Gabriele Cosmo
93 lines
3.7 KiB
Plaintext
93 lines
3.7 KiB
Plaintext
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RE04 - An extended example for run and event
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Contact : M.Asai (SLAC)
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1. Introduction
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This example demonstrates how to define a layered mass
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geometry in parallel world. In the mass (tracking) world,
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there are two boxes only. One is the world volume and the
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other is a box in the world. They both are made of air.
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Thus, if tracks do not see materials (water and lead)
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defined in the parallel world, they rarely interact.
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In the parallel world, there are boxes made of water and
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lead.
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1.1 Geometry
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RE04DetectorConstruction defines the mass (tracking)
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geometry. It firstly defines all materials which apear
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either in mass world or parallel world. Then in SetupGeometry()
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method, it defines the world volume and a box named "phantom".
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Both boxes are made of air.
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RE04ParallelWorldConstruction defines the parallel world.
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For a parallel world, solid, logical and physical volumes
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which represent parallel world must not be created here but
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should be taken through G4VUserParallelWorld::GetWorld()
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method which creates clones of solid, logical and physical
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volumes of the world volume of the mass world. Please note
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that this cloned logical volume of the parallel world volume
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does not have a valid pointer to aa material but null.
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In the parallel world, if a logical volume has a valid
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material pointer, a track in this volume (precisely saying
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a physical volume which is made of this logical volume)
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will see the material defined in this logical volume,
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regardless of the material in the mass geometry. If a
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logical volume has a null material pointer, a track will
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see the ordinary material defined in the mass world.
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RE04ParallelWorldConstruction defines one placement
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volume of box-shape, which is made of water, and a mother
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box (placement volume with null material pointer), which
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contains parameterized volumes. RE04ParallelWorldParam
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class defines a parameterization of the parameterized
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volume "paraPara", which represents two boxes at different
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locations and made of water and lead respectively.
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1.2 Physics
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RE04PhysicsList uses ordinary physics builders. It also
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defines G4ParallelWorldProcess which deals with the parallel
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world. This G4ParallelWorldProcess is an extension of
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G4ParallelWorldScoringProcess. If SetLayeredMaterialFlag()
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of this process class is invoked, in addition to taking
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care of sensitive detectors in the parallel world, it also
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takes care of layered mass geometry. If this set method is
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not invoked, it behaves exactly same as G4ParallelWorldScoringProcess.
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The constructor of G4ParallelWorldProcess takes the name
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of the parallel world physical volume as an argument.
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G4ParallelWorldProcess may be associated only to some
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limited kinds of particle types. The parallel world is
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seen only bythe particles which have G4ParallelWorldProcess
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in their process manager objects. In this RE04 example
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G4ParallelWorldProcess is defined to all particle types
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except ChargedGeantino. Thus, if you shoot CargedGeantino,
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it won't see any volume boundary defined in the parallel
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world.
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2. Macro files
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The macro file "score.mac" defines a scoring mesh which covers
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the "Phantom" and scores energy deposition. It shoots 1000
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primary particles (by default 10 GeV muon-). Though the mass
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world has only air, given tracks, both primary muons and
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secondary particles see water and lead defined in the parallel
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world, you will see the energy deposition is not evenly
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distributed.
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3. User action classes
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In the main() of RE04.cc, three user action classes, i.e.
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RE04EventAction, RE04TrackingAction and RE04SteppingAction,
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are commented out. By using RE04SteppingAction, you will
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see a material name which a track sees for each step.
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By using RE04EventAction and RE04TrackingAction, you will
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see the similar information for all trajectories of one
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event.
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