4/27/2010 T.Gogami 花見 4/20/2010

 GEANT4 Simulation  uniform distribution  HES HKS solid angle

 design  magnet  detector  distribution Monte Carlo simulation GEANT4 predict results

define matters EQ1 EQ2 Splitter D Magnet Detectors Target generate events e e e

 Uniform distribution now  x’ and y’ uniform distribution at target spherical uniform distribution more realistic

 src/HESPrimaryGeneratorAction.cc  GenParUni  uniform  GenFromFile  from seed file virtual photon brems. moller G4UniformRand() 0-1 θ, φ Current source

θ : 0 – φ : 0 – π

r=1 [cm] θ : 0 ~ π/2 φ : -π ~ π dense !

φ : 0 – 2π θ : 0 – π/2

r=1 [cm] θ : 0 ~ π/2 φ : -π ~ π

r

input/sample.in θ, Δθ, φ, Δφ θ Δθ min max a Δa

θ = 0.3 ± 0.3 [rad] φ = 0 ± π [rad] θ = 0.5 ± 0.2 [rad] φ = 0 ± π [rad]

θ = 0.4 ± 0.3 [rad] φ = 0.5 ± π/2 [rad] works well

Collimator on 7.5 [msr] 5.0 [msr] HKS HES

 Spherical uniform distribution  Solid Angle with collimator at central momenta  HES ~= 5.0 [msr]  HKS ~= 7.5 [msr] GEANT4 simulation Splitter D Magnet KQ1 KQ2 Detectors HKS 三神峯公園 4/25/2010