$Id: README 78303 2013-12-11 10:50:38Z gcosmo $
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     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                            PicoVeto
                            --------

This example presently illustrates the following basic concepts, and in
particular (indicated with ***), how to use G4 for optical photon
generation and transport. Other extended example of what is possible
in Geant4 with optical photons can be found at
examples/extended/optical/LXe and wls.

main()
------

 ==> define Random Number Engine and initial seed

G4VUserPhysicsList
------------------

 ==> define particles; including *** G4OpticalPhoton     ***
     define processes; including *** G4Cerenkov          ***
                                 *** G4Scintillation     ***
                                 *** G4OpAbsorption      ***
                                 *** G4OpRayleigh        ***
                                 *** G4OpBoundaryProcess ***

G4VUserDetectorConstruction
---------------------------

 ==> define material: Air and Water
     define simple G4box geometry
     *** add G4MaterialPropertiesTable to G4Material       ***
     *** define G4LogicalSurface(s)                        ***
     *** define G4OpticalSurface                           ***
     *** add G4MaterialPropertiesTable to G4OpticalSurface ***

G4VUserPrimaryGeneratorAction
-----------------------------

 ==> Use G4ParticleGun to shoot a charge particle into a Cerenkov radiator
 
 ==> A messenger command allows to define interactivly the polarization of an
     primary optical photon (see for instance optPhoton.mac)
 
G4UserRunAction
---------------

==> define G4Timer (start/stop)
    set verbose levels

G4UserStackingAction
--------------------

==> show how to count the number of secondary particles in an event

Visualisation
-------------
 
 The Visualization Manager is set in the main().
 The initialisation of the drawing is done via a set of /vis/ commands
 in the macro vis.mac. This macro is automatically read from
 the main in case of interactive running mode.
 
 The detector has a default view which is a longitudinal view of the tank.
 The tracks are drawn at the end of event, and erased at the end of run.
 
 HOW TO START
 ------------
 
 - compile and link to generate an executable
 	% cd PicoVeto
 	% gmake

   This example handles the program arguments in a new way.
   It can be run with the following optional arguments:
   % PicoVeto [-m macro ] [-u UIsession] [-t nThreads]

   The -t option is available only in multi-threading mode
   and it allows the user to override the Geant4 default number of
   threads. The number of threads can be also set via G4FORCENUMBEROFTHREADS
   environment variable which has the top priority.

 - execute PicoVeto in 'batch' mode from macro files
 	% PicoVeto -m PicoVeto.in
 
 - execute PicoVeto in 'interactive mode' with visualization
 	% PicoVeto
 	....
 	Idle> type your commands. For instance:
 	Idle> /control/execute optPhoton.mac
 	....
 	Idle> exit