Gabriele Cosmo
209 lines
7.9 KiB
Plaintext
209 lines
7.9 KiB
Plaintext
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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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rdecay02
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--------
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Rdecay02 is created to show how to use the G4RadioactiveDecay process to
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simulate the decays of radioactive isotopes as well as the induced
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radioactivity resulted from nuclear interactions.
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In this example a simple geometry consists of a cylindric target placed
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in the centre of a tube detector. Various primary event generation and
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tallying options are available.
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1. GEOMETRY
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The world is filled with "Air" and there are two components in it:
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- Target: A cylinder placed at the origin along the z-axis. The default
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size of the cylinder is 0.5 cm radius and 1 cm length, and its default
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material is "CsI".
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- Detector: A tube centered at the origin along the z-axis, with inner
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radius matching the radius of the target. The default thickness of the
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tube is 2 cm and it is 5 cm long. The default material is "Germanium".
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The user can change the target/detector size and material, using the
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commands in the directory /rdecay02/det
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2. PHYSICS
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The following physics processes are included by default:
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- Standard electromagnetic
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- Decay
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- Radioactive Decay
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By default radioactive decay is applied through out the geometry.
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The user can limit it to just the target by commands :
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/process/had/rdm/noVolumes
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/process/had/rdm/selectVolume Target
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- Hadronic processes
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3. AN EVENT: THE PRIMARY GENERATOR
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The primary kinematic is a single particle or ion shooted at the
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centre of the target. The type of the particle and its energy are set in
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PrimaryGeneratorAction, and can be changed via the G4 build-in commands of
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ParticleGun class (see the macros provided with this example).
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Default is Ne24, at rest.
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4. DETECTOR RESPONSE
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The relevant informations are collected in TrackingAction or
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SteppingAction. These include:
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- Emission particles in the RadioactiveDecay process:
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particle PDGcode,
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particle kinetic energy,
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particle creation time,
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particle weight.
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Note: the residual nuclei is not considered as an emitted particle.
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- Radio-Isotopes. All the radioactive isotopes produced in the simulation:
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isotope PDGcode,
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isotope creation time,
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isotope weight.
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- Energy depositions in the target and detector by prodicts of the
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RadioactiveDecay process:
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energy depostion (positive value for target and negative for detector),
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time,
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weight.
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5. HISTOGRAMS
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The test contains 7 built-in 1D histograms, which are managed by
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G4AnalysisManager and its Messenger. The histos can be individually
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activated with the command :
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/analysis/h1/set id nbBins valMin valMax unit
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where unit is the desired unit for the histo (MeV or keV, etc..)
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(see the macros xxxx.mac).
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histogram 0: The Pulse Height Spectrum (PHS) of the target.
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histogram 1: The PHS of the detector.
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histogram 2: The combined PHS of the target and detector.
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histogram 3: The anti-coincidece PHS of the target.
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histogram 4: The anti-coincidece PHS of the detector.
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histogram 5: The coincidece PHS between the target and detector.
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histogram 6: The emitted particle energy spectrum.
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It is assumed the detector and target pulses both have an integration time
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of 1 microsecond, and the gate is 2 microsecond for the coincidence spectrum.
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The target and detctor have a threshold of 10 keV in the anti-/coincidence
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modes.
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Initially, all histograms but histogram 6 are inactive. They can all be turned on
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with the command
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/analysis/h1/setActivationToAll true
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or specific histograms can be turned on with the command
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/analysis/h1/setActivation i true
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where i is the histogram index (0,... n).
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To turn off, set the final argument to false
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HistoManager includes also 4 ntuples whose contents are described in the above paragraphe
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(detector response)
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The ntuples can be activated with the command /analysis/ntuple/setActivation
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One can control the name of the analysis file with the command:
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/analysis/setFileName name (default rdecay02)
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It is possible to choose the format of the histogram file : root (default),
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xml, csv, by using namespace in HistoManager.hh
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It is also possible to print selected histograms on an ascii file:
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/analysis/h1/setAscii id
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All selected histos will be written on a file name.ascii (default rdecay02)
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6. 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 commands
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/vis/... in the macro vis.mac. To get visualisation:
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> /control/execute vis.mac
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The tracks are drawn at the end of event, and erased at the end of run.
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gamma green
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neutron yellow
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negative particles (e-, ...) red
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positive particles (e+, ions, ...) blue
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7. HOW TO START ?
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Execute rdecay02 in 'batch' mode from macro files :
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% rdecay02 run1.mac
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Execute rdecay02 in 'interactive mode' with visualization :
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% rdecay02
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Idle> control/execute vis.mac
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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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8. FURTHER EXAMPLES
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There are a number of g4mac files in the ./macros subdirectory, to show
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the features of the G4RadioactiveDecay process. Most of them will lead to
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the creation of an root file in the same name of the macro file.
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u238c.mac: shows the decays of the U238 chain in analogue MC mode.
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th234c-b.mac: shows the decays of Th234 in variance reduction MC mode.
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All its secondaies in along the decay chains are generated. The default
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source profile and decay biasing schemes are used to determine the decay
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times and weights of the secondaries.
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proton.mac: simulation of 1 GeV protons incident on a lead target.
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The decays of the radio-siotopes created in the proton-lead interactions
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are simulated with RadioactiveDecay in analogue MC mode.
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proton-beam.mac: same as proton.mac, but the decays of the radio-siotopes
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created in the proton-lead interactions are simulated with
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RadioactiveDecay in variance reduction MC mode. The isotopes and those
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along the decay chains are forced to decay in the time windows specified
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by the user in file measures.data, and the weights of the decay products
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are determined by the beam profile as defined in the beam.data file and
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their decay times.
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neutron.mac: macrofile to show the incident of low energy neutrons on an
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user specified NaI target and the decays of the induced radio-isotopes.
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ne24.mac: this shows the decays of Ne-24 to Na-24 in variance reduction MC
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mode. Further decays of Na-24 are not simulated by applying the
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nucleuslimits in RadioactiveDecay. Two runs are carried out.
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One with the bracjing ratio biasing applied and one without.
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isotopes.mac: to show the decays of a number of different isotopes in a
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single macro file.
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f24.mac: to show the different treatments one can apply to the decays of F24.
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i) the complete decay chain from F24 to Mg24, in analogue mode;
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ii) the complete chain, but in variance reduction mode;
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iii) restrict to the decay of F24 only in analogue mode; iv) restrict to
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the decay of F24 only but in variance reduction mode.
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as74.mac: The decays of As74 which has a rather complicated decay scheme.
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i) in analogue MC mode;
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ii) in variance reduction MC mode.
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UserRadDataPb210Test.mac: show how the user can define its own radioactive
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decay datafile
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UserEvapDataBiTest.mac: show how the user can define its own
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photo-evaporation datafile
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No252.mac: show how to simulate Radoactive decay for nuclei with Z>100
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based on user datafile
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