| 1 | $Id: README,v 1.26 2009/09/18 14:03:24 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 | TestEm5 |
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| 9 | ------- |
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| 10 | How to study the transmission, absorption and reflexion of particles through |
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| 11 | a single, thin or thick, layer of material. |
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| 12 | In perticular, the effects of the multiple scattering can be ploted. |
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| 13 | |
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| 14 | 1- GEOMETRY DEFINITION |
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| 15 | |
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| 16 | The "absorber" is a box made of a given material. |
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| 17 | |
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| 18 | Three parameters define the absorber : |
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| 19 | - the material of the absorber, |
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| 20 | - the thickness of an absorber, |
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| 21 | - the transverse size of the absorber (the input face is a square). |
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| 22 | |
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| 23 | A volume "World" contains the "absorber". |
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| 24 | |
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| 25 | In addition a transverse uniform magnetic field can be applied. |
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| 26 | |
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| 27 | The default geometry is constructed in DetectorConstruction class, but all the |
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| 28 | parameters can be changed via commands defined in the DetectorMessenger class. |
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| 29 | The parameters of the "World" can be changed, too. However, if World material |
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| 30 | is not set to vacuum, the plots 10->43 below may be not pertinent. |
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| 31 | |
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| 32 | 2- PHYSICS LIST |
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| 33 | |
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| 34 | Physics lists can be local (eg. in this example) or from G4 kernel |
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| 35 | physics_lists subdirectory. |
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| 36 | |
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| 37 | Local physics lists: |
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| 38 | - "local" standard EM physics with current 'best' options setting. |
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| 39 | these options are explicited in PhysListEmStandard |
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| 40 | - "standardSS" standard EM physics with single Coulomb scattering |
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| 41 | instead of multiple scattering |
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| 42 | |
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| 43 | From geant4/source/physics_lists/builders: |
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| 44 | - "emstandard_opt0" recommended standard EM physics for LHC |
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| 45 | - "emstandard_opt1" best CPU performance standard physics for LHC |
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| 46 | - "emstandard_opt2" |
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| 47 | - "emstandard_opt3" best current advanced EM options. |
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| 48 | analog to "local" above |
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| 49 | - "emlivermore" low-energy EM physics using Livermore data |
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| 50 | - "empenelope" low-energy EM physics implementing Penelope models |
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| 51 | |
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| 52 | Physics lists and options can be (re)set with UI commands |
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| 53 | |
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| 54 | Please, notice that options set through G4EmProcessOPtions are global, eg |
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| 55 | for all particle types. In G4 builders, it is shown how to set options per |
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| 56 | particle type. |
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| 57 | |
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| 58 | |
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| 59 | 3- AN EVENT : THE PRIMARY GENERATOR |
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| 60 | |
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| 61 | The primary kinematic consists of a single particle which hits the absorber |
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| 62 | perpendicular to the input face. The type of the particle and its energy are |
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| 63 | set in the PrimaryGeneratorAction class, and can be changed via the G4 build-in |
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| 64 | commands of ParticleGun class (see the macros provided with this example). |
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| 65 | |
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| 66 | In addition one can choose randomly the impact point of the incident particle. |
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| 67 | The interactive command is built in PrimaryGeneratorMessenger class. |
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| 68 | |
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| 69 | 4- VISUALIZATION |
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| 70 | |
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| 71 | The Visualization Manager is set in the main(). |
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| 72 | The initialisation of the drawing is done via the commands in vis.mac |
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| 73 | In interactive session: |
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| 74 | PreInit or Idle > /control/execute vis.mac |
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| 75 | |
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| 76 | The example has a default view which is a longitudinal view of the detector. |
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| 77 | |
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| 78 | The tracks are drawn at the end of event, and erased at the end of run. |
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| 79 | Optionaly one can choose to draw all particles, only the charged, or none. |
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| 80 | This command is defined in EventActionMessenger class. |
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| 81 | |
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| 82 | 5- TRACKING |
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| 83 | |
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| 84 | During the tracking, one can keep or not the secondaries : see StackingAction |
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| 85 | class and its Messenger. |
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| 86 | One can also limit 'by hand' the step lenght of the particle. As an example, |
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| 87 | this limitation is implemented as a 'full' process : see StepMax class and its |
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| 88 | Messenger. The 'StepMax process' is registered in the Physics List. |
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| 89 | |
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| 90 | 6- DETECTOR RESPONSE |
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| 91 | |
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| 92 | At the end of a run, from the histogram(s), one can study different |
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| 93 | physics quantities such as : |
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| 94 | - energy deposit in the absorber, |
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| 95 | - energy spectrum of secondaries at creation, |
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| 96 | - energy spectrum and angle distribution of particles at exit, |
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| 97 | - transmission and backscattering coefficients, |
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| 98 | - ... |
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| 99 | |
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| 100 | 7- List of the built-in histograms |
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| 101 | ---------------------------------- |
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| 102 | |
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| 103 | The test contains more than 20 built-in 1D histograms, which are managed by the |
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| 104 | HistoManager class and its Messenger. The histos can be individually activated |
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| 105 | with the command : |
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| 106 | /testem/histo/setHisto id nbBins valMin valMax unit |
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| 107 | where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..) |
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| 108 | (see the macros xxxx.mac). |
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| 109 | |
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| 110 | 1 "energy deposit in absorber" |
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| 111 | 2 "energy of charged secondaries at creation" |
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| 112 | 3 "energy of gammas at creation (log10(Ekin/MeV))" |
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| 113 | 4 "x_vertex of charged secondaries (all)" |
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| 114 | 5 "x_vertex of charged secondaries (not absorbed)" |
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| 115 | 10 "(transmit, charged) : kinetic energy at exit of world" |
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| 116 | 11 "(transmit, charged) : ener fluence: dE(MeV)/dOmega" |
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| 117 | 12 "(transmit, charged) : space angle dN/dOmega" |
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| 118 | 13 "(transmit, charged) : projected angle at exit of world" |
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| 119 | 14 "(transmit, charged) : projected position at exit of world" |
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| 120 | 15 "(transmit, charged) : radius at exit of world" |
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| 121 | 20 "(transmit, neutral) : kinetic energy at exit of world" |
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| 122 | 21 "(transmit, neutral) : ener fluence: dE(MeV)/dOmega" |
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| 123 | 22 "(transmit, neutral) : space angle dN/dOmega" |
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| 124 | 23 "(transmit, neutral) : projected angle at exit of world" |
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| 125 | 30 "(reflect , charged) : kinetic energy at exit of world" |
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| 126 | 31 "(reflect , charged) : ener fluence: dE(MeV)/dOmega" |
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| 127 | 32 "(reflect , charged) : space angle dN/dOmega" |
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| 128 | 33 "(reflect , charged) : projected angle at exit of world" |
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| 129 | 40 "(reflect , neutral) : kinetic energy at exit of world" |
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| 130 | 41 "(reflect , neutral) : ener fluence: dE(MeV)/dOmega" |
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| 131 | 42 "(reflect , neutral) : space angle dN/dOmega" |
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| 132 | 43 "(reflect , neutral) : projected angle at exit of world" |
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| 133 | |
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| 134 | The histograms can be viewed using ROOT or PAW. See below the note on AIDA. |
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| 135 | |
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| 136 | One can control the name and format of the histograms file with the command: |
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| 137 | /testem/histo/setFileName name (default testem5) |
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| 138 | /testem/histo/setFileType type (choice: hbook, root(default), XML) |
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| 139 | |
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| 140 | It is also possible to print selected histograms on an ascii file: |
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| 141 | /testem/histo/printHisto id |
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| 142 | All selected histos will be written on a file name.ascii (default testem5) |
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| 143 | |
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| 144 | Note that, by default, histograms are disabled. To activate them, uncomment |
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| 145 | the flag G4ANALYSIS_USE in GNUmakefile. |
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| 146 | |
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| 147 | 8- GEANT4/GEANT3/DATA COMPARISON |
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| 148 | |
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| 149 | A Geant4/Geant3/exp. data comparison is given here for a few cases. |
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| 150 | These cases can be classified as follow: |
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| 151 | - e-/e+ incident particles versus protons and others. |
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| 152 | - 3 energy regimes: low: < 1MeV; medium: 1MeV -> few 10MeV; high: > 100MeV |
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| 153 | |
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| 154 | We indicate here the corresponding macros. |
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| 155 | |
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| 156 | | low energy | medium energy | high energy |
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| 157 | -------------------------------------------------------- |
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| 158 | | acosta.mac | | |
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| 159 | e-+ | berger.mac | hanson.mac | |
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| 160 | | hunger.mac | kulchi.mac | |
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| 161 | | tavola.mac | | |
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| 162 | -------------------------------------------------------- |
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| 163 | others| bichsel.mac | vincour.mac | shen1.mac shen2.mac |
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| 164 | | | gottsch.mac | tramu.mac |
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| 165 | -------------------------------------------------------- |
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| 166 | |
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| 167 | The relevant part of the GEANT3 code is in the subdirectory geant3 together |
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| 168 | with the xxxx.dat input files. |
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| 169 | |
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| 170 | 9- HOW TO START ? |
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| 171 | |
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| 172 | - compile and link to generate an executable |
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| 173 | % cd TestEm5 |
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| 174 | % gmake |
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| 175 | |
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| 176 | - execute TestEm5 in 'batch' mode from macro files e.g. |
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| 177 | % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 myMacro.mac |
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| 178 | |
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| 179 | - execute TestEm5 in 'interactive' mode with visualization e.g. |
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| 180 | % $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 |
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| 181 | Then type your commands, for instance : |
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| 182 | Idle> control/execute vis.mac |
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| 183 | Idle> run/beamOn 5 |
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| 184 | .... |
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| 185 | |
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| 186 | 10- USING HISTOGRAMS |
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| 187 | |
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| 188 | Note that, by default, histograms are disabled. To activate them, uncomment |
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| 189 | the flag G4ANALYSIS_USE in GNUmakefile. |
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| 190 | |
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| 191 | Before compilation of the example it is optimal to clean up old files: |
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| 192 | gmake histclean |
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| 193 | gmake |
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| 194 | |
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| 195 | To use histograms, at least one of the AIDA implementations should be |
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| 196 | available. See InstallAida.txt |
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| 197 | |
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