TOP R&D status Noriaki Sato (Nagoya Univ.) 2005.04.20 Super B-Factory Workshop in Hawaii Status MCP-PMT R&D Summary Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.1/22
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, 2005.04.20 Super B-Factory Workshop – p.2/22
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 Test Counter Light propagation in quartz Photon detection by MCP-PMT 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: � 5 mm 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, 2005.04.20 Super B-Factory Workshop – p.3/22
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, 2005.04.20 Super B-Factory Workshop – p.4/22
TOP Performance Performance Study by MC simulation. 2GeV/c, 90 ◦ π K Separation Power S = ∆ T OP + ∆ T OF � N pe × σ time σ time ≃ σ polish ⊕ σ TTS ⊕ σ chro. Target > 4 σ @4 GeV/c : does not been achived Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.5/22
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 QE 50 Q.E.(%) Multi-Alkali GaAsP 45 GaAs Group velocity 0.21 group velocity(m/ns) 40 0.205 35 0.2 30 0.195 25 0.19 20 0.185 15 0.18 0.175 10 0.17 100 200 300 400 500 600 700 800 9001000 5 lambda(nm) 0 100 200 300 400 500 600 700 800 900 1000 Wavelength(nm) Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.6/22
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) ∼ µ m Measured MCP-PMT HPK BINP photo- multi-alkali multi-alkali cathode GaAsP (GaAs) GaAs (BINP) ∼ µ m: Just delivered MCP ch φ 6 µ m # of MCP 2stage anode single Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.7/22
MCP-PMT Performance: ADC/TDC ADC: Gain ∼ 1.0 × 10 6 Good performance as the same level of multi- alkali is observed for GaAsP photo-cathode MCP-PMT. TDC: σ T T S ∼ 30ps multi-alkali GaAsP 3000 6000 6000 6000 4000 4000 2000 4000 σ TTS ≈ 31ps σ TTS ≈ 32ps 2000 2000 1000 2000 0 0 0 0 -20 -20 -10 -10 0 0 10 10 20 20 -20 -10 0 10 20 -20 -10 0 10 20 TDC(time walk correction) TDC(time walk correction) TDC(time walk correction) Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.8/22
TOP Performace w/ GaAsP PMT > 4 σ @4GeV/c can be achieved! ⇒ multi-anode MCP-PMT with GaAsP cathode (SL10 w/ GaAsP) Other Issues? ⇒ Lifetime Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.9/22
Lifetime test Two types MCP-PMT: w/ & w/o Al e - layer Al prevention layer HPK(R3809U), BINP MCP plates Mutli-alkali photo-cathode Anode plate Al preventaion layer Block feedback ions from MCP to photo-cathode Make photo-cathode lifetime laser longer Filter C.E. decreases by 60% Filter LED Measurement MCP-PMTs Multi-photons irradiate by LED. Efficiency is measured with single photon by pulse laser(@400nm) Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.10/22
Lifetime: Q.E. of HPK Life-Time -Output Charge vs Relative QE- Measurement Q.E. lifetime Relative QE 1.4 ∼ 700 mC/cm 2 output for AL no(R3809U-50 YA0071) 1.2 AL yes(R3809U-50 CT0790) one year operation. (BG rate × 20) 1 Rapid efficiency drop for PMT w/o Al layer 0.8 ⇒ Need Al layer Setup was changed. 0.6 ~1month 0.4 0.2 0 10 20 30 40 50 60 70 80 Output Charge (mC/cm 2 ) Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.11/22
Lifetime: Q.E. of BINP 1.4 RelativeQE (%) noAl (11) hpk6_noAl Al_low (32) hpk6_Al 1.2 Al_high (35 ) 1 w/ Al 0.8 0.6 0.4 w/o Al 0.2 1kHz_noAl(6) 1year operation 1kHz_Al(38) 0 0 100 200 300 400 500 600 700 800 2 Output Charge (mC/cm ) Need Al-layer, too. Lifetime ∼ 300mC/cm 2 even w/ Al layer ⇒ Need effort (Vacuum level) Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.12/22
Lifetime: Gain 1.6 Relative Gain 1.4 1.2 1 0.8 0.6 noAl (11) hpk6_noAL 0.4 Al_low (32) hpk6_Al Al_high (35) 1kHz_noAl(6) 0.2 1kHz_Al(38) 0 100 200 300 400 500 600 700 800 2 Output Charge (mC/cm ) Gain is almost stable ( > 80%@700mC/cm 2 ) If gain drops, we can raise high voltage up to recover it. Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.13/22
Rectanglular PMT: SL10 4ch linear array MCP-PMT Photo cathode mutli-alkali MCP ch φ 10 µ m # of MCP 2 stage # pixel/size 1 × 4 / 5mm × 22mm Geometrical C.E. 50% Eff. area(2cmT) 77% 2 × 10 6 ( − 3.5 kV) Gain (HV) σ T T S (HV, B) ∼ 30ps ( − 3.5 kV, 1.5T) Gain > 10 6 , σ T T S ∼ 30ps in B = 1.5 T : Confirmed SL10 Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.14/22
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 ∼ 5 to ∼ 10. S/N ∼ 5 S/N ∼ 10 Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.15/22
Cross-talk: TTS Measurement L.E.Discri. C.F.Discri. σ T T S � 100ps at 1.5ns delay ⇒ Improvement w/ CFD : σ T T S ∼ 40ps Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.16/22
Summary and Future Plan Summary Performance Study Need to reduce chormatic dispersion error ⇒ segmented bar, GaAsP photo-cathode MCP-PMT with GaAsP photo-cathode ⇒ ∼ 4 σ π/K separation @4GeV 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, 2005.04.20 Super B-Factory Workshop – p.17/22
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, 2005.04.20 Super B-Factory Workshop – p.18/22
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, 2005.04.20 Super B-Factory Workshop – p.18/22
Backup Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.19/22
MCP-PMT Performance: Raw Signal HPK multi-alkali GaAsP Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.20/22
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, 2005.04.20 Super B-Factory Workshop – p.21/22
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, 2005.04.20 Super B-Factory Workshop – p.22/22
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