Gabriele Cosmo
174 lines
7.3 KiB
Plaintext
174 lines
7.3 KiB
Plaintext
$Id: README,v 1.14 2005/12/09 22:15:52 mantero 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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xray_fluorescence
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-----------------
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XrayFluo is an advanced Geant4 example based on a realistic simulation of
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a test beam.
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The aim of the test beam was to characterize the response function of various
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X-Rays detectors used to measure fluorescence emissions from samples composed
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of different materials irradiated with a monochromatic beam of photons.
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In this example the geometry of the detector is simplified:
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one single pixel is used, since the test beams has used monolithic detectors.
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The response function is tabulated for different values of incident
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energy and stored in the file response.dat and SILIresponse.dat.
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At the moment, two kinds of detectors are available: HPGe and Si(Li).
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The sample, a simple box whose material can be selected, can be irradiated
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with different particles, with different spectra for the incident energy and
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with different shapes of the primary generator.
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Apart from the sample and the detector there are two diaphragm reproducing
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those used to collimate the incident beam during the test beam.
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The aim of this advanced example is to illustrate the use of particle
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generation and analysis schemes available in Geant4:
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- the generation of particles is done via the G4ParticleGun: the example
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shows how to use it in order to obtain a beam of circular section or
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a particle source isotropic in space
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- the example includes the possibility to shoot particles according to a
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given energy spectrum: the files B_flare.dat, C_Flare.dat and M_flare.dat
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store the spectra of photons during solar flares, the files
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mercury2_flx_solmax.dat and mercury_flx_solmin.dat contain the spectra of
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protons respectively during solar maximum and solar minimum conditions, and
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merc2_flx_alp_max.dat merc_flx_alp_min.dat contain the spectra of alpha
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particles again respectively during solar maximum and solar minimum
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conditions.
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- histograming facilities are presently provided for the Linux environment
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by using the AIDA3 interfaces.
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The AIDA compliant version has not been tested by the developers and is
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here as a example of "forward compatibility" on how to use analysis.
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In order to be able to use any of these packages, prior installation is
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necessary to configure you environment to get visulaization, as described in geant4 manual.
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If we want to use analisys, we provide an example for the use of PI:
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# flag that we want to use analysis:
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setenv G4ANALYSIS_USE 1
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#select AIDA implementation: PI 1.3.3
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setenv G4ANALYSIS_BUILD 1
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setenv PI_VERSION 1_3_3
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setenv PATH /your/path/to/PI/app/releases/PI/PI_1_3_0/slc3_ia32_gcc323/bin/:${PATH}
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eval `aida-config -r csh`
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#path to the lowEnergy data base
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setenv G4LEDATA /your/path/to/geant4/data/G4EMLOW3.0
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#path to Xray_Fluorescence data files, if not set, PWD is assumed:
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setenv XRAYDATA /path/to/detector/and/input/spctra/files
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1. Run
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After the compilation of the program, to execute a sample simulation type (for example):
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$G4WORKDIR/bin/Linux-g++/XrayFluo
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The program gives, at tis point,the user 4 options:
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Please Select Simulation Geometrical Set-Up:
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1 - Test Beam
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2 - Infinite Plane
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3 - Planet and Sun
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4 - Phase-Space Production
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The first three choices are to choose different experimental set-ups
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(a test beam one, an infite plane and a planetary geometry), while
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the fourth is a simplified version of the first, without a detector,
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only to generate a tuple with particles genereted or exiting the sample.
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In order to run a macro, type the following command:
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idle> execute command "/control/execute xxxxx.mac"
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If the analysis options are set, histograms will
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automatically stored in the corresponding files (hbook or XML)
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In order to launch the application in batch mode, it is necessary to specify,
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after the executable file name, the name of the macro file and the number of the choice:
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$G4WORKDIR/bin/Linux-g++/XrayFluo xxxxx.mac 1
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2. Detector description
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The telescope and detector geometry is defined in
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XrayFluoDetectorConstruction.cc
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3. Detector peculiar properties are described in XrayFluoSiLiDetectorType and
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XrayFluoHPGeDetectorType, both derived from XrayFluoVDetectorType. Other
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detector types can be added, creating other implementations of
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XrayFluoVDetectorType objects.
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Detector type selection is made in XrayFluoDetectorConstruction, and can be
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modified trough /apparate/detector command of the UI.
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Other commands (apparate/sample /apparate/sampleGranularity
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/apparate/GrainDiameter) are present to simulate sample granulosity:
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grains are spheres, disposed in a compact cubic structure, i.e superipmposition
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of planes of maximum density with ABC ABC path. The fundamental cell is of type
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cubic with centered-faces.
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4. Physics processes
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The physics processes are in XrayFluoPhysicsList.cc
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The main process in this example is fluorescence emission from the sample.
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5. Event generation
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This is done using the G4ParticleGun with some modifications. See
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XrayFluoParticleGeneratorAction.cc
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Event generation is controlled by commands in the /gun/category (see help for further details).
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In this readme only two commands are undrlined:
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- /gun/loadGunData <filename>: to be used with the setup #1, loads the ntuple created
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in the setup #4. The loaded particles will be generated and will be directed
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ALL OF THEM to the detector. This can be useful to perform detector studies
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with encreased efiiciency.
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- /gun/loadRayleighFlag <true/false> This is used to let the user decide if backscattered
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primary particles should be loaded and directed toward the detector. This command,
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in order to be useful, must be used BEFORE the previous one.
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6. Analysis
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At present the analisys is provided by any AIDA-3.2.1 compliant analysis system.
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In the example the Anaphe toolkit is used.
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AIDA implementation configuration for compilation and link are in GNUmakefile, once
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is set the environmente as above:
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ifdef G4ANALYSIS_USE
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CPPFLAGS += `aida-config --include`
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LDFLAGS += `aida-config --lib`
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LOADLIBS += `aida-config --lib`
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endif
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To build and execute the example on platforms where there is no
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implementation of the analysis system, the environment variable
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G4ANALYSIS_USE must not be set.
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By setting visPlotter variable in XrayFluoAnalysisManager to true,
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it is possible to display the simulated output of the detector while
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simulation is in progress. Graph window is updated every 1000 events.
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The example provides also a simple Python file (readPY) used to display
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histograms with the python interface of PI. This must be run after the
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configuration script config.csh and the python interpreter.
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Various commads, with help, are available for Geant4 UI.
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/analysis/outputFile and /analysis/fileType respectively for
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changing the name and the type (xml or Hbook) of the file in wich results
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are saved.
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If these commends are used, to make the changes effective, another
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command, /anaysis/update, must be executed.
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NOTE: if a file named xrayfluo.hbk (default name) is present, it
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will be deleted, even if /analysis/outputFile command is issued
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before any run.
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