| 1 | $Id: README,v 1.33 2009/09/17 20:06:26 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 | TestEm3 |
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| 9 | ------- |
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| 10 | |
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| 11 | How to collect energy deposition in a sampling calorimeter. |
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| 12 | How to survey energy flow. |
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| 13 | how to print stopping power. |
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| 14 | |
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| 15 | 1- GEOMETRY DEFINITION |
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| 16 | |
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| 17 | The calorimeter is a box made of a given number of layers. |
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| 18 | A layer consists of a sequence of various absorbers (maximum MaxAbsor=9). |
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| 19 | The layer is replicated. |
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| 20 | |
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| 21 | Parameters defining the calorimeter : |
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| 22 | - the number of layers, |
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| 23 | - the number of absorbers within a layer, |
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| 24 | - the material of the absorbers, |
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| 25 | - the thickness of the absorbers, |
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| 26 | - the transverse size of the calorimeter (the input face is a square). |
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| 27 | |
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| 28 | In addition a transverse uniform magnetic field can be applied. |
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| 29 | |
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| 30 | The default geometry is constructed in DetectorConstruction class, but all |
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| 31 | of the above parameters can be modified interactively via the commands |
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| 32 | defined in the DetectorMessenger class. |
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| 33 | |
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| 34 | |
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| 35 | |<----layer 0---------->|<----layer 1---------->|<----layer 2---------->| |
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| 36 | | | | | |
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| 37 | ========================================================================== |
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| 38 | || | || | || | || |
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| 39 | || | || | || | || |
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| 40 | || abs 1 | abs 2 || abs 1 | abs 2 || abs 1 | abs 2 || |
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| 41 | || | || | || | || |
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| 42 | || | || | || | || |
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| 43 | beam || | || | || | || |
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| 44 | ======> || | || | || | || |
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| 45 | || | || | || | || |
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| 46 | || | || | || | || |
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| 47 | || | || | || | || |
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| 48 | || | || | || | || |
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| 49 | || cell 1 | cell 2|| cell 3 | cell 4|| cell 5 | cell 6|| |
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| 50 | ========================================================================== |
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| 51 | ^ ^ ^ ^ ^ ^ ^ |
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| 52 | pln1 pln2 pln3 pln4 pln5 pln6 pln7 |
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| 53 | |
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| 54 | NB. The number of absorbers and the number of layers can be set to 1. |
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| 55 | In this case we have a unique homogeneous block of matter, which looks like |
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| 56 | a bubble chamber rather than a calorimeter ... |
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| 57 | (see the macro of commands: newgeom.mac) |
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| 58 | |
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| 59 | 2- PHYSICS LISTS |
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| 60 | |
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| 61 | Physics lists can be local (eg. in this example) or from G4 kernel |
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| 62 | physics_lists subdirectory. |
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| 63 | |
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| 64 | Local physics lists: |
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| 65 | - "local" standard EM physics with current 'best' options setting. |
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| 66 | these options are explicited in PhysListEmStandard |
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| 67 | |
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| 68 | From geant4/source/physics_lists/builders: |
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| 69 | - "emstandard_opt0" recommended standard EM physics for LHC |
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| 70 | - "emstandard_opt1" best CPU performance standard physics for LHC |
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| 71 | - "emstandard_opt2" |
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| 72 | - "emstandard_opt3" best current advanced EM options. |
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| 73 | analog to "local" above |
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| 74 | - "emlivermore" low-energy EM physics using Livermore data |
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| 75 | - "empenelope" low-energy EM physics implementing Penelope models |
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| 76 | |
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| 77 | Physics lists and options can be (re)set with UI commands |
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| 78 | |
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| 79 | Please, notice that options set through G4EmProcessOPtions are global, eg |
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| 80 | for all particle types. In G4 builders, it is shown how to set options per |
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| 81 | particle type. |
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| 82 | |
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| 83 | 3- AN EVENT : THE PRIMARY GENERATOR |
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| 84 | |
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| 85 | The primary kinematic consists of a single particle which hits the calorimeter |
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| 86 | perpendicular to the input face. The type of the particle and its energy are |
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| 87 | set in the PrimaryGeneratorAction class, and can be changed via the |
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| 88 | G4 build-in commands of ParticleGun class (see the macros provided with this |
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| 89 | example). |
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| 90 | |
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| 91 | In addition one can choose randomly the impact point of the incident particle. |
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| 92 | The corresponding interactive command is built in PrimaryGeneratorMessenger. |
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| 93 | |
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| 94 | A RUN is a set of events. |
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| 95 | |
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| 96 | TestEm3 computes the energy deposited per absorber and the energy flow through |
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| 97 | the calorimeter |
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| 98 | |
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| 99 | 4- VISUALIZATION |
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| 100 | |
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| 101 | The Visualization Manager is set in the main(). |
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| 102 | The initialisation of the drawing is done via the commands : |
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| 103 | /vis/... in the macro vis.mac. In interactive session: |
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| 104 | PreInit or Idle > /control/execute vis.mac |
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| 105 | |
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| 106 | The default view is a longitudinal view of the calorimeter. |
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| 107 | |
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| 108 | The tracks are drawn at the end of event, and erased at the end of run. |
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| 109 | Optionaly one can choose to draw all particles, only the charged one, or none. |
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| 110 | This command is defined in EventActionMessenger class. |
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| 111 | |
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| 112 | 5- PHYSICS DEMO |
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| 113 | |
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| 114 | The particle's type and the physic processes which will be available |
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| 115 | in this example are set in PhysicsList class. |
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| 116 | |
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| 117 | In addition a build-in interactive command (/process/inactivate processName) |
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| 118 | allows to activate/inactivate the processes one by one. |
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| 119 | Then one can well visualize the processes one by one, especially |
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| 120 | in the bubble chamber setup with a transverse magnetic field. |
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| 121 | |
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| 122 | As a homework try to visualize a gamma conversion alone, |
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| 123 | or the effect of the multiple scattering. |
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| 124 | |
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| 125 | Notice that one can control the maximum step size in each absorber, via the |
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| 126 | StepMax process and the command /testem/stepMax/absorber |
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| 127 | (see StepMax and PhysicsList classes) |
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| 128 | |
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| 129 | 6- HOW TO START ? |
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| 130 | |
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| 131 | - compile and link to generate an executable |
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| 132 | % cd TestEm3 |
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| 133 | % gmake |
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| 134 | |
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| 135 | - execute TestEm3 in 'batch' mode from macro files |
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| 136 | % TestEm3 run01.mac |
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| 137 | |
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| 138 | - execute TestEm3 in 'interactive mode' with visualization |
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| 139 | % TestEm3 |
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| 140 | .... |
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| 141 | Idle> type your commands. For instance: |
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| 142 | Idle> /control/execute run01.mac |
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| 143 | .... |
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| 144 | Idle> exit |
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| 145 | |
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| 146 | 7- HISTOGRAMS |
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| 147 | |
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| 148 | Testem3 can produce histograms : |
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| 149 | histo 1 : energy deposit in absorber 1 |
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| 150 | histo 2 : energy deposit in absorber 2 |
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| 151 | ...etc........... |
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| 152 | |
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| 153 | One can control the binning of the histo with the command: |
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| 154 | /testem/histo/setHisto idAbsor nbin Emin Emax unit |
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| 155 | ...etc........... |
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| 156 | where unit is the desired energy unit for that histo (see TestEm3.in). |
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| 157 | |
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| 158 | histo 11 : longitudinal profile of energy deposit in absorber 1 (MeV/event) |
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| 159 | histo 12 : longitudinal profile of energy deposit in absorber 2 (MeV/event) |
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| 160 | ...etc........... |
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| 161 | |
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| 162 | histo 21 : energy flow (MeV/event) |
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| 163 | histo 22 : lateral energy leak (MeV/event) |
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| 164 | |
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| 165 | One can control the name of the histograms file with the commands: |
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| 166 | /testem/histo/setFileName name (default testem3) |
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| 167 | /testem/histo/setFileType type (choice: hbook, root(default), XML) |
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| 168 | |
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| 169 | NB. Numbering scheme for histograms: |
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| 170 | layer : from 1 to NbOfLayers (inclued) |
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| 171 | absorbers : from 1 to NbOfAbsor (inclued) |
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| 172 | planes : from 1 to NbOfLayers*NbOfAbsor + 1 (inclued) |
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| 173 | |
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| 174 | It is also possible to print selected histograms on an ascii file: |
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| 175 | /testem/histo/printHisto id |
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| 176 | All selected histos will be written on a file name.ascii (default testem3) |
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| 177 | |
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| 178 | Note that, by default, histograms are disabled. To activate them, uncomment |
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| 179 | the flag G4ANALYSIS_USE in GNUmakefile. |
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| 180 | |
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| 181 | Before compilation of the example it is optimal to clean up old files: |
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| 182 | gmake histclean |
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| 183 | gmake |
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| 184 | |
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| 185 | |
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| 186 | 8- USING HISTOGRAMS |
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| 187 | |
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| 188 | To use histograms, at least one of the AIDA implementations should be |
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| 189 | available. See InstallAida.txt |
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| 190 | |
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