$Id: README,v 1.14 2006/11/22 18:56:20 vnivanch Exp $
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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TestEm7
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How to produce a Bragg curve in a water phantom.
How to compute the dose in small 'test volumes' called tallies.
How to define a maximum step size.
1- GEOMETRY DEFINITION
The geometry consists of a single block of a homogenous material,
placed in a world.
Three parameters define the geometry :
- the material of the box,
- the thickness of the box (sizeX),
- the tranverse dimension of the box (sizeYZ).
The default is 20 cm of water.
In addition a transverse uniform magnetic field can be applied.
The default geometry is constructed in DetectorConstruction class,
but all of the above parameters can be changed interactively via
the commands defined in the DetectorMessenger class.
The size, matter, positions of several test-volumes (tallies) can be
defined via UI commands : /testem/det/tally...
2- PHYSICS LIST
Physics Lists are subdivided on 4 following modules:
1. "particles" - particle definitions
2. "general" - decays and transportation
The following options for EM physics are available:
- "standard" the best standard EM physics (default)
- "G4standard" recommended standard EM physics for LHC
- "G4standard_fast" the best CPU performance standard physics for LHC
- "Livermore" low-energy EM physics using Livermore data
- "Penelope" low-energy EM physics implementing Penelope models
Optional components can be added:
- "elastic" elastic scattering of hadrons
- "binary" QBBC configuration of hadron inelastic models
- "binary_ion" Binary ion inelastic models
Notice that there is an example of definition of a static ion : IonC12
(see PhysListParticle.cc) and an example of use : ionC12.mac
3- AN EVENT : THE PRIMARY GENERATOR
The primary kinematic consists of a single particle which hits the
block perpendicular to the input face. The type of the particle
and its energy are set in the PrimaryGeneratorAction class, and can
changed via the G4 build-in commands of ParticleGun class (see
the macros provided with this example).
The default is proton 160 MeV
In addition one can define randomly the impact point of the incident
particle. The corresponding interactive command is built in
PrimaryGeneratorMessenger class.
A RUN is a set of events.
4- VISUALIZATION
The Visualization Manager is set in the main().
The initialisation of the drawing is done via the command
> /control/execute vis.mac
The detector has a default view which is a longitudinal view of the box.
The tracks are drawn at the end of event, and erased at the end of run.
Optionaly one can choose to draw all particles, only the charged one,
or none. This command is defined in EventActionMessenger class.
5- HOW TO START ?
- compile and link to generate an executable
% cd geant4/examples/extended/electromagnetic/TestEm7
% gmake
- execute Test in 'batch' mode from macro files
% TestEm7 proton.mac
- execute Test in 'interactive mode' with visualization
% TestEm7
....
Idle> type your commands
....
Idle> exit
6- HISTOGRAM OF THE BRAGG PEAK
Testem7 computes the total energy deposited along the trajectory of
the incident particle : the so-called Bragg peak.
In order to control the accuracy of the deposition, the user can limit
the maximum allowed for the step size of charged particles.
(command /testem/stepMax )
The result is a 1D histogram which is the total energy deposited along
the trajectory of the incident particle.
The histogram is saved in hbook format (testem7.hbook)
The bin size is egal to stepMax. The number of bins is determined by
the thickness of the absorber (with a minimum of 100 bins).
The total energy deposited is plotted in MeV/mm per incident particle.
Note that, by default, histograms are disabled. To activate them, uncomment
G4ANALYSIS_USE in GNUmakefile.
7- DOSE IN 'TEST-VOLUMES'
The energy deposited in the test-volumes (tallies) defined in
DetectorConstruction are printed at EndOfRun, both in MeV and gray.
8- USING HISTOGRAMS
By default the histograms are not activated. To activate histograms
the environment variable G4ANALYSIS_USE should be defined. For instance
uncomment the flag G4ANALYSIS_USE in GNUmakefile.
It is possible to choose the format of the histogram file (hbook, root, XML):
comment/uncomment 1 line in RunAction::bookHisto().
Before compilation of the example it is optimal to clean up old files:
gmake histclean
gmake
To use histograms, at least one of the AIDA implementations should be
available (see http://aida.freehep.org).
8a - PI
A package including AIDA and extended interfaces also using Python is PI,
available from: http://cern.ch/pi
Once installed PI or PI-Lite in a specified local area $MYPY, it is required
to add the installation path to $PATH, i.e. for example, for release 1.2.1 of
PI:
setenv PATH ${PATH}:$MYPI/1.2.1/app/releases/PI/PI_1_2_1/rh73_gcc32/bin
CERN users can use the PATH to the LCG area on AFS.
Before running the example the command should be issued:
eval `aida-config --runtime csh`
8b - OpenScientist
OpenScientist is available at http://OpenScientist.lal.in2p3.fr.
You have to "setup" the OpenScientist AIDA implementation before compiling
(then with G4ANALYSIS_USE set) and running your Geant4 application.
On UNIX you setup, with a csh flavoured shell :
csh> source <<OpenScientist install path>/aida-setup.csh
or with a sh flavoured shell :
sh> . <<OpenScientist install path>/aida-setup.sh
On Windows :
DOS> call <<OpenScientist install path>/aida-setup.bat
You can use various file formats for writing (AIDA-XML, hbook, root).
These formats are readable by the Lab onx interactive program
or the OpenPAW application. See the web pages.
With OpenPAW, on a run.hbook file, one can view the histograms
with something like :
OS> opaw
opaw> h/file 1 run.hbook ( or opaw> h/file 1 run.aida or run.root)
opaw> zone 2 2
opaw> h/plot 1
opaw> h/plot 2
Gabriele Cosmo