Gabriele Cosmo
112 lines
3.9 KiB
Plaintext
112 lines
3.9 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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monopole
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--------
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V.Ivanchenko, M.Vladymyrov
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CERN, Geneva, Switzerland
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Lebedev Physical Institute, Moscow, Russia
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This example is devoted to the energy deposited by classical magnetic
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monopole.
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1- GEOMETRY DEFINITION
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The geometry consists of a single block of a homogenous material,
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placed in a world.
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Four parameters define the geometry :
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- the material of the box
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- the thickness of the box
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- the tranverse dimension of the box
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- the maximal step size in target
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The default is 10 cm of alumunium, step is limited by 5mm.
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Equivalent UI commands are following:
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/testex/det/setMat G4_Al
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/testex/det/sizeX 10 cm
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/testex/det/sizeYZ 5 cm
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/testex/det/setStepSize 5 mm
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The default geometry is constructed in DetectorConstruction class,
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but all of the above parameters can be changed interactively via
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the commands defined in the DetectorMessenger class.
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In addition, a global, uniform, and transverse magnetic field can be applied
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via G4MonopoleFieldSetup class, with the default z-value 0.2 tesla.
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This value can be changed via UI command:
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/testex/fld/setField 0.2 tesla
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2- PHYSICS LIST
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The physics list includes standard FTFP_BERT physics and the additional builder
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or monopole physics.
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To define monopole parameters an extra string should be provided via
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the program arguments:
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./monopole -s '2 0 200 GeV' # in the interactive mode
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./monopole -m file.mac -s '2 0 200 GeV' # in the batch mode
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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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block 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 ParticleGun class (see
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the macros provided with this example).
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The default is monopole 100 GeV.
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4- VISUALIZATION
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The Visualization Manager is set in the main() for interactive session,
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the initial parameters of the program are defined in the init_vis.mac macro
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which then executes the visualisation macro, vis.mac.
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The detector has a default view which is a longitudinal view of the box.
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The tracks are drawn at the end of event, and erased at the end of run.
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5- HOW TO RUN ?
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This example handles the program arguments in a similar way as the basic
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B4 example.
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It can be run with the following optional arguments:
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% ./monopole [-m macro ] [-s setupMonopole] [-t nThreads]
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The -s option was already explained in the Physics list section.
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The -t option is available only in multi-threading mode
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and it allows the user to override the Geant4 default number of
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threads. The number of threads can be also set via G4FORCENUMBEROFTHREADS
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environment variable which has the top priority.
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- Execute program in the 'batch' mode from macro files
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% ./monopole -m monopole.in [-s setupMonopole]
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- Execute program in the 'interactive mode' with visualization
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% ./monopole [-s setupMonopole]
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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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6- HISTOGRAMS
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The result is five histograms:
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- Monopole eneregy deposition in current material
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- dedx for proton
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- dedx for monopole
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- range for proton in current material
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- range for monopole in current material
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The histogram is saved in Root file.
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Limit of bin size can be set with testex/run/binSize (default 5mm). Real size
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is chosen as a minimal between this and step limit (see Geometry section)
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