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     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
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                            field06 Example
                            ---------------

     This example exercises the new (in 9.5) capability of tracking massive
     particles in a gravity field.

     Credit goes to Erik Miller (Univ. of Northern British Columbia) and
     Garry Yan (Univ. of Toronto)

**************
*Classes Used*
**************

 1 - main()

 2- GEOMETRY DEFINITION

    as simple world G4Box with a G4UniformGravityField propagating momentum
    (G4EqGravityField) with G4ClassicalRK4(fEquation,8). The example uses the
    default gravity field on the earth's surface: gy = -9.81*m/s/s/c_light.

 3- AN EVENT: THE PRIMARY GENERATOR

    uses an Ultra Cold Neutron (UCN) and G4ParticleGun with:
    particleEnergy = G4UniformRand()*1e-7*eV

    UCN are launched from (0,0,0) uniform into 4pi

 4- PHYSICS

    The simulation knows of only four particles: G4Neutron, G4Proton, 
    G4Electron and G4AntiNeutrinoE

    RegisterPhysics(new G4DecayPhysics());
    RegisterPhysics(new F06ExtraPhysics());

    G4VModularPhysicsList::ConstructProcess();

    AddBetaDecay to "neutron" as an example of how to set a decay-table with
    decay-channel(s) to a G4ParticleDefinition.

    F06ExtraPhysics defines G4StepLimiter and G4UserSpecialCuts

 5- User Action Classes

        EventAction:
            EndOfEventAction - draws trajectories in G4TrajectoryContainer

 6- HOW TO START ?

        - compile and link to generate an executable
                % cd $G4INSTALL/example/extended/field/field06
                % gmake

        - execute field06 in 'batch' mode from macro files e.g.
                % $(G4INSTALL)/bin/$(G4SYSTEM)/field06 field06.in > field06.out &

        - execute field06 in 'interactive' mode with visualization e.g.
                % $(G4INSTALL)/bin/$(G4SYSTEM)/field60
                ....
                Idle> type your commands, for example:
                Idle> run/beamOn 1
                ....