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0001
0002 =========================================================
0003 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0004 =========================================================
0005
0006 Hadr03
0007 ------
0008
0009 How to compute total cross section from the direct evaluation of the
0010 mean free path ( see below, item Physics).
0011 How to identify nuclear reactions.
0012 How to plot energy spectrum of secondary particles.
0013
0014 1- GEOMETRY DEFINITION
0015
0016 It is a single box representing a 'semi infinite' homogeneous medium.
0017 Two parameters define the geometry :
0018 - the material of the box,
0019 - the (full) size of the box.
0020
0021 The default geometry (10 m of molybdenum) is built in DetectorConstruction,
0022 but the above parameters can be changed interactively via commands defined
0023 in DetectorMessenger.
0024
0025 2- PHYSICS LIST
0026
0027 The PhysicsList contains builders for hadronic interactions.
0028 Predefined G4 PhysicsConstructors or 'local' PhysicsConstructors can be used
0029 (see geant4/source/physics_lists or example runAndEvent/RE04).
0030
0031 In order not to introduce 'artificial' constraints on the step size,
0032 electromagnetic processes are not registered: there is no continuous energy
0033 loss.
0034
0035 Several hadronic physics options are controlled by environment variables.
0036 To select them, see Hadr03.cc.
0037
0038 3- AN EVENT : THE PRIMARY GENERATOR
0039
0040 The primary kinematic consists of a single particle starting at the edge
0041 of the box. The type of the particle and its energy are set in
0042 PrimaryGeneratorAction (neutron 1 MeV), and can be changed via the G4
0043 build-in commands of ParticleGun class (see the macros provided with
0044 this example).
0045
0046 4- PHYSICS
0047
0048 An event is killed at the first interaction of the incident particle.
0049 The absorption length, also called mean free path, is computed as
0050 the mean value of the track length of the incident particle.
0051 This is why the medium must be 'infinite' : to be sure that interaction
0052 occurs at any events.
0053
0054 The result is compared with the 'input' value, i.e. with the cross sections
0055 given by G4HadronicProcessStore and used by Geant4.
0056
0057 The list of nuclear reactions that occured is printed.
0058 (the number of gamma of deexcitation is not printed).
0059
0060 Then, comes the total list of generated particles and ions.
0061 The energy spectrum of the scattered particle (if any) and of the created
0062 secondaries are plotted (see SteppingAction).
0063
0064 Momentum conservation is checked as :
0065 momentum balance = modulus(P_out - P_in)
0066
0067 A set of macros defining various run conditions are provided.
0068 The processes can be actived/inactived in order to survey the processes
0069 individually.
0070
0071 5- HISTOGRAMS
0072
0073 The test contains 12 built-in 1D histograms, which are managed by
0074 G4AnalysisManager and its Messenger. The histos can be individually
0075 activated with the command :
0076 /analysis/h1/set id nbBins valMin valMax unit
0077 where unit is the desired unit for the histo (MeV or keV, etc..)
0078 (see the macros xxxx.mac).
0079
0080 1 "kinetic energy of scattered primary particle"
0081 2 "kinetic energy of gamma"
0082 3 "kinetic energy of e-"
0083 4 "kinetic energy of neutrons"
0084 5 "kinetic energy of protons"
0085 6 "kinetic energy of deuterons"
0086 7 "kinetic energy of alphas"
0087 8 "kinetic energy of nuclei"
0088 9 "kinetic energy of mesons"
0089 10 "kinetic energy of baryons"
0090 11 "Q = Ekin out - Ekin in"
0091 12 "Pbalance = mag(P_out - P_in)"
0092 13 "atomic mass of nuclei"
0093
0094 The histograms are managed by the HistoManager class and its Messenger.
0095 The histos can be individually activated with the command :
0096 /analysis/h1/set id nbBins valMin valMax unit
0097 where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
0098
0099 One can control the name of the histograms file with the command:
0100 /analysis/setFileName name (default Hadr03)
0101
0102 It is possible to choose the format of the histogram file : root (default),
0103 xml, csv, by using namespace in HistoManager.hh
0104
0105 It is also possible to print selected histograms on an ascii file:
0106 /analysis/h1/setAscii id
0107 All selected histos will be written on a file name.ascii (default Hadr03)
0108
0109 6- VISUALIZATION
0110
0111 The Visualization Manager is set in the main().
0112 The initialisation of the drawing is done via the commands
0113 /vis/... in the macro vis.mac. To get visualisation:
0114 > /control/execute vis.mac
0115
0116 The detector has a default view which is a longitudinal view of the box.
0117 The tracks are drawn at the end of event, and erased at the end of run.
0118
0119 7- HOW TO START ?
0120
0121 Execute Hadr03 in 'batch' mode from macro files :
0122 % Hadr03 inelastic.mac
0123
0124 Execute Hadr03 in 'interactive mode' with visualization :
0125 % Hadr03
0126 Idle> control/execute vis.mac
0127 ....
0128 Idle> type your commands
0129 ....
0130 Idle> exit
0131
0132 Macros provided in this example:
0133 - hadr03.in: macro used in Geant4 testing
0134 - Au196.mac: neutron (1 MeV) on Au195
0135 - elastic.mac: proton (10 MeV) on Mo100. Elastic collisions alone
0136 - fusion.mac: deuteron (400 keV) on tritium
0137 - gamma.mac: gamma (10 MeV) on Au196
0138 - inelastic.mac: proton (10 MaV) on Mo98. Inelastic interactions alone
0139 - ion.mac: Li7 (140 MeV) on Be9
0140 - nCapture.mac: neutron (1 eV) on Boron. Capture process alone
0141 - nFission.mac: neutron (1 eV) on U235. Fission process alone
0142 - neutron.mac: neutron (1 MeV) on Boron
0143
0144 Macros to be run interactively:
0145 - debug.mac: proton (10 MeV) on Boron
0146 - vis.mac: To activate visualization
