$Id: README,v 1.16 2006/05/30 12:36:46 maire Exp $
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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TestEm5
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How to study the transmission, absorption and reflexion of particles through
a single, thin or thick, layer of material.
In perticular, the effects of the multiple scattering can be ploted.
1- GEOMETRY DEFINITION
The "absorber" is a box made of a given material.
Three parameters define the absorber :
- the material of the absorber,
- the thickness of an absorber,
- the transverse size of the absorber (the input face is a square).
A volume "World" contains the "absorber".
In addition a transverse uniform magnetic field can be applied.
The default geometry is constructed in DetectorConstruction class, but all the
parameters can be changed via commands defined in the DetectorMessenger class.
The parameters of the "World" can be changed, too.
2- AN EVENT : THE PRIMARY GENERATOR
The primary kinematic consists of a single particle which hits the absorber
perpendicular to the input face. The type of the particle and its energy are
set in the PrimaryGeneratorAction class, and can be changed via the G4 build-in
commands of ParticleGun class (see the macros provided with this example).
In addition one can choose randomly the impact point of the incident particle.
The interactive command is built in PrimaryGeneratorMessenger class.
3- VISUALIZATION
The Visualization Manager is set in the main().
The initialisation of the drawing is done via the commands in vis.mac
In interactive session:
PreInit or Idle > /control/execute vis.mac
The example has a default view which is a longitudinal view of the detector.
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, or none.
This command is defined in EventActionMessenger class.
4- TRACKING
During the tracking, one can keep or not the secondaries : see StackingAction
class and its Messenger.
One can also limit 'by hand' the step lenght of the particle. As an example,
this limitation is implemented as a 'full' process : see StepMax class and its
Messenger. The 'StepMax process' is registered in the Physics List.
5- DETECTOR RESPONSE
At the end of a run, from the histogram(s), one can study different
physics quantities such as :
- energy deposit in the absorber,
- energy spectrum of secondaries at creation,
- energy spectrum and angle distribution of particles at exit,
- transmission and backscattering coefficients,
- ...
List of the built-in histograms
-------------------------------
The test contains 16 built-in 1D histograms, which are managed by the
HistoManager class and its Messenger. The histos can be individually activated
with the command :
/testem/histo/setHisto id nbBins valMin valMax unit
where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
(see the macros xxxx.mac).
1 "energy deposit in absorber"
2 "energy of charged secondaries at creation"
3 "energy of gammas at creation (log10(Ekin/MeV))"
4 "(transmit, charged) : kinetic energy at exit"
5 "(transmit, charged) : space angle at exit"
6 "(transmit, charged) : projected angle at exit"
7 "(transmit, charged) : projected position at exit"
8 "(transmit, neutral) : kinetic energy at exit"
9 "(transmit, neutral) : space angle at exit"
10 "(transmit, neutral) : projected angle at exit"
11 "(reflect , charged) : kinetic energy at exit"
12 "(reflect , charged) : space angle at exit"
13 "(reflect , charged) : projected angle at exit"
14 "(reflect , neutral) : kinetic energy at exit"
15 "(reflect , neutral) : space angle at exit"
16 "(reflect , neutral) : projected angle at exit"
The histograms can be viewed using PAW. See below the note on ANAPHE+AIDA.
One can control the name of the histograms file with the command:
/testem/histo/setFileName name (default testem5.hbook)
Note that, by default, histograms are disabled. To activate them, uncomment
the flag G4ANALYSIS_USE in GNUmakefile.
6- GEANT4/GEANT3/DATA COMPARISON
A Geant4/Geant3/exp. data comparison is given here for a few cases.
These cases can be classified as follow:
- e-/e+ incident particles versus protons and others.
- 3 energy regimes : low: < 1 MeV; medium: 1MeV -> few 10 MeV; high: > 100 MeV
We indicate here the corresponding macros.
| low energy | medium energy | high energy
--------------------------------------------------------
| acosta.mac | |
e-+ | berger.mac | hanson.mac |
| hunger.mac | kulchi.mac |
| tavola.mac | |
--------------------------------------------------------
others| bichsel.mac | vincour.mac | shen1.mac shen2.mac
| | gottsch.mac | tramu.mac
--------------------------------------------------------
The relevant part of the GEANT3 code is in the subdirectory geant3 together
with the xxxx.dat input files.
7- HOW TO START ?
- compile and link to generate an executable
% cd TestEm5
% gmake
- execute TestEm5 in 'batch' mode from macro files e.g.
% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5 myMacro.mac
- execute TestEm5 in 'interactive' mode with visualization e.g.
% $(G4INSTALL)/bin/$(G4SYSTEM)/TestEm5
Then type your commands, for instance :
Idle> control/execute vis.mac
Idle> run/beamOn 5
....
8- USING HISTOGRAMS
Note that, by default, histograms are disabled. To activate them, uncomment
the flag G4ANALYSIS_USE in GNUmakefile.
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