TOP R&D status Noriaki Sato (Nagoya Univ.) 2005.04.20 Super - - PowerPoint PPT Presentation

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/vz

g(λ)

vg(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

Test Counter

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 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 255cmL × 40cmw × 2cmT × 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,

σTTS ∼ 30 ps.

! ! ! !

Forward

SL10 Shown later in detail ⇒

Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.4/22

TOP Performance

2GeV/c, 90◦ π K Performance Study by MC simulation. Separation Power S = ∆T OP + ∆T OF σtime ×

• Npe

σtime ≃ σpolish ⊕ σTTS ⊕ σchro. Target > 4σ@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 Npe at longer wave length → Reduce chromatic dispersion

QE 5 10 15 20 25 30 35 40 45 50 100 200 300 400 500 600 700 800 900 1000

Multi-Alkali GaAsP GaAs

Wavelength(nm) Q.E.(%)

Group velocity

0.17 0.175 0.18 0.185 0.19 0.195 0.2 0.205 0.21 100 200 300 400 500 600 700 800 9001000

lambda(nm) group velocity(m/ns)

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) ∼ µm GaAs (BINP) ∼ µm: Just delivered Measured MCP-PMT HPK BINP photo- multi-alkali multi-alkali cathode GaAsP (GaAs) MCP ch φ 6µm # 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 × 106 Good performance as the same level of multi- alkali is

• bserved

for GaAsP photo-cathode MCP-PMT. TDC: σT T S ∼ 30ps

multi-alkali

2000 4000 6000

• 20
• 10

10 20 TDC(time walk correction)

σTTS ≈ 32ps GaAsP

1000 2000 3000

• 20
• 10

10 20 TDC(time walk correction)

σTTS ≈ 31ps

2000 4000 6000

• 20
• 10

10 20 2000 4000 6000

• 20
• 10

10 20 TDC(time walk correction)

Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.8/22

TOP Performace w/ GaAsP PMT

> 4σ@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 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% Measurement Multi-photons irradiate by LED. Efficiency is measured with single photon by pulse laser(@400nm)

e-

Al prevention layer MCP plates Anode plate

laser LED

Filter Filter

MCP-PMTs

Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.10/22

Lifetime: Q.E. of HPK

Measurement Q.E. lifetime

∼ 700 mC/cm2 output for

• ne year operation.

(BG rate ×20) Rapid efficiency drop for PMT w/o Al layer

⇒ Need Al layer

Life-Time -Output Charge vs Relative QE-

0.2 0.4 0.6 0.8 1 1.2 1.4 10 20 30 40 50 60 70 80 Output Charge (mC/cm2)

Relative QE

AL no(R3809U-50 YA0071) AL yes(R3809U-50 CT0790)

~1month

Setup was changed.

Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.11/22

Lifetime: Q.E. of BINP

0.2 0.4 0.6 0.8 1 1.2 1.4 100 200 300 400 500 600 700 800

noAl (11) Al_low (32) Al_high (35 ) hpk6_noAl hpk6_Al 1kHz_noAl(6) 1kHz_Al(38)

Output Charge (mC/cm )

2

RelativeQE (%)

w/o Al w/ Al

1year operation

Need Al-layer, too. Lifetime ∼ 300mC/cm2 even w/ Al layer

⇒ Need effort (Vacuum level)

Status of TOP Counter, 2005.04.20 Super B-Factory Workshop – p.12/22

Lifetime: Gain

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 100 200 300 400 500 600 700 800

noAl (11) Al_low (32) Al_high (35) hpk6_noAL hpk6_Al 1kHz_noAl(6) 1kHz_Al(38)

Output Charge (mC/cm )

2

Relative Gain

Gain is almost stable (> 80%@700mC/cm2) 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 µm # of MCP 2 stage # pixel/size 1×4 / 5mm×22mm Geometrical C.E. 50%

• Eff. area(2cmT)

77% Gain (HV) 2× 106 (−3.5 kV)

σT T S(HV, B) ∼30ps (−3.5 kV, 1.5T)

Gain > 106,

σT 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.

σT T S 100ps at 1.5ns delay ⇒ Improvement w/ CFD : σT 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

⇒ ∼ 4σ 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