Gabriele Cosmo
173 lines
7.1 KiB
Plaintext
173 lines
7.1 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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Hadr05
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------
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How to collect energy deposition in a sampling calorimeter.
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How to survey energy flow.
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Hadr05 is the hadronic equivalent of TestEm3.
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1- GEOMETRY DEFINITION
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The calorimeter is a box made of a given number of layers.
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A layer consists of a sequence of various absorbers (maximum MaxAbsor=9).
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The layer is replicated.
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Parameters defining the calorimeter :
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- the number of layers,
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- the number of absorbers within a layer,
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- the material of the absorbers,
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- the thickness of the absorbers,
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- the transverse size of the calorimeter (the input face is a square).
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In addition a transverse uniform magnetic field can be applied.
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The default geometry is constructed in DetectorConstruction class, but all
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of the above parameters can be modified interactively via the commands
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defined in the DetectorMessenger class.
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|<----layer 0---------->|<----layer 1---------->|<----layer 2---------->|
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==========================================================================
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|| | || | || | ||
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|| abs 1 | abs 2 || abs 1 | abs 2 || abs 1 | abs 2 ||
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beam || | || | || | ||
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======> || | || | || | ||
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|| cell 1 | cell 2 || cell 3 | cell 4 || cell 5 | cell 6 ||
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==========================================================================
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^ ^ ^ ^ ^ ^ ^
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pln1 pln2 pln3 pln4 pln5 pln6 pln7
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NB. The number of absorbers and the number of layers can be set to 1.
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In this case we have a unique homogeneous block of matter, which looks like
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a bubble chamber rather than a calorimeter ...
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(see the macro emtutor.mac)
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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 Hadr06/src/DetectorConstruction.cc
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2- PHYSICS LISTS
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"Full" set of physics processes are registered, but via PhysicsConstructor
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objects rather than complete pre-defined G4 physics lists. This alternative
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way gives more freedom to register physics.
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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,
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GammaNuclear, RadioactiveDecay and Electomagnetic.
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(see geant4/source/physics_lists/constructors)
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HadronElasticPhysicsHP include a model for thermalized neutrons,
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under the control of the command /testhadr/phys/thermalScattering
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GammmaNuclearPhysics is a subset of G4BertiniElectroNuclearBuilder.
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ElectromagneticPhysics is a readable version of G4EmStandardPhysics_opt3.
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Several hadronic physics options are controlled by environment variables.
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To select them, see Hadr07.cc
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3- AN EVENT : THE PRIMARY GENERATOR
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The primary kinematic consists of a single particle which hits the calorimeter
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perpendicular to the input face. The type of the particle and its energy are
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set in the PrimaryGeneratorAction class, and can be changed via the
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G4 build-in commands of G4ParticleGun class (see the macros provided with this
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example).
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In addition one can choose randomly the impact point of the incident particle.
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The corresponding interactive command is built in PrimaryGeneratorAction.
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A RUN is a set of events.
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Hadr05 computes the energy deposited per absorber and the energy flow through
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the calorimeter.
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4- VISUALIZATION
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The Visualization Manager is set in the main() (see Hadr05.cc).
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The initialisation of the drawing is done via the commands :
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/vis/... in the macro vis.mac. In interactive session:
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PreInit or Idle > /control/execute vis.mac
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The default view is a longitudinal view of the calorimeter.
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5- PHYSICS DEMO
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The particle's type and the physics processes which will be available
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in this example are set in PhysicsList class.
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In addition a built-in interactive command (/process/inactivate processName)
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allows to activate/inactivate the processes one by one.
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Then one can well visualize the processes one by one, especially
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in the bubble chamber setup with a transverse magnetic field.
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6- HOW TO START ?
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- Execute Hadr05 in 'batch' mode from macro files
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% Hadr05 Cu-lAr.mac
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- Execute Hadr05 in 'interactive mode' with visualization
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% Hadr05
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....
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Idle> type your commands. For instance:
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Idle> /control/execute vis.mac
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....
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Idle> exit
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Macros provided in this example:
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- Fe-Sci.mac, Cu-lAr.mac, Pb-lAr.mac, W-lAr.mac : names are self explanatory
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- emtest.mac, emtutor.mac : to be run interactively
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- vis.mac: to activate visualization
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7- HISTOGRAMS
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Hadr05 can produce histograms :
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histo 1 : energy deposit in absorber 1
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histo 2 : energy deposit in absorber 2
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...etc...........
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histo 11 : longitudinal profile of energy deposit in absorber 1 (MeV/event)
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histo 12 : longitudinal profile of energy deposit in absorber 2 (MeV/event)
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...etc...........
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histo 21 : energy flow (MeV/event)
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histo 22 : lateral energy leak (MeV/event)
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NB. Numbering scheme for histograms:
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layer : from 1 to NbOfLayers (included)
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absorbers : from 1 to NbOfAbsor (included)
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planes : from 1 to NbOfLayers*NbOfAbsor + 1 (included)
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One can control the binning of the histo with the command:
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/analysis/h1/set idAbsor nbin Emin Emax unit
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where unit is the desired energy unit for that histo
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One can control the name of the histograms file with the command:
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/analysis/setFileName name (default hadr05)
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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 hadr05)
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