08/31/02PID TOP Counter R & D Status — PID and Physics — TOP Counter — R&D Status Katsumi Senyo Nagoya University

08/31/02PID PID and Physics B->  DK/D  85.2± ± ±3.8 B->K  /  Preliminary!

08/31/02PID TOP Counter Performance(K/pi separation) TOP ideal performance: Better than sig. 4

08/31/02PID PID and Physics Current PID devices TOP(expected perf.)

08/31/02PID Time Of Propagation(TOP) Counter x z y 20mm PMTs Fused silica(n=1.47) Reflection mirror 200mm A few meters

08/31/02PID TOP Counter MAPMT Crystal Bar 1m

08/31/02PID PID Devices (3)  Cerenkov Counter A charged particle velocity greater than the (local phase) velocity of light →Radiating Cerenkov light Cerenkov cone half angle: cos  = 1 /n 

08/31/02PID DIRC(Detection of Internally Reflected Cherenkov light) and TOP Counter DIRC: Radiation angle -> X-Y position 1m1m TOP: Radiation angle -> Prop. Time-X position Both TOP and DIRC give a hyperbolic projection image of Cherenkov light. Time or

08/31/02PID TOP Counter L y z qzqz PMT Radiation anglePropagation time Short Propagation time:  - like Long Propagation time : K - like

08/31/02PID  What’s problem in DIRC? DIRC (cont.) Huge Stand-off Volume Is really such a dead volume needed? ~4m

08/31/02PID 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. １ ２ ３ Readout Propagation times of １,2,3 are different

08/31/02PID TOP Counter TOP x （ mm ） TOP x （ mm ） （ ns ） 30 photons observed in typical case. Unfolding

08/31/02PID 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.

08/31/02PID MAPMT R & D HPK R5900-U-L16 – Transit Time Spread~ ７５ ps – channel width １ mm Collaboration w/ HPK Insensitive region

08/31/02PID Fused Silica bar R & D Δt ~150ps even after 4m transition Improved Polish and Finish Previous Polish

08/31/02PID Time v.s. X plot (Beam test result) 2.5GeV/c pi2 line on Nov,2001. Good relation of photon propagation time and X position at the edge is observed as expected. Preliminary! 200k events concentrated plot

08/31/02PID TOP Counter – Installed in Super-Belle   （ 4s ） → BB   Installing Belle detector… r = 1m 30  < q < 140  barrel region P(K/  )

08/31/02PID Bar TOP v.s. Mirror TOP(MC Study) Separability > 4 in whole coverage of Super Belle

08/31/02PID 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.

08/31/02PID DIRC (cont.)

08/31/02PID PID and B Physics  Flavor Tagging － Determine a flavor of B P K < 1.5 GeV/c  Rare Decays including K and    －  B->K  /  DK/D    2.0 < P K < 4.0 GeV/c

08/31/02PID PID System at Belle

08/31/02PID DIRC Improvement  Focusing DIRC  Photon Propagation Time SLAC-PUB-8989 The Next Generation of Internally Reflected Imaging Counters, Sep.2001

08/31/02PID TOP Counter (cont.) – HPK R5900-U-L16 time res. ７５ ps channel width １ mm 30 photons observed in typical case

08/31/02PID TOP Counter(Bar width) 22 cc cc cc cc K  K  K  K  50mm100mm150mm200mm The bar width should be 200 mm or larger in current analysis scheme.

08/31/02PID TOP Counter - Application  Detected #Photon : 30~100

08/31/02PID TOP Counter - Separability S = 10  Mom. p = 4GeV/c,  ＝ 90° （ L = 2m ）

08/31/02PID Separability for B-> 