Gabriele Cosmo
182 lines
6.6 KiB
Plaintext
182 lines
6.6 KiB
Plaintext
$Id: README,v 1.12 2004/06/23 11:30:08 maire Exp $
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-----------------------------------------------------
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=========================================================
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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=========================================================
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TestEm5
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-------
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The purpose of this example is to study the transmission, absorption and
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reflexion of particles through a single, thin or thick, layer of material.
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In perticular, the effects of the multiple scattering can be easily ploted.
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1- GEOMETRY DEFINITION
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The "absorber" is a box made of a given material.
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Three parameters define the absorber :
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- the material of the absorber,
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- the thickness of an absorber,
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- the transverse size of the absorber (the input face is a square).
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A volume "World" contains the "absorber".
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In addition a transverse uniform magnetic field can be applied.
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The default geometry is constructed in DetectorConstruction class, but all the
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parameters can be changed via commands defined in the DetectorMessenger class.
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The parameters of the "World" can be changed, too.
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2- AN EVENT : THE PRIMARY GENERATOR
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The primary kinematic consists of a single particle which hits the absorber
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perpendicular to the input face. The type of the particle and its energy are
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set in the PrimaryGeneratorAction class, and can be changed via the G4 build-in
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commands of ParticleGun class (see the macros provided with this example).
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In addition one can choose randomly the impact point of the incident particle.
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The interactive command is built in PrimaryGeneratorMessenger class.
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3- VISUALIZATION
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The Visualization Manager is set in the main().
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The initialisation of the drawing is done via the commands in vis.mac
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In interactive session:
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PreInit or Idle > /control/execute vis.mac
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The example has a default view which is a longitudinal view of the detector.
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The tracks are drawn at the end of event, and erased at the end of run.
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Optionaly one can choose to draw all particles, only the charged, or none.
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This command is defined in EventActionMessenger class.
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4- TRACKING
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During the tracking, one can keep or not the secondaries : see StackingAction
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class and its Messenger.
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One can also limit 'by hand' the step lenght of the particle. As an example,
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this limitation is implemented as a 'full' process : see StepMax class and its
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Messenger. The 'StepMax process' is registered in the Physics List.
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5- DETECTOR RESPONSE
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At the end of a run, from the histogram(s), one can study different
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physics quantities such as :
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- energy deposit in the absorber,
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- energy spectrum of secondaries at creation,
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- energy spectrum and angle distribution of particles at exit,
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- transmission and backscattering coefficients,
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- ...
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List of the built-in histograms
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-------------------------------
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The test contains 16 built-in 1D histograms, which are managed by the
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HistoManager class and its Messenger. The histos can be individually activated
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with the command :
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/testem/histo/setHisto id nbBins valMin valMax unit
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where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
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(see the macros xxxx.mac).
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1 "energy deposit in absorber"
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2 "energy of charged secondaries at creation"
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3 "energy of gammas at creation (log10(Ekin/MeV))"
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4 "(transmit, charged) : kinetic energy at exit"
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5 "(transmit, charged) : space angle at exit"
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6 "(transmit, charged) : projected angle at exit"
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7 "(transmit, charged) : projected position at exit"
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8 "(transmit, neutral) : kinetic energy at exit"
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9 "(transmit, neutral) : space angle at exit"
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10 "(transmit, neutral) : projected angle at exit"
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11 "(reflect , charged) : kinetic energy at exit"
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12 "(reflect , charged) : space angle at exit"
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13 "(reflect , charged) : projected angle at exit"
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14 "(reflect , neutral) : kinetic energy at exit"
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15 "(reflect , neutral) : space angle at exit"
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16 "(reflect , neutral) : projected angle at exit"
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The histograms can be viewed using PAW. See below the note on ANAPHE+AIDA.
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One can control the name of the histograms file with the command:
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/testem/histo/setFileName name (default testem5.paw)
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Note that, by default, histograms are disabled. To activate them, uncomment
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the flag G4ANALYSIS_USE in GNUmakefile.
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6- GEANT4/GEANT3/DATA COMPARISON
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A Geant4/Geant3/exp. data comparison is given here for a few cases.
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These cases can be classified as follow:
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- e-/e+ incident particles versus protons and others.
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- 3 energy regimes : low: < 1 MeV; medium: 1MeV -> few 10 MeV; high: > 100 MeV
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We indicate here the corresponding macros.
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| low energy | medium energy | high energy
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--------------------------------------------------------
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e-+ | berger.mac | hanson.mac |
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| | kulchi.mac |
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--------------------------------------------------------
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others| bichsel.mac | vincour.mac | shen1.mac shen2.mac
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| | gottsch.mac | tramu.mac
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--------------------------------------------------------
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The relevant part of the GEANT3 code is in the subdirectory geant3 together
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with the xxxx.dat input files.
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7- HOW TO START ?
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- compile and link to generate an executable
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% cd TestEm5
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% gmake
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- execute TestEm5 in 'batch' mode from macro files e.g.
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% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 myMacro.mac
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- execute TestEm5 in 'interactive' mode with visualization e.g.
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% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5
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Then type your commands, for instance :
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Idle> control/execute vis.mac
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Idle> run/beamOn 5
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....
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8- Using histograms
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-------------------
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By default the histograms are not activated. To activate histograms
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the environment variable G4ANALYSIS_USE should be defined. For instance
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uncomment the flag G4ANALYSIS_USE in GNUmakefile.
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To use histograms any of implementations of AIDA interfaces should
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be available (see http://aida.freehep.org).
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A package including AIDA and extended interfaces also using Python
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is PI, available from: http://cern.ch/pi .
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Once installed PI or PI-Lite in a specified local area $MYPY, it is
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required to add the installation path to $PATH, i.e. for example,
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for release 1.2.1 of PI:
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setenv PATH ${PATH}:$MYPI/1.2.1/app/releases/PI/PI_1_2_1/rh73_gcc32/bin
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CERN users can use the PATH to the LCG area on AFS.
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Before compilation of the example it is optimal to clean up old
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files:
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gmake histclean
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gmake
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Before running the example the command should be issued:
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eval `aida-config --runtime csh`
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It is possible to choose the format of the output file with
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histograms using UI command:
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/testem/histo/setFileType type
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The following types are available: hbook, root, xml.
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