85 - at Begin and End of each event (clas
86 - at Begin and End of each track (clas
87 - at End of each step (class SteppingAction,
88
89 The event number is written to the log fi
90 of events in B2::EventAction::BeginOfEven
91 B2::EventAction::EndOfEventAction().
92 Moreover, for the first 100 events and ev
93 information about the number of stored tr
94 is printed as well as the number of hits
95
96 The run number is printed at B2::RunActio
97 G4RunManager is also informed how to SetR
98 initial random number seeds per run or pe
99
100 6- USER LIMITS
101
102 This example also illustrates how to intro
103 like maximum step length, minimum kinetic
104 class and associated G4StepLimiter and G4U
105 See B2a::DetectorConstruction (or B2b::Det
106
107 The maximum step limit in the tracker regi
108 command (see B2a::DetectorMessenger, B2b::
109 For example:
110
111 /B2/det/stepMax 1.0 mm
112
113 7- DETECTOR RESPONSE
114
115 A HIT is a step per step record of all th
116 simulate and analyse the detector respons
117
118 In this example the Tracker chambers are
119 Therefore, the chambers are declared 'sen
120 the B2a::DetectorConstruction (or B2b::De
121 They are associated with an instance of t
122
123 Then, a Hit is defined as a set of 4 info
124 the chambers, namely:
125 - the track identifier (an integer),
126 - the chamber number,
127 - the total energy deposit in this step, and
128 - the position of the energy deposit.
129
130 A given hit is an instance of the class B
131 during the tracking of a particle, step b
132 B2::TrackerSD::ProcessHits(). This hit is
133
134 The HitsCollection is printed at the end
135 B2::TrackerSD::EndOfEvent()), under the c
136 /hits/verbose 2
137
138 The following paragraphs are common to all ba
139
140 A- VISUALISATION
141
142 The visualization manager is set via the G4
143 in the main() function in exampleB2a.cc (or
144 The initialisation of the drawing is done v
145 in the macro vis.mac. This macro is automat
146 the main function when the example is used
147
148 By default, vis.mac opens an OpenGL viewer
149 The user can change the initial viewer by c
150 and instead uncommenting one of the other /
151 HepRepFile or DAWNFILE (which produce files
152 HepRApp and DAWN viewers, respectively). N
153 open new viewers at any time from the comma
154 you already have a view in, say, an OpenGL
155 "viewer-0", then
156 /vis/open DAWNFILE
157 then to get the same view
158 /vis/viewer/copyView viewer-0
159 or to get the same view *plus* scene-modifi
160 /vis/viewer/set/all viewer-0
161 then to see the result
162 /vis/viewer/flush
163
164 The DAWNFILE, HepRepFile drivers are always
165 (since they require no external libraries),
166 that the Geant4 libraries have been built w
167
168 Since 11.1, the TSG visualization driver ca
169 file output in png, jpeg, gl2ps formats wit
170 It can be controlled via UI commands provid
171 demonstrated in the tsg_offscreen.mac macro
172
173 For more information on visualization, incl
174 install and run DAWN, OpenGL and HepRApp, s
175 for example,
176 http://geant4.slac.stanford.edu/Presentatio
177 (where [VIS] can be replaced by DAWN, OpenG
178
179 The tracks are automatically drawn at the e
180 for all events and erased at the beginning
181
182 B- USER INTERFACES
183
184 The user command interface is set via the G
185 in the main() function in exampleB2a.cc
186
187 The selection of the user command interface
188 according to the Geant4 configuration or it
189 the third argument of the G4UIExecutive con
190
191 The gui.mac macros are provided in examples
192 is automatically executed if Geant4 is buil
193 It is also possible to customise the icons
194 demonstrated in the icons.mac macro in exam
195
196 C- HOW TO RUN
197
198 - Execute exampleB2a in the 'interactive m
199 % exampleB2a
200 and type in the commands from run1.mac l
201 Idle> /tracking/verbose 1
202 Idle> /run/beamOn 1
203 Idle> ...
204 Idle> exit
205 or
206 Idle> /control/execute run1.mac or ru
207 ....
208 Idle> exit
209
210 - Execute exampleB2a in the 'batch' mode f
211 (without visualization)
212 % exampleB2a run2.mac
213 % exampleB2a exampleB2.in > exampleB2.
214