1. 1 ALICE T0 detector W.H.Trzaska (on behalf of T0 Group) LHCC Comprehensive Review, March 2003

2. W.H.T.LHCC Comprehensive Review, March 20032 Evolution of T0 detector concept Initial proposal (TP, MoU) one detector does it all (MCP) cost ~1.5 MCHF (Greece, Russia) Fall 2000 split of FMD into 3 sub.detectors:  Si FMDV0  Si FMD, V0 and T0  T0 (cost ~200 kCHF) Spring 2001 Choice of PMT-based T0 (worked-out by a Russian team) Spring 2002 Finland commits 200 kCHF to T0 and joins the T0 collaboration

3. W.H.T.LHCC Comprehensive Review, March 20033 T0 must work for all ions and for all energy densities central minimum bias

4. W.H.T.LHCC Comprehensive Review, March 20034 Main requirements: Precise timing (50 ps) also on-line Main LVL0 trigger Rough on-line vertex (1.5 cm) Beam – gas suppression Pre-trigger for TDR Event spacing 25 ns (pp) Provide backup for V0 and FMD Operates in the magnetic field (0.5 T) Huge dynamic range (almost 1:1000)

5. W.H.T.LHCC Comprehensive Review, March 20035 T0 – the final configuration: Two arrays of 12 PMTs with quartz radiators T0 Right ( + 0.7 m) T0 Left ( - 3.5 m) Two shoe boxes of fast electronics inside the magnet (+5 m and –5 m) Few creates of electronics outside the magnet Laser calibration system also outside the magnet

6. W.H.T.LHCC Comprehensive Review, March 20036 Output signals: T0 = (t r +t l )/2+t d T0 v = t r -t l (ON/OFF adjustable during run) T0-L, T0-R, Coinc Time and energies (all 24 PMTs) 3 levels of sum energy Low Medium High

7. W.H.T.LHCC Comprehensive Review, March 20037 T0 Left & T0 Right arrays: T0 L -5 <  < -4.5 T0 R 2.9 <  < 3.3

8. W.H.T.LHCC Comprehensive Review, March 20038 Mechanics – T0 Right

9. W.H.T.LHCC Comprehensive Review, March 20039 T0 Left

10. W.H.T.LHCC Comprehensive Review, March 200310 T0-Right 1:1 prototype: T0-Right 1:1 prototype:

11. W.H.T.LHCC Comprehensive Review, March 200311 Front view:

12. W.H.T.LHCC Comprehensive Review, March 200312 Back view:

13. W.H.T.LHCC Comprehensive Review, March 200313 End-cups on the base side:

14. W.H.T.LHCC Comprehensive Review, March 200314 Mounting of the optical fibre (  0.4 mm)

15. W.H.T.LHCC Comprehensive Review, March 200315 PiLaser PiLaser 400 nm pulse width <40ps roughly 400mW optical peak out of the fibre

16. W.H.T.LHCC Comprehensive Review, March 200316 Possible location of shoe boxes: Box 50 W Box 50 W 12 PMT full current <15 W

17. W.H.T.LHCC Comprehensive Review, March 200317 Inside the shoe box: Dual CFD Unit Dual CFD Unit

18. W.H.T.LHCC Comprehensive Review, March 200318 Characteristics of the Dual CFD Unit

19. W.H.T.LHCC Comprehensive Review, March 200319 Pre-TDR timetable Production completed by July 2005 Fully assembled T0 Tests before shipment to CERN Oct. 2005 Shipment to CERN – November 2005 Final tests – December 2005 Installation in ALICE – March 2006

20. W.H.T.LHCC Comprehensive Review, March 200320 Pre-TDR financing 200 kCHF from Finland Sufficient to cover the detector and front- end electronics Readout electronics and integration with DAQ Collaboration with TOF group Greek contribution

21. W.H.T.LHCC Comprehensive Review, March 200321 Highlights of 2002: Completion of the first draft of TDR (100 pages!) Mechanical prototype of T0 Right Final multiplicity resolution simulations Electronic prototypes: Dual CFD Unit (2 prototypes) Mean timer Circuit for generating T0 V signal Choice of laser and the layout of the laser calibration system

22. W.H.T.LHCC Comprehensive Review, March 200322 Still to be chosen: Final choice of time discriminators (test run @ CERN in July 2003) Final configuration of readout electronics, DAQ and trigger collaboration with TOF discussions with the Greek team

23. W.H.T.LHCC Comprehensive Review, March 200323 Measured performance of CFDU (JYFL) prototype 5.3 ps/ch Jitter = 25 ps (fwhm)

24. W.H.T.LHCC Comprehensive Review, March 200324 The third option: T0T0 T logA

25. W.H.T.LHCC Comprehensive Review, March 200325 Mean timer prototype

26. W.H.T.LHCC Comprehensive Review, March 200326 T0 V DC Fast digitiser for T0 V signal Range of coded time intervals ±2.5 ns Digitisation step 20 ps (for 8-bit) Dead time not more than 25 ns TAC + Flash ADC

27. W.H.T.LHCC Comprehensive Review, March 200327 T0 V DC performance Delay [ns] vs. channel number Calibration spectrum

28. W.H.T.LHCC Comprehensive Review, March 200328 Cables and connection from L3 HV cables 2 x 12 Coaxial cables Thresholds2 x 12 Bunch crossing2 x 1 Time individual2 x 12 Output Amplitudes2 x 12 TRD wake up2 x 4 T0 right/left2 x 1 Optical fibre 2 x 12

29. W.H.T.LHCC Comprehensive Review, March 200329 General, preliminary readout scheme for T0:

30. W.H.T.LHCC Comprehensive Review, March 200330 Layout and connections:

31. W.H.T.LHCC Comprehensive Review, March 200331 Large change compared to the previous version of PYTHIA: Efficiency of registration of p-p collisions