HLab Meeting20068/28

K- beam momentum

pK = 1.5 GeV/c : K1.8 + SKS

Both spin-flip and nonflip states should be produced.

K- + n -> + -

1.5 GeV/c

Beam and Setup

Beamline: K1.8 0.5x106 K-/spill at 1.5 GeV/c (9A) K/ >> 1

Spectrometer: SKS (modified) p ~ 4 MeV (FWHM) ~ 110 msr

Hyperball-J ~ 7% at 1 MeV

-

K1.8

K-

　 SDC3,4: Large-size (2.0mx0.8m), fine cell (1~2cm)

　 SMF: Muon filter to suppress K- ->-

　 SP0: Veto counters to reject K- -> -0To be constructed

Beam hits Drift chambers

Low momentum transfer ～ 0.1[GeV/c] Beam K- 1.5[GeV/c] Scattered particle π- ～ 1.4[GeV/c]

Beam rate ～ 500k/spill (700kHz)→580 kHz/wire @ DC sell size 20mm (w/Beam distribution 　 σx=19.8[mm], S=(2π)1/2Aσ)

Beam Scatterer (SBS)

To scatter the beam by Multiple scattering!

Property of SBS

Large radiation length (X0)

Pb :0.56 [cm] →1.77°→ 92kHz W :0.35[cm] → 2.28°→ 72kHz Pt :0.31[cm] → 2.45°→ 64kHz(1.5GeV/c K-, 5cm thickness, 200cm flight path)

Simulation

Straight beam K- 1.5[GeV/c]DC Cell size 20[mm]SBS 5[cm]

DC rate

Simulation: 700kHz→98kHz→76kHz(Calculation: 700kHz→92kHz→72kHz)・ w/o particle decay, Hadronic interaction

Position dependency

Distribution: Gaussian200cm→300cm

DC rate

Decreasing ～１ 8(0.82), 15(0.85), 11(0.89)%

Thickness 50mm→100mm

Decreasing ～ 29(0.71), 28(0.72)% ⇔ 0.71

目標 50kHz/wire @ cell size 20mm(Pb 5cm, Flight path 200cm → 92kHz)(W 5cm, Flight path 200cm → 72kHz) This value is consistent with simulation (98, 76kHz).

W/o particle decay (0.67), Hadronic interaction, Beam distribution

→Decrease DC rate

Simulation Plan

Beam distribution (u=dx/dz, v=dydz) π- contamination (pi/K=0.2) Hadronic interaction→To confirm DC rate

Background study

値段SBS 5cmX5cmX5cm Pb : ～ 0 円 ( その辺のブロック ) W : 10 ～ 20 万円 Pt : 4500 円 /g (d=21.1g/cm3) Rate Pb=1 → W=0.78, Pt=0.72