TOP Counter R & D Status

1. TOP Counter R & D Status Katsumi Senyo Nagoya University • PID and Physics • TOP Counter • R&D Status PID Workshop@Nagoya

2. PID and Physics B->Kp/pp B->DK/Dp 85.2±10.1 12.3±3.9 Preliminary! 0.4±3.8 PID Workshop@Nagoya

3. TOP Counter Performance(K/pi separation) TOP ideal performance: Better than sig. 4 PID Workshop@Nagoya

4. PID and Physics TOP(expected perf.) Current PID devices PID Workshop@Nagoya

5. Time Of Propagation(TOP) Counter Reflection mirror 200mm y z x 20mm A few meters PMTs Fused silica(n=1.47) PID Workshop@Nagoya

6. TOP Counter Crystal Bar 1m MAPMT PID Workshop@Nagoya

7. PID Devices (3) • Cerenkov Counter A charged particle velocity greater than the (local phase) velocity of light →Radiating Cerenkov light Cerenkov cone half angle: cosq = 1/nb PID Workshop@Nagoya

8. DIRC(Detection of Internally Reflected Cherenkov light) and TOP Counter DIRC: Radiation angle -> X-Y position TOP: Radiation angle -> Prop. Time-X position Time or Both TOP and DIRC give a hyperbolic projection image of Cherenkov light. 1m PID Workshop@Nagoya

9. TOP Counter y L z PMT qz Radiation angle Propagation time Short Propagation time: p - like Long Propagation time : K - like PID Workshop@Nagoya

10. DIRC (cont.) • What’s problem in DIRC? Huge Stand-off Volume ~4m Is really such a dead volume needed? PID Workshop@Nagoya

11. TOP Counter • The 3 dimension information of the Cerenkov cone is resolved with time and x position at the cross section of the fused silica. Propagation times of １,2,3 are different ３ ２ １ Readout PID Workshop@Nagoya

12. TOP Counter （ns） （ns） Unfolding TOP TOP x x （mm） （mm） 30 photons observed in typical case. PID Workshop@Nagoya

13. Key Issues on TOP Counter R & D • Good timing resolution(~100ps) on a single photon measurement w/ position-sensitive(~1mm) MAPMT. • Precise fused silica bar production on geometry and smoothness (~ Å). • Sophisticated analysis method. PID Workshop@Nagoya

14. MAPMT R & D HPK R5900-U-L16 • Transit Time Spread~７５ ps • channel width １mm Insensitive region Collaboration w/ HPK PID Workshop@Nagoya

15. Fused Silica bar R & D Improved Polish and Finish Previous Polish Δt ~150ps even after 4m transition PID Workshop@Nagoya

16. Time v.s. X plot (Beam test result) 2.5GeV/c pion @KEK-PS pi2 line on Nov,2001. 200k events concentrated plot Good relation of photon propagation time and X position at the edge is observed as expected. Preliminary! PID Workshop@Nagoya

17. TOP Counter – Installed in Super-Belle Installing Belle detector… • r = 1m • 30 < q < 140barrel region P(K/p) q Υ（4s） → BB p+p- K+p- PID Workshop@Nagoya

18. Bar TOP v.s. Mirror TOP(MC Study) Separability > 4 in whole coverage of Super Belle PID Workshop@Nagoya

19. Summary • TOP Counter is a promising PID device at next-generation B factories. • R & D is in good shape. • Beam test results will be performed on Nov. PID Workshop@Nagoya

20. DIRC (cont.) PID Workshop@Nagoya

21. PID and B Physics • Flavor Tagging －Determine a flavor of B PK < 1.5 GeV/c • Rare Decays including K and p • － B->Kp/pp , DK/Dp • 2.0 < PK < 4.0 GeV/c PID Workshop@Nagoya

22. PID System at Belle PID Workshop@Nagoya

23. DIRC Improvement • Focusing DIRC • Photon Propagation Time SLAC-PUB-8989 The Next Generation of Internally Reflected Imaging Counters, Sep.2001 PID Workshop@Nagoya

24. TOP Counter (cont.) • HPK R5900-U-L16　time res.　　７５ ps • channel width １mm 30 photons observed in typical case PID Workshop@Nagoya

25. TOP Counter(Bar width) 50mm 100mm 150mm 200mm c2 K p K p K p p K qc qc qc qc The bar width should be 200 mm or larger in current analysis scheme. PID Workshop@Nagoya

26. TOP Counter - Application • Detected #Photon : 30~100 PID Workshop@Nagoya

27. TOP Counter - Separability Mom.　p = 4GeV/c, q ＝ 90° （L = 2m） S = 10 s PID Workshop@Nagoya

28. Separability for B->pp PID Workshop@Nagoya