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1$Id: README,v 1.1 2002/03/05 15:21:55 gcosmo Exp $
2-------------------------------------------------------------------
3
4 =========================================================
5 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
6 =========================================================
7
8 ParN02
9 ------
10
11
12 This example simulates a simplified fixe target experiment.
13 Read 000README for a description of how to run it in parallel.
14
15 1- GEOMETRY DEFINITION
16
17 The setup consists of a target followed by six chambers of increasing
18 transverse size. These chambers are located in a region called Tracker
19 region. Their shape are boxes, constructed as parametrised volumes
20 (ChamberParametrisation class).
21
22 The default geometry is constructed in DetectorConstruction class.
23 One can change the material of the target and of the chambers
24 interactively via the commands defined in the DetectorMessenger class.
25
26 In addition a transverse uniform magnetic field can be applied (see
27 N02MagneticField and DetectorMessenger classes).
28
29
30 2- PHYSICS LIST
31
32 The particle's type and the physic processes which will be available
33 in this example are set in PhysicsList class.
34
35 In this example, all the so called 'electromagnetic processes' are
36 introduced for gamma, charged leptons, and charged hadrons (see the
37 method PhysicsList::ConstructEM()).
38
39 An important data member of this class is the defaultCutValue which
40 defines the production threshold of secondary particles
41 (mainly Ionisation and Bremsstrahlung processes are concerned by this
42 CutValue).
43 Notice that the CutValue must be given in unit of length, corresponding
44 to the stopping range of the particle. It is automatically converted
45 in energy for each material, and a table is printed in the method
46 PhysicsList::SetCuts()
47
48 In addition the build-in interactive command:
49 /process/(in)activate processName
50 allows to activate/inactivate the processes one by one.
51
52
53 3- RUNS and EVENTS
54
55 The primary kinematic consists of a single particle which hits the
56 target perpendicular to the input face. The type of the particle
57 and its energy are set in the PrimaryGeneratorAction class, and can
58 be changed via the G4 build-in commands of ParticleGun class.
59
60 A RUN is a set of events.
61
62 The user has control:
63 -at Begin and End of each run (class RunAction)
64 -at Begin and End of each event (class EventAction)
65 -at Begin and End of each track (class TrackingAction, not used here)
66 -at End of each step (class SteppingAction)
67
68 The class SteppingVerbose prints some informations step per step,
69 under the control of the command: /tracking/verbose 1
70 It inherits from G4SteppingVerbose, and has been setup here in order
71 to illustrate how to extract informations from the G4 kernel during
72 the tracking of a particle.
73
74
75 4- DETECTOR RESPONSE
76
77 A HIT is a record, track per track (even step per step), of all the
78 informations needed to simulate and analyse the detector response.
79
80 In this example the Tracker chambers are considered as the detector.
81 Therefore the chambers are declared 'sensitive detectors' (SD) in
82 the DetectorConstruction class.
83
84 Then, a Hit is defined as a set of 4 informations per step, inside
85 the chambers, namely:
86 - the track identifier (an integer),
87 - the chamber number,
88 - the total energy deposit in this step,
89 - the position of the deposit.
90
91 A given hit is an instance of the class TrackerHit which is created
92 during the tracking of a particle, step by step, in the method
93 TrackerSD::ProcessHits(). This hit is inserted in a HitsCollection.
94
95 The HitsCollection is printed at the end of event (via the method
96 TrackerSD::EndOfEvent()), under the control of the command: /hits/verbose 1
97
98
99 5- VISUALIZATION
100
101 The Visualization Manager is set in the main().
102 The initialisation of the drawing is done via a set of /vis/ commands
103 in the macro vis.mac. This macro is automatically read from
104 the main when running in interactive mode.
105
106 The tracks are automatically drawn at the end of event and erased at
107 the beginning of the next run.
108
109 The visualization (with OpenGL driver) assumes two things:
110 1- the visualisation & interfaces categories have been compiled
111 with the environment variable G4VIS_BUILD_OPENGLX_DRIVER.
112 2- ParN02.cc has been compiled with G4VIS_USE_OPENGLX.
113
114 (The same with DAWNFILE instead of OPENGLX)
115
116
117 6- USER INTERFACES
118
119 The default command interface, called G4UIterminal, is done via
120 standart cin/G4cout.
121 On Linux and Sun-cc on can use a smarter command interface G4UItcsh.
122 It is enough to set the environment variable G4UI_USE_TCSH before
123 compiling ParN02.cc
124
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