Gabriele Cosmo
164 lines
5.6 KiB
Plaintext
164 lines
5.6 KiB
Plaintext
$Id: README,v 1.7 2004/06/23 11:29:50 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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TestEm7
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-------
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This example is devoted to the energy deposited by particles which
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are absorbed in a given material (Bragg peak).
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Also it computes the dose deposited in small 'test volumes' called tallies.
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In addition, it illustrates how to use the concept of 'process' in order
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to implement a constraint on the step size of the particle trajectories.
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1- GEOMETRY DEFINITION
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The geometry consists of a single block of a homogenous material,
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placed in a world.
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Three parameters define the geometry :
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- the material of the box,
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- the thickness of the box (sizeX),
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- the tranverse dimension of the box (sizeYZ).
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The default is 20 cm of water.
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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,
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but all of the above parameters can be changed interactively via
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the commands defined in the DetectorMessenger class.
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The size, matter, positions of several test-volumes (tallies) can be
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defined via UI commands : /testem/det/tally...
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2- PHYSICS LIST
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Physics Lists are subdivided on 4 following modules:
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1. "particles" - particle definitions
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2. "general" - decays and transportation
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3. "standard" (alternative) - standard EM physics
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4. "model" (alternative) - standard EM physics using model approach
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Notice that there is an example of definition of a static ion : IonC12
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(see PhysListParticle.cc) and an example of use : ionC12.mac
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3- AN EVENT : THE PRIMARY GENERATOR
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The primary kinematic consists of a single particle which hits the
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block perpendicular to the input face. The type of the particle
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and its energy are set in the PrimaryGeneratorAction class, and can
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changed via the G4 build-in commands of ParticleGun class (see
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the macros provided with this example).
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The default is proton 160 MeV
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In addition one can define randomly the impact point of the incident
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particle. The corresponding interactive command is built in
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PrimaryGeneratorMessenger class.
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A RUN is a set of events.
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4- 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 command
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> /control/execute vis.mac
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The detector has a default view which is a longitudinal view of the box.
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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 one,
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or none. This command is defined in EventActionMessenger class.
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5- HOW TO START ?
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- compile and link to generate an executable
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% cd geant4/examples/extended/electromagnetic/TestEm7
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% gmake
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- execute Test in 'batch' mode from macro files
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% TestEm7 run01.mac
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- execute Test in 'interactive mode' with visualization
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% TestEm7
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....
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Idle> type your commands
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....
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Idle> exit
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6- HISTOGRAM OF THE BRAGG PEAK
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Testem7 computes the total energy deposited along the trajectory of
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the incident particle : the so-called Bragg peak.
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In order to control the accuracy of the deposition, the user can limit
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the maximum allowed for the step size of charged particles.
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(command /testem/stepMax )
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The result is a 1D histogram which is the total energy deposited along
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the trajectory of the incident particle.
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The histogram is saved in paw (testem7.paw)
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The bin size is egal to stepMax. The number of bins is determined by
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the thickness of the absorber (with a minimum of 100 bins).
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The total energy deposited is plotted in MeV/mm.
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Note that, by default, histograms are disabled. To activate them, uncomment
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G4ANALYSIS_USE in GNUmakefile.
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7- DOSE IN 'TEST-VOLUMES'
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The energy deposited in the test-volumes (tallies) defined in
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DetectorConstruction are printed at EndOfRun, both in MeV and gray.
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Notice that the doses are not re initialized between runs, i.e. they are
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cumulative over the runs. (idem for the histogram of the Bragg peak.)
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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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