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Development of RICH Counters Toward the KEKB/Belle Upgrade

10 th International Conference on Instrumentation for Colliding Beam Physics (INSTR08). Development of RICH Counters Toward the KEKB/Belle Upgrade. Toru Iijima Nagoya University. March 3, 2008 @ BINP, Novosibirsk, Russia. Contents. I cannot cover all the proposed idea, developments

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Development of RICH Counters Toward the KEKB/Belle Upgrade

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  1. 10th International Conference on Instrumentation for Colliding Beam Physics (INSTR08) Development of RICH Counters Toward the KEKB/Belle Upgrade Toru Iijima Nagoya University March 3, 2008 @ BINP, Novosibirsk, Russia

  2. Contents I cannot cover all the proposed idea, developments for super-KEKB. • Introduction • Quartz-based RICH • Time-Of-Propagation Counter • Aerogel-based RICH • Proximity Focusing Aerogel RICH • Summary Toru Iijima, INSTR08 @ BINP, Novosibirsk

  3. Super-Belle PID (an option) TOP Counter Aerogel-RICH Tight space limitation Barrel: DR = 10-20cm Endcap: DZ = 28cm 1.5T 1.2m 2.6m e- 8.0GeV e+ 3.5GeV There are also other options: Focusing-DIRC, TOF. • 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 Toru Iijima, INSTR08 @ BINP, Novosibirsk

  4. Key Technology: Radiators Interferogram • Silica aerogel • Improved transmission by new recipie. • LT > 40mm for n=1.04-1.05 • Hydrophobic for long term stability Transmission length at  = 400nm ◆2005-2006 ▲2004 ■Before 2003 Transmssion length Refractive index • Quartz (fused Silica) Accurately polished to preserve the Cherenkov angle info. after many internal reflections. • Polish: 0.5nm • Figure: 0.6mm • Squareness: ±0.3mrad Toru Iijima, INSTR08 @ BINP, Novosibirsk

  5. http://tennis.dunlop.co.jp/gear/racket/aero/index.html Aerogel Useful for Sports ? Aerogel is very fragile, but have the highest withstand load/ mass. Aerogel powders are put in carbon fibers to increase the stiffness without increasing its mass. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  6. Key Technology: Photodetectors • MCP-PMT • Micro-channel-plate PMT • HAPD • Hybrid Avalanche Photodiode • Geigermode-APD High gain, Q.E., C.E. Good time resolution Good effective area in magnetic field (1.5T) Toru Iijima, INSTR08 @ BINP, Novosibirsk

  7. Time-Of-Propagation Counter Accurately polished quartz & precision timing Toru Iijima, INSTR08 @ BINP, Novosibirsk

  8. TOP or 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) Measurement coordinates Toru Iijima, INSTR08 @ BINP, Novosibirsk

  9. 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. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  10. 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 Toru Iijima, INSTR08 @ BINP, Novosibirsk

  11. 1x4 MCP-PMT (SL10) • 1x4 linear-anode MCP-PMT for TOP readout. • Developed under collab. with Hamamatsu Photonics. Confirmed gain > 106 & TTS=30ps(s) in B=1.5T magnetic field. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  12. GaAsP photo-cathode ( alkali p.c.) Higher quantum-efficiency at longer wavelength → less chromatic error Light propagation velocity inside quartz Chromatic Dispersion Variation of propagation velocity depending on the wavelength of Cherenkov photons Photon sensitivity at longer wavelength shows the smaller velocity fluctuation. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  13. GaAsPphotocathode 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 Single p.e. 0.5ns/div 20mV/div Gain～ 0.64×106 Target structure GaAsP MCP-PMT TTS～35ps Toru Iijima, INSTR08 @ BINP, Novosibirsk

  14. YH0053 YH0056 YH0057 YH0081 Monochrometer GaAsP MCP-PMT(2) MCP-PMT Old sample New sample X Spot Y PD • QE uniformity Check QE distribution by moving stage  Good performance in recent sample • Multi-alkali p.c. without Al protection To improve correction efficiency a) 3-layer MCP-PMT; test with BINP b) Low gain operation to suppress ion feedback Toru Iijima, INSTR08 @ BINP, Novosibirsk

  15. Performance with GaAsP 3.5s K/p for 4 GeV/c, q=70ﾟ • K/p separation power • GaAsP photo-cathode + >400nm filter, CE=36% Toru Iijima, INSTR08 @ BINP, Novosibirsk

  16. 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 Toru Iijima, INSTR08 @ BINP, Novosibirsk

  17. Lens Pin gauge Mirror Focusing Mirror • Check accuracy of mirror shape • Peak position of spherical mirror wrt. quartz edge • By 3D measurement system at Nagoya-univ • Correct with the result of flat planes • 0.33±0.30±0.20mm outside from bar edge • Acceptable in simulation • Cross check by interferometer in Okamoto optics work, inc. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  18. K/p separation power GaAsP photo-cathode(+>400mm filter), CE=36% Performance of Focusing TOP 4.3s separation for 4GeV/c Toru Iijima, INSTR08 @ BINP, Novosibirsk

  19. TOP Configuration Summary Focusing type can reduce the dead space and remove middle PMT. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  20. Proximity Focusing Aerogel RICH Highly transparent aerogel + Photon Imaging Toru Iijima, INSTR08 @ BINP, Novosibirsk

  21. 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. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  22. NIM A521(2004) 367 Beam Test w/ Flat Panel PMT Typical Results s0 = 14.8 mrad. <Npe> = 6.2 4s K/p @ 4GeV/c Want more photons ! 4×4 array of H8500 52.5mm pitch  84% effecive area. 1024 channel Two MWPC for tracking Toru Iijima, INSTR08 @ BINP, Novosibirsk

  23. RICH with Multiple Radiators NIM A548(2005)383 • Demonstration of principle • 4×4 array of H8500 (85% effective area) sc=22.1mradNpe=10.7 Conventional 4cm thick aerogel n=1.047 sc=14.4mradNpe=9.6 Multiple Radiators 2 layers of 2cm thick n1=1.047, n2=1.057 p/K separation with focusing configuration ~ 4.8s @4GeV/c Toru Iijima, INSTR08 @ BINP, Novosibirsk

  24. PID Capability dE/dx (CDC) Kaon Cherenkov Threshold Improvement by TOF ? Based on a likelihood approach. Simulation w/ the level of bkg. expected at Super-Belle. Focusing radiator improves PID for p>3GeV/c Toru Iijima, INSTR08 @ BINP, Novosibirsk

  25. 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) Test at bench 3 p.e. 1 p.e. Total gain ~ 5x104 2 p.e. 2 p.e. 1 p.e. 3 p.e. S/N = 8-15 for single p.e. 4 p.e. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  26. HAPD Readout ASIC • Features: • High density front-end electronics (100K channels) • High gain with low noise amplifiers • Deadtime-less readout scheme (pipeline) • Basic parameters • Rohm 0.35mm CMOS) • Shaping time = 0.3-2.0ms • VGA = 1.25-20 • 18 channels/chip • 3mW/channel □4.93[mm] Toru Iijima, INSTR08 @ BINP, Novosibirsk 26

  27. HPAD test w/ ASIC HAPD status • HAPD samples (+ASIC) are being tested. 1 4 Response to single photon irradiation 2 12 Sum of 36 channels ch1 ch4 ch12 ch2 Effects due to electric field distortion at edge Need be tested in the magnetic field. • Plan to have a beam test with aerogel+HAPD in this month. Toru Iijima, INSTR08 @ BINP, Novosibirsk 3 working HAPD samples at hand. Additional couple of samples soon.

  28. Other possibilities 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) BURLE 85011-501 Cherenkov Photons 17deg max. for n=1.05 G-APD □1~3mm Toru Iijima, INSTR08 @ BINP, Novosibirsk

  29. RICH w/ TOF Capability PMT Ring Hit DTOF1 + DTOP Aerogel DTOP IP Window Hit DTOF2 w/ L+D DTOF1(K-p) L ~ 1.8m D ~ 0.2m • 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). Toru Iijima, INSTR08 @ BINP, Novosibirsk

  30. December 2005 @ KEK-PS T2 Beam Testw/ 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) Aerogel radiator Cherenkov photon from aerogel 1.053 1.045 Cherenkov photon from window MWPC MWPC Time resolution for “window hits” (Time walk corrected) TOF test w/ beam p and p (2GeV/c) Improvement in K/p separation s = 34.3±1.1ps • = 36.2±1.3ps p p Toru Iijima, INSTR08 @ BINP, Novosibirsk Start counter: HPK R3809U MCP-PMT 1cm quartz radiator Start time resolution = 10ps TDC count(/25psec)

  31. Impact of PID improvement B0gr0g Luminosity loss / gain Completely different world with excellent PID detectors! B0gp+p- 31 Toru Iijima, INSTR08 @ BINP, Novosibirsk

  32. Summary Stay Tuned. • 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. Toru Iijima, INSTR08 @ BINP, Novosibirsk

  33. Backup slides Toru Iijima, INSTR08 @ BINP, Novosibirsk

  34. 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

  35. 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 Toru Iijima, INSTR08 @ BINP, Novosibirsk

  36. Focus Mirror Possible configuration • Detector type • 3-readout type • Optimized propagation length • Simple configuration  less technical issue • Simple ring image  easy reconstruction • Focusing type • Correct chromaticity • 2/3 PMTs • Cost • Small dead space • Easy to replace PMTs because of no middle PMT • Complicated ring image • Need noble reconstruction method • May need more simulation study to check robustness

  37. Possible configuration • Photo-cathode of MCP-PMT • Multi-alkali • Almost established production • Enough lifetime • GaAsP • Better efficiency at longer wavelength • Need more production R&D and lifetime test • Multi-alkali without Al protection layer on MCP (option) • Better efficiency (x1.6) • Almost established production, but need some modification to improve lifetime (3-layer MCP, operation with lower gain, etc.) GaAsP MCP-PMT

  38. Single Photon Angle Resolution Emission point uncertainty dominates @ d > 2cm Main contributions come from Detector granularity Emission point uncertainty All other contributions (not fully understood yet) Toru Iijima, INSTR08 @ BINP, Novosibirsk

  39. Beam Test Results ofMulti-Radiator Aerogel-RICH Toru Iijima, INSTR08 @ BINP, Novosibirsk

  40. TOF in Aerogel-RICH Worth for studying ! Toru Iijima, INSTR08 @ BINP, Novosibirsk

  41. Time resolution for Ring Hits TDCBURLE-TDCSTART COUNTER • Distribution of the hits on MCP-PMT (13 channels were readout). • Corrected distribution using the track information. • = 51.4±1.1ps 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. Toru Iijima, INSTR08 @ BINP, Novosibirsk

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