$Id: README,v 1.9 2003/12/04 11:01:58 guatelli Exp $
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Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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xray_fluorescence
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XrayFluo is an advanced Geant4 example based on a realistic simulation of
a test beam.
The aim of the test beam was to characterize the response function of various
X-Rays detectors used to measure fluorescence emissions from samples composed
of different materials irradiated with a monochromatic beam of photons.
In this example the geometry of the detector is simplified:
one single pixel is used, since the test beams has used monolithic detectors.
The response function is tabulated for different values of incident
energy and stored in the file response.dat and SILIresponse.dat.
At the moment, two kinds of detectors are available: HPGe and Si(Li).
The sample, a simple box whose material can be selected, can be irradiated
with different particles, with different spectra for the incident energy and
with different shapes of the primary generator.
Apart from the sample and the detector there are two diaphragm reproducing
those used to collimate the incident beam during the test beam.
The aim of this advanced example is to illustrate the use of particle
generation and analysis schemes available in Geant4:
- the generation of particles is done via the G4ParticleGun: the example
shows how to use it in order to obtain a beam of circular section or
a particle source isotropic in space
_ the example includes the possibility to shoot particles according to a
given energy spectrum: the files B_flare.dat, C_Flare.dat and M_flare.dat
store the spectra of photons during solar flares, the files
mercury2_flx_solmax.dat and mercury_flx_solmin.dat contain the spectra of
protons respectively during solar maximum and solar minimum conditions, and
merc2_flx_alp_max.dat merc_flx_alp_min.dat contain the spectra of alpha
particles again respectively during solar maximum and solar minimum
conditions.
- histograming facilities are presently provided for the Linux environment
by using the AIDA3 interfaces.
The AIDA compliant version has not been tested by the developers and is
here as a example of "forward compatibility" on how to use analysis.
In order to be able to use any of these packages, prior installation is
necessary and a number of environment variables will have to be set.
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----> 2.SET-UP
|
-example enviroment with the compiler 3.2
-a standard Geant4 example GNUmakefile is provided |
setup with: |
compiler = gcc-3.2
G4SYSTEM = linux-g++ |
The following environment variables need to be set: |
G4LEDATA: points to low energy data base - G4EMLOW2.2 |
setup for analysis with AIDA 3.0/Anaphe 5.0.5 for user with account |
on lxplus:
|
setenv G4ANALYSIS_USE 1
source /afs/cern.ch/sw/lhcxx/share/LHCXX/5.0.5/scripts/setupAnaphe.csh
setenv PATH ${PATH}:/afs/cern.ch/sw/lhcxx/share/LHCXX/5.0.5/scripts/ |
Please take a look to the Anaphe/Lizard web page |
http://anaphe.web.cern.ch/anaphe
for more info
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To execute a sample simulation with visualisation of tracks
reaching the detector run:
XrayFluo
execute command "/control/execute xxxxx.mac"
If the analysis options are set, histograms will
automatically stored in the corresponding files (hbook or XML)
2. Detector description
The telescope and detector geometry is defined in
XrayFluoDetectorConstruction.cc
3. Detector peculiar properties are described in XrayFluoSiLiDetectorType and
XrayFluoHPGeDetectorType, both derived from XrayFluoVDetectorType. Other
detector types can be added, creating other implementations of
XrayFluoVDetectorType objects.
Detector type selection is made in XrayFluoDetectorConstruction, and can be
modified trough /apparate/detector command of the UI.
Other commands (apparate/sample /apparate/sampleGranularity
/apparate/GrainDiameter) are present to simulate sample granulosity:
grains are spheres, disposed in a compact cubic structure, i.e superipmposition
of planes of maximum density with ABC ABC path. The fundamental cell is of type
cubic with centered-faces.
4. Physics processes
The physics processes are in XrayFluoPhysicsList.cc
The main process in this example is fluorescence emission from the sample.
5. Event generation
This is done using the G4ParticleGun with some modifications. See
XrayFluoParticleGeneratorAction.cc
6. Analysis
At present the analisys is provided by any AIDA-3.0 compliant analysis system.
In the example the Anaphe toolkit (version 5.0.5) is used.
By setting visPlotter variable in XrayFluoAnalysisManager to true,
it is possible to display the simulated output of the detector while
simulation is in progress. Graph window is updated every 1000 events.
The example provides also a simple Python file used to display
histograms with Lizard 3.0.0.x
Various commads, with help, are available for Geant4 UI.
/analysis/outputFile and /analysis/fileType respectively for
changing the name and the type (xml or Hbook) of the file in wich results
are saved.
If these commends are used, to make the changes effective, another
command, /anaysis/update, must be executed.
NOTE: if a file named xrayfluo.hbk (default name) is present, it
will be deleted, even if /analysis/outputFile command is issued
before any run.
---- Last modified Susanna Guatelli 3/12/2003=======
Gabriele Cosmo