| Geant4 Cross Reference |
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4 Geant4 - an Object-Oriented Toolkit for S
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6
7 Example B3
8 ----------
9
10 This example simulates schematically a Positr
11
12 1- GEOMETRY DEFINITION
13
14 The support of gamma detection are scintill
15 of such crystals are optically grouped in a
16 this example, individual crystals are not d
17 crystals is and it is still called 'Crystal
18
19 Crystals are circularly arranged to form a
20 detector (gamma camera). This is done by po
21 Ring with an appropriate rotation matrix. S
22 then placed in the full detector.
23
24 The head of a patient is schematised as a h
25 tissue, placed at the center of full detect
26
27 The Crystal material, Lu2SiO5, is not inclu
28 Therefore, it is explicitly built in Define
29
30 2- PHYSICS LIST
31
32 The physics list contains standard electrom
33 radioactiveDecay module for GenericIon. It
34 class as a Geant4 modular physics list with
35 provided in Geant4:
36 - G4DecayPhysics - defines all particles an
37 - G4RadioactiveDecayPhysics - defines radio
38 - G4EmStandardPhysics - defines all EM stan
39
40 This physics list requires data files for:
41 - low energy electromagnetic processes whic
42 the G4LEDATA envirnoment variable
43 - nuclides properties which path is defined
44 the G4ENSDFSTATEDATA envirnoment variable
45 - radioactive decay hadronic processes whic
46 the G4RADIOACTIVEDATA envirnoment variabl
47
48 See more on installation of the datasets in
49 Chapter 3.3: Note On Geant4 Datasets:
50 http://geant4.web.cern.ch/geant4/UserDocume
51 /Ins
52 3- ACTION INITALIZATION
53
54 B3[a,b]::ActionInitialization class instant
55 all user action classes.
56
57 While in sequential mode the action classes
58 via invoking the method:
59 B3[a,b]::ActionInitialization::Build()
60 in multi-threading mode the same method is
61 and so all user action classes are defined
62
63 A run action class is instantiated both thr
64 and global that's why its instance is creat
65 B3[a,b]::ActionInitialization::BuildForM
66 which is invoked only in multi-threading mo
67
68 4- PRIMARY GENERATOR
69
70 The default particle beam is an ion (F18),
71 within a zone inside a patient and is defin
72 B3::PrimaryGeneratorAction::GeneratePrimari
73 The type of a primary particle can be chang
74 (see run2.mac).
75
76 5- DETECTOR RESPONSE: scorers
77
78 A 'good' event is an event in which an iden
79 deposited in two separate Crystals. A count
80 corresponds to a measure of the efficiency
81 The total dose deposited in a patient durin
82
83 Scorers are defined in B3::DetectorConstruc
84 two G4MultiFunctionalDetector objects: one
85 and one for the Patient (DoseDeposit)
86
87 The scorers hits are saved in form of ntupl
88 analysis tools. This feature is activated i
89 G4TScoreNtupleWriter.
90
91 Two variants of accumulation event statisti
92 in this example:
93
94 B3a:
95
96 At the end of event, the values acummulated
97 in B3a::RunAction and summed over the whole
98 In multi-threading mode the data accumulate
99 workers is merged to the master in B3a::Run
100 result is printed on the screen.
101
102 G4Accumulable<> type instead of G4double an
103 data members in order to facilitate merging
104 to the master. Currently the accumulables
105 and G4AccumulablesManager::Merge() has to b
106 to be further simplified with a closer inte
107 the Geant4 kernel next year.
108
109 B3b:
110
111 B3b::Run::RecordEvent(), called at end of e
112 event per event from the hits collections,
113 B3b::RunAction::EndOfRunAction().
114 In addition, results for dose are accumulat
115 standard floating-point summation and using
116 class called G4StatAnalysis. The G4StatAnal
117 (1) the sum, (2) sum^2, (3) number of entri
118 less than mean * machine-epsilon (the machi
119 between 1.0 and the next value representabl
120 From these 4 values, G4StatAnalysis provide
121 standard deviation, variance, coefficient o
122 and r2eff.
123
124 In multi-threading mode the statistics accu
125 to the master in B3b::Run::Merge().
126
127 6- STACKING ACTION
128
129 Beta decay of Fluor generates a neutrino. O
130 neutrino; therefore one kills it immediatel
131 are put in a stack.
132 The function B3::StackingAction::ClassifyNe
133 each time a new particle is created.
134
135 The following paragraphs are common to all ba
136
137 A- VISUALISATION
138
139 The visualization manager is set via the G4
140 in the main() function in exampleB3.cc.
141 The initialisation of the drawing is done v
142 in the macro vis.mac. This macro is automat
143 the main function when the example is used
144
145 By default, vis.mac opens an OpenGL viewer
146 The user can change the initial viewer by c
147 and instead uncommenting one of the other /
148 HepRepFile or DAWNFILE (which produce files
149 HepRApp and DAWN viewers, respectively). N
150 open new viewers at any time from the comma
151 you already have a view in, say, an OpenGL
152 "viewer-0", then
153 /vis/open DAWNFILE
154 then to get the same view
155 /vis/viewer/copyView viewer-0
156 or to get the same view *plus* scene-modifi
157 /vis/viewer/set/all viewer-0
158 then to see the result
159 /vis/viewer/flush
160
161 The DAWNFILE, HepRepFile drivers are always
162 (since they require no external libraries),
163 that the Geant4 libraries have been built w
164
165 Since 11.1, the TSG visualization driver ca
166 file output in png, jpeg, gl2ps formats wit
167 It can be controlled via UI commands provid
168 demonstrated in the tsg_offscreen.mac macro
169
170 For more information on visualization, incl
171 install and run DAWN, OpenGL and HepRApp, s
172 for example,
173 http://geant4.slac.stanford.edu/Presentatio
174 (where [VIS] can be replaced by DAWN, OpenG
175
176 The tracks are automatically drawn at the e
177 for all events and erased at the beginning
178
179 B- USER INTERFACES
180
181 The user command interface is set via the G
182 in the main() function in exampleB3.cc
183
184 The selection of the user command interface
185 according to the Geant4 configuration or it
186 the third argument of the G4UIExecutive con
187
188 The gui.mac macros are provided in examples
189 is automatically executed if Geant4 is buil
190 It is also possible to customise the icons
191 demonstrated in the icons.mac macro in exam
192
193 C- HOW TO RUN
194
195 - Execute exampleB3a in the 'interactive m
196 % ./exampleB3a
197 and type in the commands from run1.mac l
198 Idle> /control/verbose 2
199 Idle> /tracking/verbose 2
200 Idle> /run/beamOn 1
201 Idle> ...
202 Idle> exit
203 or
204 Idle> /control/execute run1.mac
205 ....
206 Idle> exit
207
208 - Execute exampleB3a in the 'batch' mode f
209 (without visualization)
210 % ./exampleB3a run2.mac
211 % ./exampleB3a exampleB3.in > exampleB
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