PID Upgrade for Super-KEKB / Belle BESS-Belle-CLEO-BaBar 2007 Joint Workshop on Charm Physics PID Upgrade for Super-KEKB / Belle Toru Iijima Nagoya University November 27, 2007

Toru Iijima, BBCB2007 @ IHEP, Beijing Contents Introduction Quartz-based RICH Time-Of-Propagation Counter Aerogel-based RICH Proximity Focusing Aerogel RICH Summary Appology; I cannot cover all the proposed idea, developments for (genric) super-B. 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Super-Belle PID (an option) To cope with increased background (present x ~20) To improve the performance. Target: > 4s at 4 GeV/c Novel Ring Imaging Cherenkov Counters w/ advanced radiator & photo-detection technologies e- 8.0GeV e+ 3.5GeV 2.6m 1.2m 1.5T TOP Counter Aerogel-RICH Tight space limitation Barrel: DR = 10-20cm Endcap: DZ = 28cm There are also other options: Focusing-DIRC, TOF. 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Key Technology: Radiators Interferogram Quartz (fused Silica) Accurately polished to preserve the Cherenkov angle info. after many internal reflections. Polish: 0.5nm Figure: 0.6mm Squareness: ±0.3mrad Silica aerogel Improved transmission by new recipie. LT > 40mm for n=1.04-1.05 Hydrophobic for long term stability Refractive index Transmssion length ◆2005-2006 ▲2004 ■Before 2003 Transmission length at  = 400nm 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Key Technology: Photodetectors High gain, Q.E., C.E. Good time resolution Good effective area in magnetic field (1.5T) MCP-PMT Micro-channel-plate PMT HAPD Hybrid Avalanche Photodiode Geigermode-APD PMT MCP-PMT HPD / HAPD Geigermode-APD Gain >106 ～106 ～103 X10～100 w/ APD Quantum Eff. ～20%, ～400nm (bialkali) > 50%, ～600nm Collection Eff. 70% 60% 100% 50% Time resolution ～300ps ～30ps ～150ps Depends on readout <100ps To be checked B-field immunity × △ Depends on angle ○ Problems lifetime Noise, size 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Time-Of-Propagation Counter Accurately polished quartz & precision timing 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing Quartz based RICH Use of total internal reflection in accurately polished quartz bar. A concept was invented by B.Ratcliff et al. DIRC (Detector of Internally Reflected Cherenkov light) NIM A479(2002)1 TOP (Time Of Propagation) Counter NIM A453(2000)331 Focusing DIRC/TOP (X, Y) (X, TOP) (X, Y, TOP) TOP or Measurement coordinates 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing TOP counter Simulation 2GeV/c, q=90 deg. Cherenkov ring imaging using timing information Difference of path length  Difference of time of propagation (TOP) 150~200ps from TOP + TOF from IP with precise time resolution (s~40ps) for each photon d-ray, had. int. 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Design Quartz: 255cmL x 40cmW x 2cmT Cut at 47.8deg. to reduce chromatic dispersion Multi-anode MCP-PMT Good time resolution (<~40ps), Linear array (5mm pitch) Three readout planes MCP-PMT 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing 1x4 MCP-PMT (SL10) 1x4 linear-anode MCP-PMT for TOP readout. Developed under collab. with Hamamatsu Photonics. #MCP stage 2 Gain (HV) 2x106 (-3.5KV) MCP hole dia. 10mm Geometrical collection eff. 50% #pixel /size 1x4 / 5mmx22mm Effective area/ Total area 64% Confirmed gain > 106 & TTS=30ps(s) in B=1.5T magnetic field. 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing Chromatic Dispersion Variation of propagation velocity depending on the wavelength of Cherenkov photons Light propagation velocity inside quartz GaAsP photo-cathode ( alkali p.c.) Higher quantum-efficiency at longer wavelength → less chromatic error Photon sensitivity at longer wavelength shows the smaller velocity fluctuation. 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing Target structure GaAsP MCP-PMT GaAsP photocathode w/ Al protection layer 2 MCP layers with f=10mm hole Wave form, ADC and TDC distributions for single photon Enough gain to detect single photo-electron Good time resolution (TTS=35ps) for single p.e. pedestal single photon peak Gain～ 0.64×106 Single p.e. 0.5ns/div 20mV/div TTS～35ps 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Performance with GaAsP K/p separation power GaAsP photo-cathode + >400nm filter, CE=36% 3.5s K/p for 4 GeV/c, q=70ﾟ 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing Focusing TOP Remaining chromatic effect makes ~100ps fluctuation for TOP. Use l dependence of Cherenkov angle to correct chromaticity  Focusing system to measure qc l  qc  y position Reconstruct ring image from 3D informations (time, x and y). Mirror image Rotate PMT Focus Mirror Side view 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Performance of Focusing TOP K/p separation power GaAsP photo-cathode(+>400mm filter), CE=36% 4.3s separation for 4GeV/c 2007/11/27

Proximity Focusing Aerogel RICH Highly transparent aerogel + Photon Imaging 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Proximity Focusing Aerogel RICH Aerogel radiator (n~1.05, ~2cm) + photodetector (Dx ~ 5mm) Proximity focusing geometry No mirror complex. Suitable for collider and space experiments. >4s K/p for 0.7 < p < 4.5 GeV/c @ 4GeV/c, q(p)=310mrad. q(p)-q(K)=23mrad. Distance between aerogel to photodetector = 200mm. Track Incident angles = 17-34deg. 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Beam Test w/ Flat Panel PMT NIM A521(2004) 367 Beam Test w/ Flat Panel PMT 4×4 array of H8500 52.5mm pitch  84% effecive area. 1024 channel Two MWPC for tracking Typical Results s0 = 14.8 mrad. <Npe> = 6.2 4s K/p @ 4GeV/c Want more photons ! 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

RICH with Multiple Radiators NIM A548(2005)383 Demonstration of principle 4×4 array of H8500 (85% effective area) Conventional 4cm thick aerogel n=1.047 sc=22.1mrad Npe=10.7 Multiple Radiators sc=14.4mrad Npe=9.6 2 layers of 2cm thick n1=1.047, n2=1.057 p/K separation with focusing configuration ~ 4.8s @4GeV/c

Toru Iijima, BBCB2007 @ IHEP, Beijing Multialkari photocathode Pixel APD 144ch HAPD -10kV 15~25mm e- Newly developed under collaboration with Hamamatsu Photonics. 4 APD chips (6x6pixel/chip) 5x5mm2 pixel 64% effective area High gain: O(104) 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Other possibilities Geiger-mode APD MCP-PMT High gain(~106) Good time resolution(~50ps/p.e.) Stable operation. Need Smaller pore size (25m  <10m) Better collection eff. Lifetime ? Geiger-mode APD High gain(~106) High Q.E.(>50%) B-field immunity independent of the direction. Concerns High noise rate (~200KHz/mm) Size (~1x1mm2 3x3mm2) Radiation damage ? Light collector □3~5mm (IN) □1-2mm(OUT) G-APD □1~3mm Cherenkov Photons 17deg max. for n=1.05 BURLE 85011-501

RICH w/ TOF Capability Possible PID improvement in low momentum region. Two timings can be used; “Ring hit” : Cherenkov photons from aerogel. sphoton ~ 60ps strack ~ 60ps/sqrt(9) =20ps “Window hit”: Cherenkov photons from glass window of PMT strack ~10ps possible (from the TOF R&D @ Nagoya). Aerogel PMT IP DTOF1(K-p) D ~ 0.2m DTOP L ~ 1.8m Ring Hit DTOF1 + DTOP Window Hit DTOF2 w/ L+D

Beam Test w/ BURLE MCP-PMT December 2005 @ KEK-PS T2 Beam Test w/ BURLE MCP-PMT Multi-anode MCP-PMT BURLE 85011-501 13 channels readout by FTA820 amplifier (ORTEC) L-edge discri (Phillips) KC3781A TDC (Kaizu works) Start counter: HPK R3809U MCP-PMT 1cm quartz radiator Start time resolution = 10ps Cherenkov photon from aerogel from window MWPC Aerogel radiator 1.045 1.053 Time resolution for “window hits” (Time walk corrected) TOF test w/ beam p and p (2GeV/c) p s = 34.3±1.1ps = 36.2±1.3ps p TDC count(/25psec)

Summary RICH detectors, based on Quartz and Aerogel, are being developed for the Super-KEKB/Belle Key technologies; Radiators: Accurately polished quartz Highly transparent aerogel Photodetectors: MCP-PMT / HAPD / Geiger-mode APD Ideas to overcome performance limitations TOP counter: chromatic dispersion  GaAsP, focusing-TOP Aerogel RICH: emission point uncertainty  multiple-radiator Prototype detectors with the newly developed potodetectors will be tested in beams by summer 2008.  Finalization of detector design. Stay Tuned. 2007/11/27

Ad:BNM2008 Workshop (Jan.24-26,2008) http://superb.kek.jp/bnm2008/index.html 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing Backup slides 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Toru Iijima, BBCB2007 @ IHEP, Beijing Particle ID in Belle Calibratiopn by D*+D0p+, D0K-p+ eff.(KK) >90% fake(pK)<10% 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Motivation of PID Upgrade To cope with increasing background (x20). TOF may not survive ACC seems to be OK Improve separation for K/p, and also for m/p hopefully. Extend momentum coverage in the forward endcap. Endcap-ACC (n=1.03) functions only for flavor tagging Reduced material thickness, and more homogeneous distribution. 30% in total = 18% (ACC) + 12% (TOF) PMTs dominate for ACC Physics Targets B  pp/Kp, Dp/DK B rg/K*g (bdg/sg) B  K ll, K n n Full reconstruction Less systematics for precise measurements 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Chromaticity Detection time depending on the wavelength of Cherenkov photons Worse time resolution  Worse ring-image separation  Propagation velocity depending on l in the quartz bar

Toru Iijima, BBCB2007 @ IHEP, Beijing Focusing TOP (2) Dqc~1.2mrad over sensible l range  Dy~20mm (~quartz thickness) We can measure l dependence and obtain good separation even with narrow mirror and readout plane, because of long propagation length. Not need focusing block Dqc~1.2mrad Virtual readout screen 22mm x 5mm matrix Focusing mirror 1850mm 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Single Photon Angle Resolution Main contributions come from Detector granularity Emission point uncertainty All other contributions (not fully understood yet) Emission point uncertainty dominates @ d > 2cm 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

Beam Test Results of Multi-Radiator Aerogel-RICH

Defocusing Config. More affected by background. n1 n2 n1>n2 More affected by background. Photons from higher n layer are dumped. Overlap of K-ring from n1 and p-ring from n2.

Toru Iijima, BBCB2007 @ IHEP, Beijing PID Capability Based on a likelihood approach. Simulation w/ the level of bkg. expected at Super-Belle. Focusing radiator improves PID for p>3GeV/c dE/dx (CDC) Kaon Cherenkov Threshold 2007/11/27 Toru Iijima, BBCB2007 @ IHEP, Beijing

TOF w/ MCP-PMT High-resolution TOF using Cherenkov light Y.Enari NIM A547 (2005) 490 K.Inami A560 (2006) 303 TOF w/ MCP-PMT High-resolution TOF using Cherenkov light Small-size quartz : Cherenkov light (Decay time ~ 0) MCP-PMT : TTS < 50ps for single photon Results 1 4cm quartz radiator s(elec.) = 8.8psec Results 2 w/ improved s(elec) 1cm quartz radiator s(elec.) = 4.7psec s(TOF) = 10.6ps s(TOF) = 6.2ps Time correlated single photon counting module SPC-134 (Becker&Hickl GMbH’s)

TOF in Aerogel-RICH Worth for studying ! 1.5GeV/c 2GeV/c 4GeV/c Ring Hit -- 147ps 37ps Window Hit 323ps 184ps 47ps Worth for studying !

Time resolution for Ring Hits Obtained time resolution for Cherenkov photons from aerogel agrees well with the value from the bench tests. Resolution for the full ring (Npe~10) would be about 20ps. TDCBURLE-TDCSTART COUNTER Distribution of the hits on MCP-PMT (13 channels were readout). Corrected distribution using the track information. = 51.4±1.1ps