| Geant4 Cross Reference |
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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 TestEm18 7 TestEm18
8 -------- 8 --------
9 This example allows to study the various c 9 This example allows to study the various contributions of the energy lost
10 by a charged particle in a single layer of 10 by a charged particle in a single layer of an homogeneous material.
11 See any textbook of interactions of charge 11 See any textbook of interactions of charged particles with matter, in particular :
12 1- geant4.web.cern.ch --> UserSupport -- 12 1- geant4.web.cern.ch --> UserSupport --> Physics Reference Manual
13 2- lappweb.in2p3.fr/~maire/tutorials/ind 13 2- lappweb.in2p3.fr/~maire/tutorials/index.html
14 14
15 1- GEOMETRY DEFINITION 15 1- GEOMETRY DEFINITION
16 16
17 It is a simple cubic box of homogeneous ma 17 It is a simple cubic box of homogeneous material.
18 Two parameters define the geometry : 18 Two parameters define the geometry :
19 - the material of the box, 19 - the material of the box,
20 - the thickness of the box. 20 - the thickness of the box.
21 21
22 The default geometry (1 cm of water) is co 22 The default geometry (1 cm of water) is constructed in DetectorConstruction,
23 but the above parameters can be changed in 23 but the above parameters can be changed interactively via the commands
24 defined in DetectorMessenger. 24 defined in DetectorMessenger.
25 25
26 2- PHYSICS 26 2- PHYSICS
27 27
28 The physics list contains the 'standard' e 28 The physics list contains the 'standard' electromagnetic processes.
29 However the MultipleScattering is not regi 29 However the MultipleScattering is not registered, in order to focuse on
30 fluctuations of to energy loss alone. 30 fluctuations of to energy loss alone.
31 31
32 3- BEAM 32 3- BEAM
33 33
34 The primary kinematic is a single particle 34 The primary kinematic is a single particle starting at the edge
35 of the box. The type of the particle and i 35 of the box. The type of the particle and its energy are set in
36 PrimaryGeneratorAction (e- 10 MeV), and ca 36 PrimaryGeneratorAction (e- 10 MeV), and can be changed via the G4
37 build-in commands of ParticleGun class. 37 build-in commands of ParticleGun class.
38 38
39 4- RUN 39 4- RUN
40 40
41 During the tracking of the incident partic 41 During the tracking of the incident particle, by default, the secondary
42 particles are immediately killed, after th 42 particles are immediately killed, after that their energy has been registered
43 (see SteppingAction and StackingAction). 43 (see SteppingAction and StackingAction).
44 Therefore, we study here the various compo 44 Therefore, we study here the various components of the total energy lost
45 by the incident particle, not the energy d 45 by the incident particle, not the energy deposited in a layer of finite
46 thickness. 46 thickness.
47 With the option /testEm/trackSecondaries o 47 With the option /testEm/trackSecondaries one can compute and plot the energy
48 deposited in the layer. See edep.mac 48 deposited in the layer. See edep.mac
49 49
50 At EndOfRun, the above results are compare 50 At EndOfRun, the above results are compared with 'reference' values,
51 i.e. the input data read from EnergyLoss a 51 i.e. the input data read from EnergyLoss and Range tables.
52 See reference 2 : Energy-Range relation, s 52 See reference 2 : Energy-Range relation, slide 4.
53 53
54 5- HISTOGRAMS 54 5- HISTOGRAMS
55 55
56 The test contains 13 built-in 1D histogram 56 The test contains 13 built-in 1D histograms, which are managed by
57 G4AnalysisManager and its Messenger. 57 G4AnalysisManager and its Messenger.
58 58
59 1 step size of primary track 59 1 step size of primary track
60 2 energy continuously deposited al 60 2 energy continuously deposited along primary track
61 3 energy transfered to secondaries 61 3 energy transfered to secondaries by ionisation
62 4 energy transfered to secondaries 62 4 energy transfered to secondaries by Bremsstrahlung
63 5 energy transfered to secondaries 63 5 energy transfered to secondaries by (e+,e-) production
64 6 total energy transfered to secon 64 6 total energy transfered to secondaries
65 7 total energy lost by primary tra 65 7 total energy lost by primary track
66 8 total energy lost by primary tra 66 8 total energy lost by primary track from energy balance
67 9 energy continuously deposited al 67 9 energy continuously deposited along secondary tracks
68 10 total energy deposited 68 10 total energy deposited
69 11 energy spectrum of gamma 69 11 energy spectrum of gamma
70 12 energy spectrum of e- 70 12 energy spectrum of e-
71 13 energy spectrum of e+ 71 13 energy spectrum of e+
72 72
73 The histograms are defined in HistoManager 73 The histograms are defined in HistoManager.
74 74
75 The histos can be activated individually w 75 The histos can be activated individually with the command :
76 /analysis/h1/set id nbBins valMin valMax u 76 /analysis/h1/set id nbBins valMin valMax unit
77 where 'unit' is the desired unit for the h 77 where 'unit' is the desired unit for the histo (MeV or KeV, cm or mm, etc..)
78 78
79 One can control the name of the histograms 79 One can control the name of the histograms file with the command:
80 /analysis/setFileName name (default test 80 /analysis/setFileName name (default testem18)
81 81
82 It is possible to choose the format of the 82 It is possible to choose the format of the histogram file : root (default),
83 xml, csv, by using namespace in HistoManag << 83 xml, csv, by using namespace in HistoManager.hh
84 For convenience, few simple Root macros ar << 84
85 It is also possible to print selected hist 85 It is also possible to print selected histograms on an ascii file:
86 /analysis/h1/setAscii id 86 /analysis/h1/setAscii id
87 All selected histos will be written on a f 87 All selected histos will be written on a file name.ascii (default testem18)
88 88
89 6- VISUALIZATION 89 6- VISUALIZATION
90 90
91 The Visualization Manager is set in the ma 91 The Visualization Manager is set in the main().
92 The initialisation of the drawing is done 92 The initialisation of the drawing is done via the commands
93 /vis/... in the macro vis.mac. To get visu 93 /vis/... in the macro vis.mac. To get visualisation:
94 > /control/execute vis.mac 94 > /control/execute vis.mac
95 95
96 The detector has a default view which is a 96 The detector has a default view which is a longitudinal view of the box.
97 The tracks are drawn at the end of event, 97 The tracks are drawn at the end of event, and erased at the end of run.
98 98
99 7- HOW TO START ? 99 7- HOW TO START ?
100 100
101 execute TestEm18 in 'batch' mode from macr 101 execute TestEm18 in 'batch' mode from macro files :
102 % TestEm18 electron.mac 102 % TestEm18 electron.mac
103 103
104 execute TestEm18 in 'interactive mode' wit 104 execute TestEm18 in 'interactive mode' with visualization :
105 % TestEm18 105 % TestEm18
106 Idle> control/execute vis.mac 106 Idle> control/execute vis.mac
107 .... 107 ....
108 Idle> type your commands 108 Idle> type your commands
109 .... 109 ....
110 Idle> exit 110 Idle> exit
111 <<
112 Macros provided in this example: <<
113 - csda.mac: test independance of user step m <<
114 - edep.mac: track secondary particles and pl <<
115 - electron.mac: e- (10 MeV) on 1 cm of water <<
116 - ion.mac: ion C12 (4 GeV) on 1 cm of water <<
117 - muon.mac: mu+ (1 TeV) on 1 m of water <<
118 - pixe.mac: proton (20 MeV) on 50 um of gold <<
119 - proton.mac: proton (1 GeV) on 10 cm of wat <<
120 - plotHisto.C, pixe.C: Root macros <<
121 <<
122 Macros to be run interactively: <<
123 - vis.mac: To activate visualization <<