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0001
0002 RE04 - An extended example for run and event
0003 --------------------------------------------
0004
0005 Contact : M.Asai (SLAC)
0006
0007 1. Introduction
0008
0009 This example demonstrates how to define a layered mass
0010 geometry in parallel world. In the mass (tracking) world,
0011 there are two boxes only. One is the world volume and the
0012 other is a box in the world. They both are made of air.
0013 Thus, if tracks do not see materials (water and lead)
0014 defined in the parallel world, they rarely interact.
0015 In the parallel world, there are boxes made of water and
0016 lead.
0017
0018 1.1 Geometry
0019
0020 RE04DetectorConstruction defines the mass (tracking)
0021 geometry. It firstly defines all materials which apear
0022 either in mass world or parallel world. Then in SetupGeometry()
0023 method, it defines the world volume and a box named "phantom".
0024 Both boxes are made of air.
0025
0026 RE04ParallelWorldConstruction defines the parallel world.
0027 For a parallel world, solid, logical and physical volumes
0028 which represent parallel world must not be created here but
0029 should be taken through G4VUserParallelWorld::GetWorld()
0030 method which creates clones of solid, logical and physical
0031 volumes of the world volume of the mass world. Please note
0032 that this cloned logical volume of the parallel world volume
0033 does not have a valid pointer to aa material but null.
0034
0035 In the parallel world, if a logical volume has a valid
0036 material pointer, a track in this volume (precisely saying
0037 a physical volume which is made of this logical volume)
0038 will see the material defined in this logical volume,
0039 regardless of the material in the mass geometry. If a
0040 logical volume has a null material pointer, a track will
0041 see the ordinary material defined in the mass world.
0042
0043 RE04ParallelWorldConstruction defines one placement
0044 volume of box-shape, which is made of water, and a mother
0045 box (placement volume with null material pointer), which
0046 contains parameterized volumes. RE04ParallelWorldParam
0047 class defines a parameterization of the parameterized
0048 volume "paraPara", which represents two boxes at different
0049 locations and made of water and lead respectively.
0050
0051 1.2 Physics
0052
0053 RE04PhysicsList uses ordinary physics builders. It also
0054 defines G4ParallelWorldProcess which deals with the parallel
0055 world. This G4ParallelWorldProcess is an extension of
0056 G4ParallelWorldScoringProcess. If SetLayeredMaterialFlag()
0057 of this process class is invoked, in addition to taking
0058 care of sensitive detectors in the parallel world, it also
0059 takes care of layered mass geometry. If this set method is
0060 not invoked, it behaves exactly same as G4ParallelWorldScoringProcess.
0061 The constructor of G4ParallelWorldProcess takes the name
0062 of the parallel world physical volume as an argument.
0063
0064 G4ParallelWorldProcess may be associated only to some
0065 limited kinds of particle types. The parallel world is
0066 seen only bythe particles which have G4ParallelWorldProcess
0067 in their process manager objects. In this RE04 example
0068 G4ParallelWorldProcess is defined to all particle types
0069 except ChargedGeantino. Thus, if you shoot CargedGeantino,
0070 it won't see any volume boundary defined in the parallel
0071 world.
0072
0073 2. Macro files
0074
0075 The macro file "score.mac" defines a scoring mesh which covers
0076 the "Phantom" and scores energy deposition. It shoots 1000
0077 primary particles (by default 10 GeV muon-). Though the mass
0078 world has only air, given tracks, both primary muons and
0079 secondary particles see water and lead defined in the parallel
0080 world, you will see the energy deposition is not evenly
0081 distributed.
0082
0083 3. User action classes
0084
0085 In the main() of RE04.cc, three user action classes, i.e.
0086 RE04EventAction, RE04TrackingAction and RE04SteppingAction,
0087 are commented out. By using RE04SteppingAction, you will
0088 see a material name which a track sees for each step.
0089 By using RE04EventAction and RE04TrackingAction, you will
0090 see the similar information for all trajectories of one
0091 event.
0092
