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HES Simulation LogHES Simulation LogNov ’06 Part2Nov ’06 Part2

HES Simulation LogHES Simulation LogNov ’06 Part2Nov ’06 Part2

1.VP Fluxについて

2.HES Acceptance

3.HES Tracking

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About VP FluxAbout VP Flux

(e,e’K+) reaction

The definition of VP Flux (Γ)

(e,e’K+) diff. Cross SectionΩ, ω : Angle and Momentum of e’

VP absorption Cross Section

要するにどれだけの数の vp を生成したか、という量

T.DEForest, Jr and J.D.Walecka, ”Electron Scattering and Nuclear Structure”,

Advances In Physics 15 (1966) 1.

Γ Formula

Reference:

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VP Flux and its integrationVP Flux and its integrationTotal VP Yield → Integration of Γ(Ω,ω)

represent the Acceptance of Spectrometer

Independent on the target and beam intensity (Integrated) VP Flux (unit : [NoVP/NoE])

NoVP : Number of Virtual PhotonNoE : Number of Electron

Ntotal → depend on the target and beam intensity VP Rate [NoVP/sec]

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VP Flux @ E01-011VP Flux @ E01-011

Assumption : 100mg/cm2 12C target, 20uA beam, σγ=100 [nb/sr] HKS Solid Angle = 0.015 [rad] , Kaon Decay Rate = 0.3

VP Flux[NoVP/NoE]

VP Rate[NoVP/sec/sr]

12ΛB g.s Ratio

[g.s./hr]Rough Estimation ～ 0.20×10-4 ～ 1.2 ～ 19

Geant3 Simulation 0.35×10-5 0.22 3.6

Measured Value - - 7-8 ?

Conditions on Rough Estimation : -120<x’<120[mrad], 70<y’<90[mrad], 　　　　　　　 p=300[MeV], dp=±30%

inconsistent

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VP Flux @ E05-115 (HES)VP Flux @ E05-115 (HES)

Assumption : 100mg/cm2 12C target, 20uA beam, σγ=100 [nb/sr] HKS Solid Angle = 0.008 [rad] , Kaon Decay Rate = 0.3

VP Flux[NoVP/NoE]

VP Rate[NoVP/sec/sr]

12ΛB g.s Ratio

[g.s./hr]Geant4 Simulation

1.1×10-4 6.8 59

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HESHESのの AcceptanceAcceptance そのその 11

メインの領域で大体 8msrは確保できていると思われる

Tilt : 7.3deg, Central Mom: 967MeV

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HESHESのの AcceptanceAcceptance そのその 22

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HES Tracking for Detector HES Tracking for Detector SizeSize

[cm]

Distance from D Magnet [cm]

magenta: abs(δ)<5%, blue: 5%<abs(δ)<10%green: 10%<abs(δ)<15%, red: 15%<abs(δ)

*Plot is not only for mid plane, but for all available y value

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収束の様子収束の様子p=0.967[GeV/c]

1.15p

p

0.85p

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Splitter PoleSplitter Pole の効果の効果

赤： SPL Poleにぶつからなかった粒子。数にして 5%くらい減っている。