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Upgrade of PID for BESIII

Upgrade of PID for BESIII. June 13, 2006 Institute of High Energy Physics, Beijing, China Yuekun Heng ( hengyk@mail.ihep.ac.cn ). Outline. Present TOF design Physics requirements for PID Upgrade to MRPC ?? Upgrade to Internally reflecting Cherenkov detector: CCT, TOP, Focusing DIRC

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Upgrade of PID for BESIII

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  1. Upgrade of PID for BESIII June 13, 2006 Institute of High Energy Physics, Beijing, China Yuekun Heng (hengyk@mail.ihep.ac.cn)

  2. Outline • Present TOF design • Physics requirements for PID • Upgrade to MRPC?? • Upgrade to Internally reflecting Cherenkov detector:CCT, TOP, Focusing DIRC • Summary and discussion

  3. 1. Present TOF Design

  4. Present barrel TOF The option of barrel TOF is determined after many discussions in June, 2005. Two layers of scintillator will be used for barrel. CsI Calorimeter Barrel TOF Drift Chamber Endcap TOF

  5. Barrel TOF alignment Fig. BTOF side view. To save space, the base of PMT housing is 6-sides-shaped and the inner and outer layer is across. It has four screws to connect the scin. Fig. Assembly of barrel TOF.

  6. Endcap TOF structure

  7. Analysis of Time reso. Non TOF ~60ps

  8. Why two layers? • Time reso. For Kaon and pion is worse 20% than muon in experiences. • Time reso. Of two layers totally is from 100ps to 110ps for kaon and pion. • That time reso. Can separate kaon/pion of 0.9GeV in the middle of barrel. Capability of separation of Kaon and Pion

  9. 2. Physics targets for PIDand our space limits

  10. K/πmomentum on BESIII • BEPCII: 2.0~4.2GeV • BESIII: • Charm physics:J/Psi, Psi’, Psi’’ • Tau Physics • K/π momentum: almost all<1.5GeV • K/π seperation: 1.2GeV is enough • Present TOF: 0.9GeV(2sigma,95%) Momentum distribution for hadrons at J/psi Next target

  11. Experimental Searching forD0D0 Mixing (From He Kanglin ) • Big challenge to PID (Kπchannel) • Main backgrounds come from the double miss-PID • Searching in semi-leptonic decay modes are experimental difficulty with 2 missing neutrino (hard to reduce background contribution to 10-4) • Monte Carlo study with different PID (TOF resolution)

  12. Detection efficiency vs TOF resolution

  13. Background rates vsTOF resolution

  14. PID space limits • Banded to MDC outer barrel of Carbon-fiber • R-direction space: 81cm-92.5cm • Scintillator Length: 2320mm • Coverage:~82% PID space

  15. 3. Upgrade to MRPC??

  16. Target analysis for MRPC • To get 1.2GeV separation of K/pi, totally time reso. <80ps • Non-TOF is 60ps, TOF <60ps,Plastic scin. Can’t give so good time.MRPC may be OK. • To cover dead area of MRPC, overlap of two layers of MRPC is needed. • To reduced electronics, MRPC should be long strip and readout by two ends. • Long-strip MRPC needs much more studies.

  17. MRPC results

  18. III. 4 gaps, 0.3mm/gap HV:10kV/mm Preamp: not say GAS: 85% C2H2F45% iso- C4H10 10%SF6， 达到的时间分辨为75ps

  19. MRPC optionbakelite as the resis. plate • Structure: • Resi. Plate: bakelite • gaps: 6; • Chamber: 8cm(W)X190cm(L) • gas：90%Freon, 5%iso-butane, • 5%SF6 • Preamp：Star • Signal pulse • HV: 16kV/1.2mm) • Readoud pad:3X6cm • Rise time:~2ns • Time Reso.:70～110ps The results for a MRPC sample where the fish-line is rolled in longitude direction

  20. Our tests 钓鱼线竖绕板室

  21. 钓鱼线竖绕板室的初步实验结果（吴金杰） • Structure: • Resi. Plate: bakelite • gaps: 6; • Chamber: 8cm(W)X190cm(L) • gas：90%Freon, 5%iso-butane, • 5%SF6 • Preamp：Star • Signal pulse • HV: 16kV/1.2mm) • Readoud pad:3X6cm • Rise time:~2ns • Time Reso.:~110ps Reasons: gap not well

  22. 钓鱼线横绕的MRPC实验结果（安正华） 两边气槽和边框共占去3cm，有效面积约65％。

  23. MRPC signal

  24. T-Q correction

  25. 14.5kV MRPC: Time reso. 上图是MRPC幅度谱在100－400的时间分辨 由此可计算出MRPC的本征时间分辨 sqrt(3.907*3.907-2.837*2.837)*25ps=67.16ps

  26. 14.5kV MRPC 实验总结 时间分辨 上图是MRPC幅度谱在401－2047的时间分辨 由此可计算出MRPC的本征时间分辨 sqrt(6.709*6.709-2.926*2.926)*25ps=150.93ps

  27. 4. Internally reflecting Cherenkov detector:CCT, TOP, Focusing DIRC

  28. Cherenkov detectors

  29. Internally reflecting cherenkov detector • Using internally reflecting cherenkov light • Parameters to know: • track direction • Cherenkov light(x,y), or (theta, phi) • Transmitting time:

  30. 3 options (refers to Honscheid ,Ohshima,Vavra,) CCT(Cherenkov Correlated Timing ) • 1D Timing only • a) Time is related to cherenkov angle

  31. CCT • Its principle is to measure the time of the cerenkov light to separate particles. • We did simulations. There are about 10 PEs for 2inches PMT with QE of 20%. reso. • Transit time spread of PMT: • Line-focus type PMT, 250ps (xp2020) • Fine-mesh type PMT, 180ps (R5924) • Micro-Channel-Plate type PMT, 50ps (R2809U)

  32. Potential of CCT: MCP-PMT to give good time reso. Refer to:Jochen Schwiening, SLAC T. Ohshima, Nagoya Univ.

  33. TOF+TOF TOF+CCT Comparison of K/ sep. Fig. K / separation for Double TOF Fig. K / separation for TOF+CCT

  34. TOP: Time of Propagation • Principle: only Φcandθc can determine cherenkov angle. TOP and Φ can deduce them. • Quartz bar’s sides are vertical and conserve the Φc. Quartz lightguide is needed to ensure the light direction out of quartz bar • Fucussing Mirror: fucussing the parrel light because of the thickness of quartz bar. • Photon detector is placed opposite of mirror. • To deduce dead area, the detection end will be placed in opposite ends for adjacent counters

  35. Uncertainties of TOP • Chromatic error. 5‰。 • Uncertainty of Φc. Mirror’s resolution and PMT position resolution, can be 9mrad. • Time spread of PMT • Start time resolution • Thickness of quartz bar. High speed particle transmit quartz bar (20mm) needs about 66ps. But when particle inclined transmits, the uncertainty will be reduced because particle transit time and light transit time lessen it. • Position of injected particle. ~2mm，~10ps • Photon electron number Cherenkov ring by Y.Enari Using TOP. Particle 4GeVπ，position:1m. 2GeVπ，position:0.02m和1m处. TOP resolution VS Φ.By Ohshima.

  36. TOP: Candidate of Super Belle Refer to Peter Krizan, Super B factory workshop, Frascati, 2006

  37. TOP: For BESIII, 1.2 GeV is enough, 1.5 GeV is very good. Refer to Noriaki Sato, 2005, hawaii

  38. Focusing DIRC • Measure the time and 2dimension position • It uses APD or MCP PMT to measure the time and position of Cerenkov light from Quartz. • No big imaging circles and so no much space is needed. • The money is saved because of smaller quantity of PMT.

  39. Candidate of Babar’s next plan From Vavra, Hawaii workshop

  40. 5. Summary • 1.2GeV K/Pi separation is needed for BESIII physics. Now it is only 0.9GeV. Upgrade is nessesary. • <60ps of Long-strip MRPC is OK to give 1.2GeV separation. Experiments is under way. 60ps is not easy. • CCT has good potential for the upgrade. It is simple with MCP-PMT of good time reso. • TOP can give over 1.5GeV separation of K/pi. • Focusing DIRC needs more space, impossible for BESIII

  41. The End Thanks a lot!

  42. K/Pi difference of cherekov light

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