The progress of TOF

1. The progress of TOF June 13, 2006 Institute of High Energy Physics, Beijing, China Yuekun Heng (hengyk@mail.ihep.ac.cn)

2. Outline • TOF design • Alignment & mech. • PMT tests • Beam tests and prototype tests • Electronics • Main orders and manufacture • Schedule

3. 1.TOF Design

4. Options of barrel TOF The option of barrel TOF is determined after many discussions in June, 2005. Two layers of scintillator will be used for barrel. • RICH or Imaging system need more space and money. • CCT has too few photoelectrons to get good time reso. • MRPC is under test. CsI Calorimeter Barrel TOF Drift Chamber Endcap TOF

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

6. 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

7. 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

8. MRPC’s option is given up at last. Because it is too urgent and need more R&D on the following three aspects: 1) bakelite Plate 2) long strip readout 3) stability of running Also the PID capability will not improve much if MRPC is used, because the non-TOF contribute about 60ps. Anyway the experiments will go on in our group.

9. Cerenkov options • CCT(Correlated Cerenkov Timing) has been given up too. • Its principle is to measure the time of the cerenkov light to separate particles. • We did experiments and simulations. There are too few PEs to get good time reso. Number of photoelectrons in right or left PMT versus hit position from CCT simulation.

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

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

12. Cerenkov options • New DIRC: • Measure the time and one-dimension position • It uses APD or multi-channel plate 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. • This option is under investigation and may be used as the upgrade for BESIII TOF.

13. 2.Alignment and mechanical design

14. Barrel TOF Dimension • Banded to MDC outer barrel of Carbon-fiber • R-direction space: 81cm-92.5cm • Scintillator Length: 2320mm • Coverage:~82% • Pieces:88 /layer • Thickness: 50mm /layer

15. 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.

16. Mechanical design • Connecting design of Barrel TOF HV cable for PMT Preamp is directly plugged onto the breeder board of PMT Fiber cable for calibration is out of the Housing. LV for preamp Differential signal after preamp

17. The housing of barrel TOF The housing of Endcap is similar. • Five holes at corners: • Four screw holes to fix up the housing and the scintillator . Copper inserts are used. • The last for fiber connector PMT housing Scitillator Flange of Housing. Its upper edge is cut to three lines to avoid the interference of two layers’ flanges.

18. Binding tests • Two layers of barrel TOF will be bound to the MDC carbon fiber cylinder. Before Al strip was used and it affects the energy of electron and photon. To decrease the material, the tape of 3M 898 is planed to be used. • Test is done. Bricks is as the scintillator and the gasolene bucket is as the MDC cylinder. After 17 days, it is still firm and stable and no much variation occurs. brick Gasolene bucket The tape of 3M 898

19. Endcap TOF structure

20. 3.Tests on PMT

21. Bundle of diffuser ... fiber LD Laser fiber Pulse light source system Dark box for R5924-70 Mass Tests @1T by Tokyo U (1) • The magnetic test of each PMT is done by Tokyo Univ. • Put on and off mag. field 5 times, to see if the PMT can endure the mag. field up and down. • Measure the HV at the gain of 5X105 and 1Tesla. • Measure the relative time resolution of each PMT under 1 Tesla. Ushikawa Magnet

22. Mass Tests @1T by Tokyo U (2) • Relative gain and relative time reso. By Hamamatsu By Tokyo U

23. Mass Tests@1T by Tokyo U (3) HV @ gain of 5e5 @1T Relative time reso. @1T for 500p.e.

24. Dark box LED HV head PMT R5924 fiber Signal housing Ref. PMT xp2020 HV Signal Mass Tests by IHEP (1) • Each PMT is required to be checked at IHEP also. • LED is for the light source • Four parameters need to be checked here: • Relative Gain vs HV • Absolute gain at 2000HV • Rising time for single PE • Relative time reso

25. Mass Tests by IHEP (2) Absolute gain at 2000HV PMT(xp2020） LED e PMT(R5924） shield ………… SPE ………… Get the absolute gain of R5924 by measure the SPE. background

26. Absolute gain at 2000HV • The gain by the SPE method is consistent with the manual. • The absolute gain at 2000V is between 5E6 and 2E8

27. Mass Tests by IHEP (3) Rising time of SPE Using 1GHz digital oscilloscopes, we get rising time of SPE of PMTs. It takes about two hours to test Four PMTs, so we can measure all the PMTs in about one month. Rising time vs HV Dark box LED HV head PMT fiber Signal shield housing oscilloscope

28. Rising time of SPE • The rising time of SPE is about 2.32 +- 0.15 (ns).

29. Mass Tests by IHEP (4) Relative time reso. Rising time: 5.75ns PMT signal LED Driver Rising time ~1ns Width ~10ns Peak ~4V

30. Relative time reso. • The relative time reso. is 59.7 +- 0.5 with about 2000 photon electronics.

31. 4.Beam tests and prototype tests

32. Comparison of wrapping materials (Barrel) Pakage Atte. length (cm) ESR 400.35.2 Teflon 365.9 4.9 Millipore 317.8 6.1 Al film 296 .9 8.6 Tyvek 290 .2 8.3 (a) amplitudes of the bar wrapped with different materials (b) reflectivity of the materials and transmission spectrum of EJ-200

33. Comparison of wrapping materials (Barrel) Fig.1 Mirror reflect material Fig.2 Diffuse reflect material Al film is best for barrel, the time reso. can be less than 90ps.

34. Simulation on reflectivity • 70~80% give better time reso.; consistent with our experiments.

35. Time reso. Of different Scintillator (Endcap) BC404 is better than BC408, and their time resolution can be less than 80ps. Different scintillators

36. Comparison of wrapping materials (Endcap) Various wrapping Tyvek and ESR can give similar time reso. But ESR can give bigger signal. So ESR will be used in Endcap.

37. Beam tests on TOF protype • TOF protype includes: Scin., PMT, Preamp, 18m cable, VME readout board of FEE • Other systems are working • The particles are electron, pion and proton. Pion:104±11ps proton:70±2ps Electron:94±3ps

38. 5.Electronics

39. Mass production finihed. Preamp • Gain :10; • rise time <2ns; • Integral non-linearity <1% • Differential output , • noise<20mV; • Low power, 0.3W; less heat in the housing.

40. VME board: Charge measurement may be a problem. • HPTDC and online Compensation: <25ps • Charge-to-Time Converter: pulse height measured by HPTDC • synchronous with the beam with jitter lower than 20ps 3Versions: TOT->VT->QT. The 3rd Version is under tests.

41. Time resolution of Electronics • Signal from PMT is splitted two and each goes to one channel. • The time reso. of FEE <25ps.

42. 6. Main orders and manufacture

43. Main orders and manufacture (1) Finished! Most Money spent. • PMT: • Hamamatsu R5924-70/assy, 525, 17% abundance • Before March 10, 2006, deliver • Scintillator: • Saint-Gobain: BC408 for barrel and BC404 for endcap • before May 15, 2006 deliver, Now Saint-Gobain says it will be delayed to August.!! • Connectors: Having arrived. • Differential Signal connectors: LEMO • HV connectors: LEMO 05, special for thin HV cables. • Preamp input connectors: special made by Suzhou Huaye co. in China. • Cables: Having arrived. • Differential Signal cable: special made by Tianjin Cable co. in China • HV cable: Germany Draka cable, type # HTC-50-1-1, specially made for CERN and DESY.

44. 3. Main orders and manufacture (2) Unfinished! Mounting and Calibration. • Housing of PMT • Special support metal ring needed when binding TOF onto MDC • Assembly cable and their connectors of HV and LV • 3M tape of 898 • Padding material between the two layers of scintillators • Laser monitor system: fiber, LD, dark box

45. 7. Schedule

46. Schedule of BESIII

47. Milestone of BESIII • 2003.3, BEPCII project agreed by Government. • 2005.12, MC finished assembly • 2006.7~2006.12, Elec., trigger and DAQ assembly and commissioning • 2006.9~2006.11, Joint magnetic field mapping • 2006.12~2006.2, EMC barrel installation • 2007.2,DC and TOF installation • 2007.6~2007.9, Joint commissioning

48. Schedule of TOF

49. 8. Summary • TOF option is determined and the upgrade to new Cherenkov is under consideration. • Main orders and manufacture have been finished. • PMT and scintillator meet our requirements. • Prototype test is OK. • Preamp is good and 3rd FEE is under tests ! • schedule is OK.

50. The End Thanks a lot!