source: trunk/examples/extended/eventgenerator/exgps/README

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1
2 =========================================================
3 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
4 =========================================================
5
6 Extended Example for G4GeneralParticleSource (GPS)
7 ---------------------------------------
8
9 exGPS is created to demonstrate the usage of G4GeneralParticleSource for generating
10 primary incident particle according to user defined distributions. These range from simple
11 monocromatic point source to complicated mutiple sources with various biasing schemes.
12
13 More detailed information on the usage of GPS are available on its home site:
14 http://reat.space.qinetiq.com/gps
15
16 -------------------------------------------------------------------------------------------
17 1. GEOMETRY
18
19 Simple geometry consists of a "Vacuum" world and, in it with two other components:
20
21 - An alunimium box : 20 x 20 x 20 cm in size, cerntered at the origin.
22
23 - A SiO2 sphere: 5 cm in radius and is placed in the centre of the aluminium box.
24
25 2. PHYSICS
26
27 Tranportation process only for all particles.
28
29 3. EVENT:
30
31 The event generator is the G4GeneralParticleSource (GPS). The instantiation of G4GeneralParticleSource
32 is same as that for G4ParticleGun. See the exGPSPrimaryGeneratorAction.cc file for details .
33
34 5. VISUALIZATION:
35
36 Visualisation of the geometry and the tracks is possible with many of the G4 visualisation packages. An
37 example of displaying the geometry and tracks using VRML is given in the macro file vis.mac.
38
39 6. ANALYSIS:
40
41 This example implements an AIDA-compliant analysis manager which creates histograms and ntuples.
42 If user has an AIDA-compliant tool such as AIDAJNI, ANAPHE, OpenScientist or PI installed on his/her system. Some URLs :
43 http://aida.freehep.org/
44 http://java.freehep.org/aidajni
45 http://www.cern.ch/PI
46 http://OpenScientist.lal.in2p3.fr
47
48 The analysis part of this example can be activated by doing a "source
49 aida-setup" of the AIDA compliant tool (to activate the aida-config
50 program) and by raising some environment variabless so that the
51 G4 GNUmakefile system can take into account the AIDA tool.
52 This can be done, for example on a UNIX under a csh like shell, with :
53 csh> source <path_where_the_AIDA_tool_is_installed>/aida-setup.csh
54 csh> aida-config # to check that this program is up and running
55 G4 related part :
56 csh> setenv G4ANALYSIS_USE 1
57 csh> setenv G4ANALYSIS_AIDA_CONFIG_CFLAGS `aida-config --include`
58 csh> setenv G4ANALYSIS_AIDA_CONFIG_LIBS `aida-config --lib`
59
60 (It may be usefull to note that in the G4 GNUmakefile system,
61 the upper variables are used in the file config/analysis.gmk).
62
63 This needs to be done before building the executable.
64
65 At the end of an excution, an xml file "exgps.aida" is created by default which contains
66 histograms and ntuples. User can change the name and format of this output file with the commands
67
68 /analysis/filetype new-type
69 /analysis/fileName new-filename
70
71 e.g.
72
73 /analysis/filetype root
74 /analysis/filename myfile.root
75
76 these change the output file format to ROOT and output file name to "myfile.root". There are three file
77 formats to choose from: xml, root or hbook.
78
79 The output file conatins 6 histograms and one ntuple:
80
81 histogram 1: The energy spectrum of the primary particles.
82 histogram 2: 2d histogram of primary particle incident position distribution in the X-Y plane.
83 histogram 3: 2d histogram of primary particle incident position distribution in the X-Z plane.
84 histogram 4: 2d histogram of primary particle incident position distribution in the Y-Z plane.
85 histogram 5: 2d histogram of primary particle incident angle distribution in terms of Phi/Cos(Theta).
86 histogram 6: 2d histogram of primary particle incident angle distribution in terms of Phi/Theta.
87
88 The binnings of the histograms can be changed with the UI commands avialable under the
89 /analysis directory.
90
91 In the ntuple the following data are recorded for each incident particle:
92
93 Particle ID
94 Incident Position (x,y,z);
95 Incident Angle (theta,phi);
96 Particle weight;
97
98 7. GETTING STARTED:
99
100 i) If you have an AIDA-compliant analysis package installed, then you should switch on the analysis
101 part of the example by:
102
103 setenv G4ANALYSIS_USE 1
104
105 otherwise do
106
107 unsetenv G4ANALYSIS_USE
108
109 to remove the generation of an output file.
110
111 ii) Build the exGPS executable:
112
113 cd to exgps
114 gmake clean
115 gmake
116
117 gmake will create tmp and bin directories in your $G4TMP and $G4BIN directories.
118 The executable, named exGPS, will be created in the $G4BIN/$G4SYSTEM/ directory.
119
120 iii) Run the executable:
121
122 while in the exgps directory do
123
124 $G4BIN/$G4SYSTEM/exGPS exrgps.in
125
126 If G4ANALYSIS_USE is defined, and dpends on the particular AIDA system used, e.g. JAIDA, one could see
127 a display window of the six histograms. It may be neccessary to close the plotter window in order to
128 terminate the execution. After the termination one will find the "exgps.aida", as well as a vrml file
129 "g4_00.wrl" in the directory.
130
131 8. FURTHER EXAMPLES of MACRO FILES:
132
133 There are a number of g4mac files in the ./macros subdirectory, to show the various features of GPS.
134 Most of them will lead to the creation of an aida file in the same name as the macro file.
135 These aida files can be examed and analysed with an analysis tool such as JAS3.
136
137 Please see the README file there for further information.
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