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SKS Minus Detectors in detail

SKS Minus Detectors in detail. Tohoku Univ. K.Shirotori. Outline. Requirement on setup Setup, SKS & Hyperball-J Detectors in detail, SKS & Veto counters Summary. Proposed “DAY-1” experiment E13.

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SKS Minus Detectors in detail

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  1. SKS Minus Detectors in detail Tohoku Univ. K.Shirotori

  2. Outline • Requirement on setup • Setup, SKS & Hyperball-J • Detectors in detail, SKS & Veto counters • Summary

  3. Proposed “DAY-1” experimentE13 • Several light hypernulcear experiments are submitted (4ΛHe, 7ΛLi, 10ΛB, 11ΛB, 19ΛF). • (K-, π- γ) at pK = 1.5 GeV/c (500k/spill) (Out going π-～1.4 GeV/c) • Experimental setup is determined by these requirements.

  4. Requirement on hypernuclear gamma-ray spectroscopy • To analyze 1.4GeV/c scattered π- by existent spectrometer system. • Large acceptance ～100[msr]. →Enough hypernuclear production yield. • Good momentum resolution 2～4[MeV/c]. →To distinguish excited states of hypernuclear. • (Low background experimental condition) SKS (Superconducting Kaon Spectrometer )

  5. The K1.8 Beam line and SKS Beam spectrometers ・BH1,2 : Time-of-flight ・BAC : π- veto (n=1.03) SMF SKS SKS 2.7T ・SAC : K- veto (n=1.03) ・SFV : K- beam veto ・STOF : Time-of-flight SP0 DC : Beam position measurement Background Veto Target : ～20 g/cm2 ・SMF : μ- from K-→μ-+ν ・SP0 : π- from K-→π-+π0 Beam spectrometer Hyperball-J : γray

  6. K1.8 Beam Line -side view- BDC1,2 BDC3,4 SDC1,2 BDC3,4 BH1 BH2 SFV TOF SMF BAC SAC SP0 SKS part Beam line part Ge+PWO Hyperball-J

  7. SKS Minus • Time-of-flight : STOF • Position measurement : SDC1～4 • Beam veto : SAC • Beam veto : SFV • Veto counter, μ- from K-→μ-+ν : SMF • Veto counter, π- from K-→π-+π0 : SP0 2m

  8. SKS Minus • Time-of-flight : STOF • Position measurement : SDC1～4 • Beam veto : SAC • Beam veto : SFV • Veto counter, μ- from K-→μ-+ν : SMF • Veto counter, π- from K-→π-+π0 : SP0

  9. SKS Minus –Drift chamber- DC active area (num of layer) • SDC1 (4): 350x150[mm] • SDC2 (6): 600x200[mm] →Covering full range, 0～25° →Newly construction (present SDC1 240x150, SDC2 400x150) • SDC3 (6): 2140x1140[mm] • SDC4 (6): 2140x1140[mm] →Shipped form BNL D6 line and added two layers • Resolution ～ 400[μm] • Counting rate /wire < 100kHz • Channel ～3000 2m

  10. SKS Acceptance & Momentum resolution • Acceptance ～120[msr] 100[msr] for present SKS • Momentum resolution 2.1[MeV/c](bending angle ～60° w/ multiple scattering) 0.8[MeV/c] for present SKS (ΔP/P=6.3x10-4) Simulation is checked by present SKS data

  11. SKS Minus –TOF & Beam veto- • TOF : 2240x1000[mm] →32 segments 70x1000x20[mm], 17 new scintillation counters (present 15) →ΔT=200[ps] • SFV : 150x25[mm] →Air light guide • SAC : 200x30[mm] →n=1.03 • SBS : 150x25x50[mm] →Pb, W (300kHz→60kHz/wire) 2m

  12. Time resolution • Flight time ～16[ns] • Path length ～4.63[m] • Momentum Pk=1.5 GeV/c (ΔP/P=1.4x10-4) Pπ form (K, π) reaction (ΔP/P=6.3x10-4) • Present TOF → 300[ps] w/o PHC • Present BH1,2 → 200[ps] w/ PHC

  13. Beam Veto • SAC efficiency ～99% →5k trigger /spill @ 500k/spill SFV →～10 trigger Reduction of acceptance 7.5% • Beam size σx=19.8[mm] σy=3.2[mm] (u=0.02, v=0.002) • SBS K- beam directly hit SDC3,4. ↓ Scattering beam particles by some material (Pb, W) 300kHz→60kHz@ 20mm cell SBS

  14. Target 20cm Background events BAC SAC μ Beam K Decay ν Beam K- decay products make serious background • K-→μ-ν (63.4%) ⇒Muon Filter • K-→π-π0 (21.1%) ⇒PiZero Veto Fake trigger ～1700/spill True event trigger ～700/spill K-→π-π-π+ (5.58%) K-→e-π0ν (4.87%) K-→μ-π0ν (3.27%) K-→π-π0π0 (1.73%) Contribution is relatively small ～150 trigger

  15. 3-body Decay K-→π-π-π+ (5.58%) K-→e-π0ν (4.87%) K-→μ-π0ν (3.27%) K-→π-π0π0 (1.73%)

  16. SKS Minus –Background veto- • SMF : 2200x1400[mm] →11 segments 200x1400x20[mm], Any scintillation counters are OK • Iron : 500x500x500[mm]x12 • +additional parts • SP0 : 1400x1400[mm] →many conuters ～60 • Lead plate : 1400x1400x20(15)[mm]x2～3 2m

  17. Muon Filter Thick Material (ex. Iron) μ- Pass through π- Stopped by hadronic interaction Scintillation counter Scintillation counter Only μ-can be detected.

  18. Muon Filter Before • 89% of μ can be detected in the trigger • In the offline analysis ～100% • Over kill for true π ～1.7% After

  19. PiZero Veto Before • 70% of π0 can be detected by 2 set of 2[cm] lead plate and scintillation counter layer. (75% of γ from π0 hit the SP0) After Simulation in progress

  20. PiZero Veto Beam K Before • 70% of π0 can be detected by 2 set of 2[cm] lead plate and scintillation counter layer. (75% of γ from π0 hit the SP0) After Simulation in progress

  21. Trigger rate (K-, π- γ) at pK = 1.5 GeV/c (500k/spill) • (K-,π-) Reaction rate ～700/spill • K-→μ-ν ～1320/spill • K-→π-π0～390/spill • K- Beam ～10/spill • 3-body decay ～150/spill ～2570/spill w/o Veto counters True trigger ～350/spill w/ Ge trigger and fake trigger greatly decreased. ～1120/spill w/ Veto counters • (K-,π-) Reaction rate ～700/spill • K-→μ-ν ～140/spill • K-→π-π0～120/spill • K- Beam ～10/spill • 3-body decay ～150/spill ～500/spill w/ Ge trigger Comparable to the present trigger rate

  22. Summary • Hypernuclear gamma-ray spectroscopy is feasible with SKS. • Simulations in progress show a good veto counter efficiency. • Estimation of background from heavy counter materials is necessary.

  23. Back up

  24. Beam Momentum K- + n-> L + p-

  25. Level scheme of 7ΛLi

  26. Calculated cross section for 7ΛLi

  27. Iron thickness

  28. Muon Filter

  29. Percentage of decay in target 20cm

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