| 1 | $Id: README,v 1.11 2009/10/31 18:05:56 maire Exp $
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| 2 | -------------------------------------------------------------------
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| 3 |
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| 4 | =========================================================
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| 5 | Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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| 6 | =========================================================
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| 7 |
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| 8 | fanoCavity2
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| 9 | -----------
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| 10 |
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| 11 | This program computes the dose deposited in an ionization chamber by an
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| 12 | extended (one dimensional) monoenergetic electron source.
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| 13 | The geometry of the chamber satisfies the conditions of charged particle
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| 14 | equilibrium. Hence, under idealized conditions, the ratio of the dose
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| 15 | deposited over the beam energy fluence must be equal to 1.
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| 16 | This variante of the Fano cavity test make use of an reciprocity theorem.
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| 17 |
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| 18 | J.Sempau and P.Andreo, Phys. Med. Biol. 51 (2006) 3533
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| 19 |
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| 20 | 1- GEOMETRY
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| 21 |
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| 22 | The chamber is modelized as a cylinder with a cavity in it.
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| 23 |
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| 24 | 5 parameters define the geometry :
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| 25 | - the radius of the chamber (must be big)
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| 26 | - the material of the wall
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| 27 | - the thickness of the wall
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| 28 | - the material of the cavity
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| 29 | - the thickness of the cavity
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| 30 |
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| 31 | Wall and cavity must be made of the same material, but with different
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| 32 | density.
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| 33 | Radius must be bigger than range of electrons in cavity.
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| 34 |
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| 35 | All above parameters can be redifined via the UI commands built in
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| 36 | DetectorMessenger class.
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| 37 |
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| 38 | _________________
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| 39 | radius (infinite) | | | |
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| 40 | | | | |
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| 41 | | | | |
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| 42 | | | | |
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| 43 | | | <-+-----+--- cavity
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| 44 | | | | |
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| 45 | | | | |
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| 46 | ---------------------------- cylinder axis = e- source
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| 47 | | | | |
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| 48 | | | | |
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| 49 | | | | |
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| 50 | |wall | |wall |
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| 51 | | | | |
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| 52 | | | | |
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| 53 | | | | |
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| 54 | -----------------
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| 55 |
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| 56 | 2- BEAM
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| 57 |
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| 58 | Monoenergetic (E0) incident electron source is uniformly distribued along
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| 59 | cylinder axis, within wall and cavity, with constant lineic density
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| 60 | per mass: I.
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| 61 | An effective wall thickness is defined from the range of e- at energy E0.
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| 62 |
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| 63 | Beam_energy_fluence is E0*I
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| 64 |
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| 65 | 3- PURPOSE OF THE PROGRAM
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| 66 |
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| 67 | The program computes the dose deposited in the cavity and the ratio
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| 68 | Dose/Beam_energy_fluence. This ratio must be 1.
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| 69 |
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| 70 | The program needs high statistic to reach precision on the computed dose.
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| 71 | The UI command /testem/event/printModulo allows to survey the convergence of
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| 72 | the dose calculation.
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| 73 |
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| 74 | The simplest way to study the effect of e- tracking parameters on dose
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| 75 | deposition is to use the command /testem/stepMax.
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| 76 |
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| 77 | 4- PHYSICS
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| 78 |
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| 79 | The physics list contains the standard electromagnetic processes, with few
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| 80 | modifications listed here.
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| 81 |
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| 82 | - Bremsstrahlung : Fano conditions imply no energy transfer via
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| 83 | bremsstrahlung radiation. Therefore this process is not registered in the
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| 84 | physics list. However, it is always possible to include it.
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| 85 | See PhysListEm classes.
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| 86 |
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| 87 | - Ionization : In order to have same stopping power in wall and cavity, one
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| 88 | must cancel the density correction term in the dedx formula. This is done in
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| 89 | a specific MollerBhabha model (MyMollerBhabhaModel) which inherites from
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| 90 | G4MollerBhabhaModel.
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| 91 |
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| 92 | To prevent explicit generation of delta-rays, the default production
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| 93 | threshold (i.e. cut) is set to 10 km (CSDA condition).
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| 94 |
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| 95 | The finalRange of the step function is set to 10 um, which more on less
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| 96 | correspond to a tracking cut in water of about 20 keV. See emOptions.
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| 97 | Once again, the above parameters can be controled via UI commands.
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| 98 |
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| 99 | - Multiple scattering : is switched in single Coulomb scattering mode near
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| 100 | boundaries. This is selected via EM options in PhysicsList, and can be
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| 101 | controled with UI commands.
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| 102 |
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| 103 | - All PhysicsTables are built with 100 bins per decade.
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| 104 |
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| 105 | 5- HISTOGRAMS
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| 106 |
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| 107 | fanoCavity2 has several predefined 1D histograms :
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| 108 |
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| 109 | 1 : emission point of e+-
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| 110 | 2 : energy spectrum of e+-
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| 111 | 3 : theta distribution of e+-
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| 112 | 4 : emission point of e+- hitting cavity
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| 113 | 5 : energy spectrum of e+- when entering in cavity
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| 114 | 6 : theta distribution of e+- before enter in cavity
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| 115 | 7 : theta distribution of e+- at first step in cavity
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| 116 | 8 : track segment of e+- in cavity
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| 117 | 9 : step size of e+- in wall
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| 118 | 10 : step size of e+- in cavity
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| 119 | 11 : energy deposit in cavity per track
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| 120 |
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| 121 | The histograms are managed by the HistoManager class and its Messenger.
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| 122 | The histos can be individually activated with the command :
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| 123 | /testem/histo/setHisto id nbBins valMin valMax unit
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| 124 | where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
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| 125 |
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| 126 | One can control the name of the histograms file with the command:
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| 127 | /testem/histo/setFileName name (default fanocavity2)
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| 128 |
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| 129 | It is possible to choose the format of the histogram file (hbook, root, XML)
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| 130 | with the command /testem/histo/setFileType (root by default)
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| 131 |
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| 132 | It is also possible to print selected histograms on an ascii file:
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| 133 | /testem/histo/printHisto id
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| 134 | All selected histos will be written on a file name.ascii (default fanocavity2)
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| 135 |
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| 136 | Note that, by default, histograms are disabled. To activate them, uncomment
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| 137 | the flag G4ANALYSIS_USE in GNUmakefile.
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| 138 |
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| 139 | 6- HOW TO START ?
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| 140 |
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| 141 | - compile and link to generate an executable
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| 142 | % cd geant4/examples/extended/medical/fanoCavity2
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| 143 | % gmake
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| 144 |
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| 145 | - execute fanoCavity2 in 'batch' mode from macro files
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| 146 | % fanoCavity2 run01.mac
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| 147 |
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| 148 | - execute fanoCavity2 in 'interactive mode' with visualization
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| 149 | % fanoCavity2
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| 150 | ....
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| 151 | Idle> type your commands
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| 152 | ....
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| 153 | Idle> exit
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| 154 |
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| 155 | 7- USING HISTOGRAMS
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| 156 |
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| 157 | To use histograms, at least one of the AIDA implementations should be
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| 158 | available. See InstallAida.txt
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