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0001 -------------------------------------------------------------------
0002
0003 =========================================================
0004 Geant4 - an Object-Oriented Toolkit for Simulation in HEP
0005 =========================================================
0006
0007 fanoCavity2
0008 -----------
0009
0010 This program computes the dose deposited in an ionization chamber by an
0011 extended (one dimensional) monoenergetic electron source.
0012 The geometry of the chamber satisfies the conditions of charged particle
0013 equilibrium. Hence, under idealized conditions, the ratio of the dose
0014 deposited over the beam energy fluence must be equal to 1.
0015 This variante of the Fano cavity test make use of an reciprocity theorem.
0016
0017 J.Sempau and P.Andreo, Phys. Med. Biol. 51 (2006) 3533
0018
0019 1- GEOMETRY
0020
0021 The chamber is modelized as a cylinder with a cavity in it.
0022
0023 5 parameters define the geometry :
0024 - the radius of the chamber (must be big)
0025 - the material of the wall
0026 - the thickness of the wall
0027 - the material of the cavity
0028 - the thickness of the cavity
0029
0030 Wall and cavity must be made of the same material, but with different
0031 density.
0032 Radius must be bigger than range of electrons in cavity.
0033
0034 All above parameters can be redifined via the UI commands built in
0035 DetectorMessenger class.
0036
0037 _________________
0038 radius (infinite) | | | |
0039 | | | |
0040 | | | |
0041 | | | |
0042 | | <-+-----+--- cavity
0043 | | | |
0044 | | | |
0045 ---------------------------- cylinder axis = e- source
0046 | | | |
0047 | | | |
0048 | | | |
0049 |wall | |wall |
0050 | | | |
0051 | | | |
0052 | | | |
0053 -----------------
0054
0055 2- BEAM
0056
0057 Monoenergetic (E0) incident electron source is uniformly distribued along
0058 cylinder axis, within wall and cavity, with constant lineic density
0059 per mass: I.
0060 An effective wall thickness is defined from the range of e- at energy E0.
0061
0062 Beam_energy_fluence is E0*I
0063
0064 3- PURPOSE OF THE PROGRAM
0065
0066 The program computes the dose deposited in the cavity and the ratio
0067 Dose/Beam_energy_fluence. This ratio must be 1.
0068
0069 The program needs high statistic to reach precision on the computed dose.
0070 The UI command /run/printProgress allows to survey the convergence of
0071 the dose calculation.
0072
0073 The simplest way to study the effect of e- tracking parameters on dose
0074 deposition is to use the command /testem/stepMax.
0075
0076 4- PHYSICS
0077
0078 The physics list contains the standard electromagnetic processes, with few
0079 modifications listed here.
0080
0081 - Bremsstrahlung : Fano conditions imply no energy transfer via
0082 bremsstrahlung radiation. Therefore this process is not registered in the
0083 physics list. However, it is always possible to include it.
0084 See PhysListEm classes.
0085
0086 - Ionization : In order to have same stopping power in wall and cavity, one
0087 must cancel the density correction term in the dedx formula. This is done in
0088 a specific MollerBhabha model (MyMollerBhabhaModel) which inherites from
0089 G4MollerBhabhaModel.
0090
0091 To prevent explicit generation of delta-rays, the default production
0092 threshold (i.e. cut) is set to 10 km (CSDA condition).
0093
0094 The finalRange of the step function is set to 10 um, which more on less
0095 correspond to a tracking cut in water of about 20 keV. See emOptions.
0096 Once again, the above parameters can be controled via UI commands.
0097
0098 - Multiple scattering : is switched in single Coulomb scattering mode near
0099 boundaries. This is selected via EM options in PhysicsList, and can be
0100 controled with UI commands.
0101
0102 - All PhysicsTables are built with 100 bins per decade.
0103
0104 5- HISTOGRAMS
0105
0106 fanoCavity2 has several predefined 1D histograms :
0107
0108 1 : emission point of e+-
0109 2 : energy spectrum of e+-
0110 3 : theta distribution of e+-
0111 4 : emission point of e+- hitting cavity
0112 5 : energy spectrum of e+- when entering in cavity
0113 6 : theta distribution of e+- before enter in cavity
0114 7 : theta distribution of e+- at first step in cavity
0115 8 : track segment of e+- in cavity
0116 9 : step size of e+- in wall
0117 10 : step size of e+- in cavity
0118 11 : energy deposit in cavity per track
0119
0120 The histograms are managed by G4AnalysisManager class and its Messenger.
0121 The histos can be individually activated with the command :
0122 /analysis/h1/set id nbBins valMin valMax unit
0123 where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
0124
0125 One can control the name of the histograms file with the command:
0126 /analysis/setFileName name (default fanocavity2)
0127
0128 It is possible to choose the format of the histogram file : root (default),
0129 hdf5, xml, csv, by changing the default file type in HistoManager.cc
0130
0131 It is also possible to print selected histograms on an ascii file:
0132 /analysis/h1/setAscii id
0133 All selected histos will be written on a file name.ascii
0134 (default fanocavity2)
0135
0136 6- HOW TO START ?
0137
0138 - execute fanoCavity2 in 'batch' mode from macro files
0139 % fanoCavity2 run01.mac
0140
0141 - execute fanoCavity2 in 'interactive mode' with visualization
0142 % fanoCavity2
0143 ....
0144 Idle> type your commands
0145 ....
0146 Idle> exit
0147
0148 Alternative macro files:
0149 basic.mac - disabled multiple scattering and fluctuations of energy loss
0150 essai.mac - run WVI EM physics configuration
0151 stepfunction.mac - the step function optimisation using histogram
