TOP R&D status. Noriaki Sato (Nagoya Univ.) Super B-Factory Workshop in Hawaii. Status MCP-PMT R&D Summary

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1 TOP R&D status Noriaki Sato (Nagoya Univ.) Super B-Factory Workshop in Hawaii Status MCP-PMT R&D Summary Status of TOP Counter, Super B-Factory Workshop p.1/22

2 TOP Counter Ring Imaging Cherenkov counter with precise measurement of the Time Of Propagation (and TOF) Quartz Radiator & Photon Detector Reconstruct ring image from (X, T OP ) TOP = L/v z g (λ) v g (λ): The group velocity of light Chromatic dispersion: One of the main subject for Performance Status of TOP Counter, Super B-Factory Workshop p.2/22

3 R&D Status at the Last Workshop Confirmed the principle by the test counter. Quartz-bar study Basic study was already done. Need very good polishing accuracy A Performance study by simulation Light propagation in quartz Photon detection by MCP-PMT Test Counter MCP-PMT R&D: Current Main Subject and Today s Main Topic MCP-PMT is the possible candidate of photon detector to satisfy the following requirements: Good time resolution: σ 40 ps Position sensitive: 5mm Single photon sensitive under B = 1.5T We ve developed SL10 with HPK : Basically Good Performance! A homework: cross-talk Other issues: Geometry and support structure, readout elec. should be studied and working now Status of TOP Counter, Super B-Factory Workshop p.3/22

4 Base Design Radiator: Quartz bar of 255cm L 40cm w 2cm T 18 units in φ segmented at θ = 46 to reduce chromatic dispersion error Photon detector: Multi-anode MCP-PMT at three readout planes SL10 (R&D w/ HPK) : 5mm pitch linear array, σ TTS 30 ps. Forward SL10 Shown later in detail Status of TOP Counter, Super B-Factory Workshop p.4/22

5 TOP Performance Performance Study by MC simulation. Separation Power 2GeV/c, 90 π K S = TOP + TOF σ time N pe σ time σ polish σ TTS σ chro. Target > 4σ@4 GeV/c : does not been achived Status of TOP Counter, Super B-Factory Workshop p.5/22

6 MCP-PMT with GaAs/GaAsP GaAs/GaAsP photo-cathode (SL10: multi-alkali) Higher Q.E. Increase N pe at longer wave length Reduce chromatic dispersion Q.E.(%) QE Multi-Alkali GaAsP GaAs group velocity(m/ns) Group velocity Wavelength(nm) lambda(nm) Status of TOP Counter, Super B-Factory Workshop p.6/22

7 MCP-PMT Performance TTS of MCP-PMT w/ GaAs/GaAsP may be worse due to the thickness of photo-cathode. = should be checked multi(bi)-alkali(hpk/binp) 100 A GaAsP (HPK) µm GaAs (BINP) µm: Just delivered Measured MCP-PMT HPK BINP photo- multi-alkali multi-alkali cathode GaAsP (GaAs) MCP ch φ 6µm #ofmcp anode 2stage single Status of TOP Counter, Super B-Factory Workshop p.7/22

8 MCP-PMT Performance: ADC/TDC ADC: Gain Good performance as the same level of multialkali is observed for GaAsP photo-cathode MCP-PMT. TDC: σ TTS 30ps multi-alkali GaAsP σ TTS 32ps 1000 σ TTS 31ps TDC(time walk correction) TDC(time walk correction) TDC(time walk correction) Status of TOP Counter, Super B-Factory Workshop p.8/22

9 TOP Performace w/ GaAsP PMT > can be achieved! multi-anode MCP-PMT with GaAsP cathode (SL10 w/ GaAsP) Other Issues? Lifetime Status of TOP Counter, Super B-Factory Workshop p.9/22

10 Lifetime test Two types MCP-PMT: w/ & w/o Al layer e - Al prevention layer HPK(R3809U), BINP Mutli-alkali photo-cathode Al preventaion layer Block feedback ions from MCP to photo-cathode Make photo-cathode lifetime longer C.E. decreases by 60% Filter MCP plates Anode plate laser Measurement Multi-photons irradiate by LED. Efficiency is measured with single photon by pulse laser(@400nm) MCP-PMTs Filter LED Status of TOP Counter, Super B-Factory Workshop p.10/22

11 Lifetime: Q.E. of HPK Measurement Q.E. lifetime 700 mc/cm 2 output for one year operation. (BG rate 20) Rapid efficiency drop for PMT w/o Al layer Need Al layer Relative QE Life-Time -Output Charge vs Relative QE- AL no(r3809u-50 YA0071) AL yes(r3809u-50 CT0790) Setup was changed. 0.4 ~1month Output Charge (mc/cm 2 ) Status of TOP Counter, Super B-Factory Workshop p.11/22

12 Lifetime: Q.E. of BINP RelativeQE (%) noal (11) Al_low (32) Al_high (35 ) hpk6_noal hpk6_al w/ Al w/o Al 1kHz_noAl(6) 1kHz_Al(38) 1year operation Output Charge (mc/cm ) Need Al-layer, too. Lifetime 300mC/cm 2 even w/ Al layer Need effort (Vacuum level) Status of TOP Counter, Super B-Factory Workshop p.12/22

13 Lifetime: Gain Relative Gain noal (11) Al_low (32) Al_high (35) hpk6_noal hpk6_al 1kHz_noAl(6) 1kHz_Al(38) Output Charge (mc/cm ) Gain is almost stable (> 80%@700mC/cm 2 ) If gain drops, we can raise high voltage up to recover it. 2 Status of TOP Counter, Super B-Factory Workshop p.13/22

14 Rectanglular PMT: SL10 4ch linear array MCP-PMT Photo cathode mutli-alkali MCP ch φ 10 µm #ofmcp 2stage # pixel/size 1 4 /5mm 22mm Geometrical C.E. 50% Eff. area(2cm T ) 77% Gain (HV) ( 3.5 kv) σ TTS (HV, B) 30ps ( 3.5 kv, 1.5T) Gain > 10 6, σ TTS 30ps in B =1.5 T : Confirmed SL10 Status of TOP Counter, Super B-Factory Workshop p.14/22

15 Cross-talk Time resolution becomse worse due to cross talk of neighbor signals. To reduce cross talk, divide electrodes on MCP. S/N is improved from 5to 10. S/N 5 S/N 10 Status of TOP Counter, Super B-Factory Workshop p.15/22

16 Cross-talk: TTS Measurement L.E.Discri. C.F.Discri. σ TTS 100ps at 1.5ns delay Improvement w/ CFD : σ TTS 40ps Status of TOP Counter, Super B-Factory Workshop p.16/22

17 Summary and Future Plan Summary Performance Study Need to reduce chormatic dispersion error segmented bar, GaAsP photo-cathode MCP-PMT with GaAsP photo-cathode 4σ Need to test of lifetime. Lifetime test Need Al layer at least, it is not enough, though. Cross-talk Divide electrodes, CFD TTS 40ps Future Plan Lifetime of MCP-PMT Need more effort. Test of the GaAsP photo-cathode. BINP s GaAs MCP-PMT Performance check Lifetime test Other issues Readout elec., Support structure, : working now Status of TOP Counter, Super B-Factory Workshop p.17/22

18 Personal Announcement I have another talk on the τ -physics in the Physics Parallel V, tommorow afternoon. Please come and listen! Status of TOP Counter, Super B-Factory Workshop p.18/22

19 Personal Announcement I have another talk on the τ -physics in the Physics Parallel V, tommorow afternoon. Please come and listen! Although I don t finish the preparation yet. Status of TOP Counter, Super B-Factory Workshop p.18/22

20 Backup Status of TOP Counter, Super B-Factory Workshop p.19/22

21 MCP-PMT Performance: Raw Signal HPK multi-alkali GaAsP Status of TOP Counter, Super B-Factory Workshop p.20/22

22 Readout elec.: TAC-IC Requirements Time resolution 20ps by Time to Analog Converter Low dead time 100 ps Limited double overlap gate Small size & Multi channel Test production (by VDEC) TAC with comparator, CFD Well work with 40MHz clock! Time resolution: 200 ps should be improved for the next test production Status of TOP Counter, Super B-Factory Workshop p.21/22

23 Geometry More realistic design study by simulation Quartz, Al wall, (Al honeycomb holder) Narrow space for support structure Maybe need more space Status of TOP Counter, Super B-Factory Workshop p.22/22