Gabriele Cosmo
154 lines
5.6 KiB
Plaintext
154 lines
5.6 KiB
Plaintext
$Id: README 93736 2015-10-30 11:01:12Z gcosmo $
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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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TestEm2
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-------
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How to do shower profiles in an homogenous medium, with virtual
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voxelisation.
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1- GEOMETRY DEFINITION
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The geometry consists of a cylinder of homogenous material.
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The default geometry is constructed in DetectorConstruction class,
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but all of the above parameters can be modified interactively via
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the commands defined in the DetectorMessenger class.
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Material can be choosen: Air Water lAr Al Fe BGO PbWO4 Pb.
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eg: /testem/det/setMat PbWO4
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The cylinder is virtually sliced longitudinally (slice) and radially
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(ring). The size of the slices and rings are expressed in radiation
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length units and can be changed.
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eg: /testem/det/setLbin 20 1. ---> 20 slices of 1. radl
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/testem/det/setRbin 5 0.25 ---> 5 rings of 0.25 radl
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/testem/det/update ---> rebuild the geometry
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(MaxBin = 500 in both directions)
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An uniform magnetic field along the cylinder axis can be set.
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eg: /globalField/setValue 0 0 5 tesla
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2- PHYSICS LISTS
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Physics lists are based on modular design. Several modules are instantiated:
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1. Transportation
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2. EM physics
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3. Decays
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4. StepMax - for step limitation
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EM physics builders can be local (eg. in this example) or from G4 kernel
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physics_lists subdirectory.
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Local physics builders:
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- "local" standard EM physics with current 'best' options setting.
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these options are explicited in PhysListEmStandard
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From geant4/source/physics_lists/builders:
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- "emstandard_opt0" recommended standard EM physics for LHC
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- "emstandard_opt1" best CPU performance standard physics for LHC
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- "emstandard_opt2" similar fast simulation
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- "emstandard_opt3" best standard EM options - analog to "local" above
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- "emstandard_opt4" best current advanced EM options standard + lowenergy
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- "emstandardWVI" standard EM physics and WentzelVI multiple scattering
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- "emstandardSS" standard EM physics and single scattering model
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- "emlivermore" low-energy EM physics using Livermore data
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- "empenelope" low-energy EM physics implementing Penelope models
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- "emlowenergy" low-energy EM physics implementing experimental
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low-energy models
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Physics lists and options can be (re)set with UI commands
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Please, notice that options set through G4EmProcessOptions are global, eg
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for all particle types. In G4 builders, it is shown how to set options per
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particle type.
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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
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cylinder perpendicular to the input face. The type of the particle
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and its energy are set in the PrimaryGeneratorAction class, and can
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changed via the G4 build-in commands of G4ParticleGun class (see
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the macros provided with this example).
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A RUN is a set of events.
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4- VISUALIZATION
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The Visualization Manager is set in the main() (see TestEm2.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 detector has a default view which is a longitudinal view of the
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cylinder.
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The tracks are drawn at the end of event, and erased at the end of run.
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Optionally one can choose to draw all particles, only the charged one,
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or none. This command is defined in EventActionMessenger class.
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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 build-in interactive command (/process/inactivate procname)
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allows to activate/inactivate the processes one by one.
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The threshold for producing secondaries can be changed.
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eg: /testem/phys/setCuts 100 microm
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/run/initialize
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The shower profiles are histogramed, if histograming is activated.
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They can be also printed with the command /testem/run/verbose 1
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6- HOW TO START ?
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- Execute TestEm2 in 'batch' mode from macro files
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% TestEm2 run01.mac
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- Execute TestEm2 in 'batch' mode using multi-threading
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% TestEm2 run01.mac 4
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here 4 is number of threads, it should be user defined,
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optimal value depends on hardware
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- Execute TestEm2 in 'interactive mode' with visualization
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% TestEm2
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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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7- HISTOGRAMS
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TestEm2 produces several histograms:
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Content of these histo:
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1 : energy deposit per event
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2 : charged track length per event
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3 : neutral track length per event
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4 : longitudinal energy profile
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5 : rms of longitudinal energy profile
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6 : cumulated longitudinal energy profile
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7 : rms of cumulated longitudinal energy profile
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8 : radial energy profile
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9 : rms of radial energy profile
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10 : cumulated radial energy profile
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11 : rms of cumulated radial energy profile
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To define the output file name with histograms, use the UI command :
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"/testem/histo/setFileName name"
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The format of the histogram file can be : root (default),
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xml, csv, by selecting g4nnn.hh in RunAction.hh
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