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0001
0002 =========================================================
0003 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0004 =========================================================
0005
0006 NeutronSource
0007 -------------
0008
0009 NeutronSource is an example of neutrons production. It illustrates the cooperative work
0010 of nuclear reactions and radioactive decay processes.
0011 It survey energy deposition and particle's flux.
0012 It uses PhysicsConstructor objects.
0013
0014
0015 1- MATERIALS AND GEOMETRY DEFINITION
0016
0017 The geometry is a cylinder (absorber) of an homogenous material (default : Beryllium oxide).
0018 This absorber is within a container (default : stainless-steel).
0019
0020 Five parameters define the geometry :
0021 - the material of the absorber
0022 - the radius and length of the absorber
0023 - the material of the container
0024 - the thickness of the container
0025
0026 The default geometry is built in DetectorConstruction, but the above
0027 parameters can be changed interactively via commands defined in DetectorMessenger.
0028
0029 The container is surrounded by a World volume (air)
0030
0031 A function, and its associated UI command, allows to build a material
0032 directly from a single isotope.
0033
0034 To be identified by the ThermalScattering module, the elements composing a
0035 material must have a specific name (see G4ParticleHPThermalScatteringNames.cc)
0036 Examples of such materials are build in DetectorConstruction of Hadr04,06,07.
0037
0038 2- PHYSICS LIST
0039
0040 "Full" set of physics processes are registered, but via PhysicsConstructor
0041 objects rather than complete pre-defined G4 physics lists. This alternative
0042 way may give more freedom to register physics.
0043
0044 Physics constructors are either constructors provided in Geant4 (with G4 prefix)
0045 or 'local'. They include : HadronElastic, HadronInelastic, IonsInelastic, GammaNuclear,
0046 RadioactiveDecay and Electomagnetic.
0047 (see geant4/source/physics_lists/constructors)
0048
0049 HadronElasticPhysicsHP include a model for thermalized neutrons, under the control of a command
0050 defined in NeutronHPMesseger.
0051
0052 GammmaNuclearPhysics is a subset of G4BertiniElectroNuclearBuilder.
0053
0054 ElectromagneticPhysics is a simplified version of G4EmStandardPhysics.
0055
0056 In PhysicsList::ConstructProcess() we give an example of how to access hadronic models.
0057
0058 Several hadronic physics options are controlled by environment variables.
0059 To select them, see NeutronSource.cc
0060
0061 3- AN EVENT : THE PRIMARY GENERATOR
0062
0063 The primary kinematic is a single particle uniformly shooted within the absorber.
0064 The type of the particle and its energy are set in PrimaryGeneratorAction (Am241, at rest),
0065 and can be changed via the G4 build-in commands of ParticleGun class
0066 (see the macros provided with this example).
0067
0068 4- PHYSICS
0069
0070 The program computes and plots energy deposited in the interaction volume
0071 (absorber + container) and the flux of particles leaving this volume.
0072 Processes invoked and particles generated during hadronic cascade are listed.
0073
0074 5- HISTOGRAMS
0075
0076 The test contains 13 built-in 1D histograms, which are managed by
0077 G4AnalysisManager and its Messenger. The histos can be individually
0078 activated with the command :
0079 /analysis/h1/set id nbBins valMin valMax unit
0080 where unit is the desired unit for the histo (MeV or keV, etc..)
0081 (see the macros xxxx.mac).
0082
0083 1 "total energy deposit"
0084 2 "dummy"
0085 3 "total kinetic energy flow"
0086 4 "energy spectrum of emerging gamma"
0087 5 "energy spectrum of emerging e+-"
0088 6 "energy spectrum of emerging neutrons"
0089 7 "energy spectrum of emerging protons"
0090 8 "energy spectrum of emerging deuterons"
0091 9 "energy spectrum of emerging alphas"
0092 10 "energy spectrum of all others emerging ions"
0093 11 "energy spectrum of all others emerging baryons"
0094 12 "energy spectrum of all others emerging mesons"
0095 13 "energy spectrum of all others emerging leptons (neutrinos)"
0096
0097 The histograms are managed by the HistoManager class and its Messenger.
0098 The histos can be individually activated with the command :
0099 /analysis/h1/set id nbBins valMin valMax unit
0100 where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
0101
0102 One can control the name of the histograms file with the command:
0103 /analysis/setFileName name (default NeutronSource)
0104
0105 It is possible to choose the format of the histogram file : root (default),
0106 xml, csv, by using namespace in HistoManager.hh
0107
0108 It is also possible to print selected histograms on an ascii file:
0109 /analysis/h1/setAscii id
0110 All selected histos will be written on a file name.ascii (default NeutronSource)
0111
0112 6- VISUALIZATION
0113
0114 The Visualization Manager is set in the main().
0115 The initialisation of the drawing is done via the commands
0116 /vis/... in the macro vis.mac. To get visualisation:
0117 > /control/execute vis.mac
0118
0119 The tracks are drawn at the end of event, and erased at the end of run.
0120 gamma green
0121 neutron yellow
0122 negative particles (e-, ...) red
0123 positive particles (e+, ions, ...) blue
0124
0125 7- HOW TO START ?
0126
0127 Execute NeutronSource in 'batch' mode from macro files :
0128 % NeutronSource run1.mac
0129 % NeutronSource neutronSource.in > neutronSource.out
0130
0131 Execute NeutronSource in 'interactive mode' with visualization :
0132 % NeutronSource
0133 Idle> control/execute vis.mac
0134 ....
0135 Idle> type your commands
0136 ....
0137 Idle> exit
0138
0139 Macros provided in this example:
0140 - run1.mac: Am-Be system (default configuration)
0141
0142 Macros to be run interactively:
0143 - debug.mac: Am-Be
0144 - vis.mac: To activate visualization
