RE01 - An extended example for run and event
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 Contact : M.Asai (SLAC) 

1. Introduction

 This example demonstrates how to connect the information between
primary particles and hits. It also utilize some user-information
classes.

1.1 Geometry and region information

 It has a quite simple sylindrical tracker of 5 layers and a
sylindrical calorimeter of lead and scintillator. Dedicated regions
are assigned to both tracker and calorimeter mother volumes not
for setting additional production thresholds but for adding some
more information to these regions. RE01RegionInformation is the
class for this purpose.
 A "readout geometry" is attached to the calorimeter to define
its cells.

1.2 Physics

 This example basically uses LHEP_BERT physics list. In addition 
to this, RE01DecayPhysics is used for adding G4UnknownParticle and
G4UnknownDecay process.

1.3 Event generator

 An event sample is attached. This event has a Higgs particle
which decays into e+e- and mu+mu- pairs through two Z bosons.
It uses G4HEPEvtInterface. 
 In this example, by utilizing G4UnknownParticle, all particles
appear in the primary event are converted to G4Track and then
to RE01Trajectory. Relation between primary particles and track
IDs are shown at the end of event execution.

2. "Source track" information

 "Source track" is meant for a track that is either a primary
particle or a track born is the tracking region. This information
is stored in RE01TrackInformation class object and copied from
a parent track to its daughters.

2.1 Track suspension

 All source tracks are suspended for their tracking when they are
getting into the calorimeter region. Thus, all tracks in the tracker
region are tracked before generating any shower in the calorimeter.

2.2 Tracker hits associated with primary particle information

 Information kept in RE01TrackInformation is used to connect each
tracker hit to the primary particle.

2.3 Energy deposition of each source track

 Utilizing RE01StackingAction, shower generation is done for each
souorce track separately, and thus energy deposition in calorimeter
cells are shown for each individual source track. With the trajectory
information, energy deposition for each primary particle can also
be gotten.