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Status of BESIII and upgrade of BESIII

Status of BESIII and upgrade of BESIII. Ming Shao / USTC for the BES Collaboration. Outline. Commissioning of BEPCII/BESIII Performance of the BESIII detector Upgrade of BESIII Summary. BEPC II Storage ring : Large angle, double-ring. RF. SR. RF. Beam energy: 1.0-2.3GeV

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Status of BESIII and upgrade of BESIII

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  1. Status of BESIII and upgrade of BESIII Ming Shao / USTC for the BES Collaboration

  2. Outline • Commissioning of BEPCII/BESIII • Performance of the BESIII detector • Upgrade of BESIII • Summary

  3. BEPC II Storage ring: Large angle, double-ring RF SR RF Beam energy: 1.0-2.3GeV Luminosity: 1×1033 cm-2s-1 Optimum energy: 1.89 GeV Energy spread: 5.16 ×10-4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A SR mode: 0.25A @ 2.5 GeV IP

  4. Main parameters achieved in collision mode

  5. BESIII detector SC magnet,1T Magnet yoke RPC MUC TOF, (barrel) 90/ (endcap)110~120ps Be beam pipe MDC, 130 mm CsI(Tl) calorimeter, 2.5%@1GeV

  6. First collision event on July 19, 2008 14 M y’ events collected in 2008

  7. Drift chamber • To measure the momentum of charged particles by their curvature in the magnetic field • 7000 Signal wires: 25 mm gold-plated tungsten • 22000 Field wires: 110 mm Al • Gas: He + C3H8 (60/40) • Momentum resolution@1GeV: Babar: ~110mm BELLE: ~130mm CLEO: ~110mm BESIII: ~130mm

  8. ●Layer 7 ●Layer 22 MDC calibration Reso. 136 mm Eff.: ~ 98% Beam related backgrounds σP=13.7MeV/c Wire reso.

  9. dE/dx resolution dE/dxreso.: 5.80% p K 

  10. BESIII CsI(Tl) crystal calorimeter Babar: 2.67%@1GeV BELLE: 2.2% @1GeV CLEO: 2.2% @1GeV BESIII: 2.5%@1GeV • To measure the energy of electromagnetic particles • Barrel: 5280 crystals，Endcap: 960 crystals • Crystal: (5.2x 5.2 – 6.4 x 6.4) x 28cm3 • Readout: 13000 Photodiodes, 1cm2cm, • Energy range：20MeV – 2 GeV • position resolution: 6 mm @ 1GeV • Tilt angle: theta ~ 1-3o, phi ~ 1.5o

  11. EMC calibration Barrel energy resolution • energy deposit for e+e-gg Position resolution for Bhabha energy resolution for Bhabha events 4.4 mm

  12. PID: TOF system • Barrel: 2*88 BC 408, 2.4 m long, 5cm thick • Endcap：2*48 BC 404 • PMT: Hamamatzu R5924

  13. TOF calibration TOF Barrel:103ps Design：100~110ps (single layer) Endcap TOF：125ps Design：110~120ps

  14. m system : RPC • 9 layer, 2000 m2 • Special bakelite plate w/o lineseed oil • 4cm strips, 10000 channels • Noise less than 0.1 Hz/cm2

  15. MUON Chamber Efficiency Spatial resolution Single counting rate

  16. BESIII commissioning and data taking milestones Mar. 2008: first full cosmic-ray event April 30, 2008: Move the BESIII to IP July 20, 2008: First e+e- collision event in BESIII Nov. 2008: ~ 14M (2S) events collected April 14, 2009 ~100M (2S) events collected May 30, 2009 ~42 pb-1 at continuum collected (3.65 GeV) July 28, 2009 ~200M J/ events collected Peak Lumi. @ Nov. 2008: 1.21032cm-2s-1 Peak Lumi. @ May 2009: 3.21032cm-2s-1

  17. Data accumulated at BESIII Mar. 6 – April 14 May 24 – June 2 100 M (2S) data 42 pb-1 data at 3.65 GeV June 12 – Jul. 28 200 M J/ data

  18. Upgrade of BESIII TOF ! ΔT>3.38 σ separation rate >95.4%(2σ) ΔT>5.60 σ separation rate >99.7%(3σ) Current time resolution can separate kaon/pion of <0.95GeV/c in the middle of barrel We aim at 1.1-1.2GeV/c

  19. Time resolution in BESIII/TOF Non TOF ~60ps Target:Intrinsic time resolution < 45 ps, Total time resolution < 72 ps, corresponding to a K/pi separation capability up to >1.1 GeV (95%C.L.). Upgrade!

  20. TOF Technique - MRPC A 24 gaps Timing MRPC

  21. Beam Test at T10 Efficiency (%) Time resolution(ps) HV (kV) HV (kV) Signal width – TOT (ns) Time distribution (ps)

  22. Schematic view of MRPC TOF endcap barrel

  23. Summary • BEPCII achieved a luminosity of 31032cm-2s-1 • The performance of the BESIII detector reached expectations • 100 M y’ , 200M J/ events have been accumulated; the data quality is good & preliminary results are being obtained • We are expecting exciting physics results • Upgrade of BESIII is undergoing Thank you !

  24. EMC installation

  25. MDC and TOF installation

  26. Be Beam-pipe installation

  27. BESIII moved to IP: precision < 1 mm

  28. MDC Data/MC comparison • Detailed simulation: • Resolution/efficiency of each cell as a function of drift distance, DOCA, Q, HV, Noise, entrance angle, … • Improvements: more data, better understanding, …

  29. Very low electronics noise (EMC)

  30. EMC Data/MC comparison for Bhabha events Dots: data Solid line: MC with background mixing Dash line/shade: MC without background mixing

  31. EMC Data/MC comparison e- e+ p- p+ p

  32. Summary of BESIII performance ●Layer 7 ●Layer 22 Wire reso. Design: 130 mm dE/dxreso.: 5.80% Design：6-8% CsI(Tl) energy reso. Design: 2.5%@ 1 GeV Barrel TOF reso.: 78ps Design：90ps Bhabha

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