1. 17 Feb 2010 T.Gogami

2.  Uniform distribution now  x’ and y’ uniform distribution θ and φ uniform distribution more realistic

3.  src/HESPrimaryGeneratorAction.cc  GenParUni  uniform  GenFromFile  from seed file virtual photon brems. moller run/input/sample.in x’, Δx’ y’, Δy’ xp = ( Δx’ * 2 * (rand( )-0.5) + x’ ) yp = ( Δy’ * 2 * (rand( )-0.5) + y’ ) G4UniformRand( ) 0-1 θ, φ input file Current source

4. φ : 0 – π θ : 0 – 15° xp = p x /p z =sinθ ・ cosφ/cosθ xp = p y /p z =sinθ ・ sinφ/cosθ θ = π * G4UniformRand( ) * 15/180 φ = π * G4UniformRand( )

5.  tat a

7.  ta

8.  Ta slightly different distribution

9.  Solid angle ~8 [msr]

10.  is this shape good?? Momentum Solid angle

11.  Summary  Theta vs. Phi uniform distribution in GEANT 4.  HES solid angle  8 [msr] (normal position of collimator).  HKS momentum shape is different from current code.  To do  HKS side simulation (theta phi uniform distribution)  Circuit  JPS