1. TOF Monitor System Status F. Harris U. of Hawaii June 13, 2006

2. BESIII TOF Crucial for particle ID Barrel –Two layers, 88 counters each layer. –50mm x 60mm x 2500 mm (inner layer). –Radius from 810 to 930 mm. –BC408 Endcap –88 fan shaped pieces – each end. –BC404 Time resolution 1-layer (intrinsic): –Belle: 70 to 80 ps –Beam tests: < 90 ps –Simulation: < 90 ps K/  separation 2  separation up to 0.9 GeV/c TOF – IHEP TOF electronics - USTC

3. TOF Calibration System Hawaii is building a TOF calibration system for BESIII. (Fred Harris, Lucas Nguyen, Steve Olsen, Marc Rosen, and Gary Varner) Built such systems for both BESII and Belle. Proposal approved in March 2006. Important as system monitor and for calibration. BESII system:

4. Replace N2-dye laser with Laser Diode (405 or 440 nm)? –Simpler to use and maintain. –Longer lifetime. –~5 x 10 7 photons/pulse. –Peak power at low rep. rate: 405B -- 0.3 W 405M – 0.6 W (new) BESIII TOF Calibration System PicoQuant GmbH LDH-P

5. Dark box ADC for LD LD driver TDC... CLK Gate.G. NIM TTL attn. Gate.G. NIM TTL attn. start gate in stop Ref. PMT (ADC check) diffuser fiber bundle LD Ushiwaka Magnet Dark box for R5924-70 Will it work? U. Tokyo Measurement System

6. Generation of Laser Pulse NIM TTL CLK Gate.G. NIM TTL attn. Gate.G. attn. LD driver ～ 1.8V (max.) Trigger pulse ～ 10ns LD for LD threshold ～ 1μs Bias pulse ～ 550mV ～ 400mV Laser Pulse!! When we provide bias pulse and trigger pulse, LD generates intensive pulse ! Uses non-standard pulsing system. Safe for BESIII?

7. Choice of Laser LD has many advantages; but is light sufficient with standard pulser? N2/dye laser has plenty of light and is considerably cheaper. Tentatively choose N2/dye laser initially. LD may be an upgrade. Measure efficiency of U. of Tokyo system to determine if LD with standard pulsing has enough light. Gary Varner.

8. TOF Monitor System TOF endcap 48 fibers Laser Light splitter TOF barrel PMT TDC start ADC gate Fiber TOF barrel 176 fibers Electronic switch fiber Fiber bundles fiber connector Wrapped with steel tube § Use mirror to steer beam – like BESII. § Purchase fiber cable bundles (2 cables).

9. Use Spiricon Beam Analyzer to analyze beam and design optics – laser into fiber bundle. Optimum design? BESIII TOF Calibration System

10. Many companies interested: –Ogmentum Inc., Sales and Marketing for FiberLabs –CeramOptec –Romack –Fibertech-optica –Fiberguide Industries Many choices: (tentative) –Fiber size (100 micron core). –Connectors (FC/PC). –Single fiber jacketing (PVC furcation). –Outer jacketing (SSTL stripwound). –Multiconnector type. –Ferrule. Fiber Bundle Cables

11. 8.7 m 248 fibers (cores + cladding only) with ferrule on end 2-96 fiber bundles 2 - 28 fiber bundles (24 + 4 spares) 96 fibers with connectors (88 + 8 spares) 106 (18 spares) cables 7.5 m long with connector on one end and ferrule on other. Distribution boxes – one side clamps bundle cable; Other side has single feed through connectors 30 (6 spares) cables 2.0 m long with connector on one end and ferrule on other. 5.4 m Distribution boxes – one side: multi connector Other: single connectors (box 40 mm thick max) 9 m Total length = 21.6 m Total length = 19.7 m Cable Dimensions (May 2, 2006) Fiber Bundle Cables (need 2) Barrel TOF EC TOF

12. Fiber Connection to TOF

13. Cable Routing? Have plan; need to check cable dimensions carefully

14. Test Setup at UH Need TOF counter and readout for testing TOF laser calibration system. Have Belle BC408 TOF counter and 2 BES fine mesh phototubes. Use cosmic ray telescope. Have Caen VME TDC with computer to readout. Caen VME QDC ordered. Will use BESIII readout when ready.

15. TB Top counter Bottom counter Delay boxes 50 mv, 28 ns out PS755 scalers TOF PMT T B Test Setup NS S 40 mv, 30 ns out TBS PS711 4 ns HV S = 1200 V HV N = 1150 V HV T = 1400 V HV B = 1450 V ~2 counts/min TDC trigger

16. Test Setup – first results Telescope near middle of TOF N – B time σ = 0.87 ns S – B time σ = 0.81 ns N – S time σ = 0.61 ns No time walk correction. Need to understand resolution.

17. Much to do Complete test setup. Measure power out and pulse width of UT laser diode. Will laser diode work for us? Decide on laser. Order by end of summer. Finalize cable design, connectors, etc. Get quotes. - Order by end of summer. Install N laser, fiber cables in UH test setup. Test and finalize design. – Summer 2006. Test cable in Hawaii. Oct/Nov 2006. Ship everything to IHEP – Dec. 2006. Begin installation – Jan. 07

18. Thanks

20. Light Source ◆ Violet Laser Diode (LD) Wave Length : 408nm Violet LD Unit LD driver LD head wavelength (nm) relative output Typical Spectrum (by Nichia)

21. LD Intensity Distribution x (mm) N pe the diameter of the bundle

22. Cable CeramOptec (Kevin Bakhshpour): –Fiber: step index MM P/N UV90/100/107P (P-polyimide) (~20 – 25 K$/cable) P/N UV200/210/235P (~25 – 30 K$/cable) –6 – 8 weeks Romack (Peter Gordon): –Fiber: step index 100 micron ($1.5/m) 50 micron ($2.5.m); graded index ($0.5) –PVC Furcation tubing for single fiber cables –FC/PC connectors –jacketing?

23. Cable Fibertech-optica (Rafal Pawluczyk) –Fiber AS100/110UVPI ($0.9/m -> $9900 for fibers) AS200/220UVPI ($1.35/m -> $14,850 ) 65.2/125 ($0.13/m -> $1430) Fiberguide Industries (Tom Christie) –Fiber SFS100/110 SFS200/220 (50% more) AGI6.25/125T (13% more than SFS100) Fiber Labs (Jake Weise) –Fiber: 190 micron ($7K) 100 micron (11K) 62.5 micron ($14K) Poor efficiency