Gabriele Cosmo
180 lines
6.5 KiB
Markdown
180 lines
6.5 KiB
Markdown
\page ExampleActivation Example Activation
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Survey energy deposition and particle's flux from an hadronic cascade,
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including radioactive decays.
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The main purpose of the example is to plot evolution of each metastable isomer
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as a function of time, taking into account the time of exposure in the beam.
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Also plot the activity of emerging particles.
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Use PhysicsConstructor objects rather than predefined G4 PhysicsLists.
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## MATERIALS AND GEOMETRY DEFINITION
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The "absorber" is a box made of a given material.
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Three parameters define the absorber :
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- the material of the absorber
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- the thickness of an absorber
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- the transverse size of the absorber (the input face is a square)
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The volume "World" contains the "absorber".
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A function, and its associated UI command, allows to build a material
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directly from a single isotope.
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To be identified by the ThermalScattering module, the elements composing a
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material must have a specific name (see G4ParticleHPThermalScatteringNames.cc)
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Examples of such materials are build in DetectorConstruction::DefineMaterials().
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## PHYSICS LIST
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The physics list contains a "full" set of physics processes. It is defined in
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the PhysicsList class as a Geant4 modular physics list with registered physics
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constructors (builders).
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Physics constructors are either constructors provided in Geant4 (with G4 prefix)
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or 'local'. They include : HadronElastic, HadronInelastic, IonsInelastic, GammaNuclear,
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RadioactiveDecay and Electomagnetic.
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(see geant4/source/physics_lists/constructors)
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HadronElasticPhysicsHP include a model for thermalized neutrons, under the control of a command
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defined in NeutronHPMesseger.
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GammmaNuclearPhysics is a subset of G4BertiniElectroNuclearBuilder.
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ElectromagneticPhysics is a simplified version of G4EmStandardPhysics.
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Several hadronic physics options are controlled by environment variables.
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To select them, see Activation.cc
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## AN EVENT : THE PRIMARY GENERATOR
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The primary kinematic is a single particle which hits the absorber
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perpendicular to the input face. The type of particle and its energy are
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set in the PrimaryGeneratorAction class, and can be changed via the G4
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build-in commands of G4ParticleGun class
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(see the macros provided with this example).
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One can control the transverse size of the beam.
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The command
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```
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/testhadr/gun/beamSize
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```
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is built in PrimaryGeneratorMessenger class.
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The time of exposure in the beam may be finite. It is controled by the command
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```
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/testhadr/gun/beamTime.
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```
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Then the time zero of each event is randomly chosen within this interval.
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## PHYSICS
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The program computes and plots energy deposited in the interaction volume
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(absorber), energy spectrum and activity of particles leaving the absorber,
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and evolution of population of metastable isomers within the absorber
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(see below : histograms).
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Processes invoked and particles generated during interactions are listed.
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## HISTOGRAMS
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The test contains 43 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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```
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/analysis/h1/set id nbBins valMin valMax unit
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```
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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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- 1 : "total energy deposit"
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- 2 : "Edep (MeV/mm) profile along beam direction"
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- 3 : "total kinetic energy emerging"
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- 4 : "energy spectrum of emerging gamma"
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- 5 : "energy spectrum of emerging e+-"
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- 6 : "energy spectrum of emerging neutrons"
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- 7 : "energy spectrum of emerging protons"
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- 8 : "energy spectrum of emerging deuterons"
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- 9 : "energy spectrum of emerging alphas"
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- 10: "energy spectrum of all others emerging ions"
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- 11: "energy spectrum of all others emerging baryons"
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- 12: "energy spectrum of all others emerging mesons"
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- 13: "energy spectrum of all others emerging leptons (neutrinos)"
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- 14: "dN/dt (becquerel) of emerging gamma"
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- 15: "dN/dt (becquerel) of emerging e+-"
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- 16: "dN/dt (becquerel) of emerging neutrons"
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- 17: "dN/dt (becquerel) of emerging protons"
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- 18: "dN/dt (becquerel) of emerging deuterons"
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- 19: "dN/dt (becquerel) of emerging alphas"
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- 20: "dN/dt (becquerel) of all others emerging ions"
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- 21: "dN/dt (becquerel) of all others emerging baryons"
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- 22: "dN/dt (becquerel) of all others emerging mesons"
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- 23: "dN/dt (becquerel) of all others emerging leptons (neutrinos)"
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Histograms 24 to 43 are assigned to population of metastable isomer.
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Here, ´metastable' means time life > 0.
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The type and number of isomers created in a run cannot be predicted in advance.
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Therefore the assignation : isomer <--> histo_Id is done on fly
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and printed at end of run. A lock mechanism is necessary in MT mode; see Run.cc
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Activation and binning control of histograms is done with the usual command
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```
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/analysis/h1/set
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```
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One can control the name of the histograms file with the command:
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```
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/analysis/setFileName name (default Activation)
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```
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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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```
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/analysis/h1/setAscii id
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```
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All selected histos will be written on a file name.ascii (default Activation)
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## 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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```
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> /control/execute vis.mac
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```
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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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## HOW TO START ?
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Execute Activation in 'batch' mode from macro files :
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```
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% ./Activation run.mac
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% ./Activation Activation.in > Activation.out
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```
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Execute Activation in 'interactive mode' with visualization :
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```
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% ./Activation
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Idle> control/execute debug.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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```
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Macros provided in this example:
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- Bi209.mac: neutron (25 meV) on 10 cm of Bi209
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- Co60.mac: neutron (25 meV) on 1 cm of Cobalt.
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- run.mac: simplified Co60.mac (no beam time, no histograms)
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Macros to be run interactively:
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- vis.mac: To activate visualization
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- debug.mac: 1 neutron (25 meV) on Cobalt. Visualization and tracking/verbose |