TOP R&D status - phys.hawaii.edusuperb/2005/slides/detector2/satoh/... · alkali is observed for GaAsP photo-cathode MCP-PMT. TDC: σTTS∼ 30ps multi-alkali 0 2000 4000 6000-20 -10

TOP R&D statusNoriaki 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 CounterRing Imaging Cherenkov counterwith precise measurement of the Time Of Propagation (and TOF)

Quartz Radiator & Photon Detector

Reconstruct ring image from (X, TOP )

TOP = L/vzg(λ)

vg(λ): The group velocity of light

⇒ Chromatic dispersion:One of the main subject for Performance


R&D Status at the Last Workshop

Test Counter

Confirmed the principle by the test counter.

Quartz-bar studyBasic study was already done.Need very good polishing accuracy ∼

◦A

Performance study by simulationLight propagation in quartz Photon detection by MCP-PMT

MCP-PMT R&D: Current Main Subject and Today’s Main TopicMCP-PMT is the possible candidate of photon detector to satisfy thefollowing requirements:

Good time resolution: σ � 40 psPosition sensitive: � 5 mmSingle 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


Base DesignRadiator: Quartz bar of 255cmL × 40cmw × 2cmT × 18 units in φsegmented at θ = 46◦ to reduce chromatic dispersion error

Photon detector: Multi-anode MCP-PMT at three readout planesSL10 (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 Performance2GeV/c, 90◦ π KPerformance Study by MC simulation.

Separation Power

S =∆TOP + ∆TOF

σtime× √

Npe

σtime � σpolish ⊕ σTTS ⊕ σchro.

Target > 4σ@4 GeV/c :does not been achived


MCP-PMT with GaAs/GaAsPGaAs/GaAsP photo-cathode (SL10: multi-alkali)Higher Q.E. → Increase Npeat longer wave length → Reduce chromatic dispersion

QE

0

5

10

15

20

25

30

35

40

45

50

100 200 300 400 500 600 700 800 900 1000

Multi-AlkaliGaAsPGaAs

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 9001000lambda(nm)

gro

up

vel

oci

ty(m

/ns)


MCP-PMT PerformanceTTS of MCP-PMT w/ GaAs/GaAsP may be worse due to the thickness ofphoto-cathode. =⇒ should be checked

multi(bi)-alkali(HPK/BINP) ∼ 100◦A

GaAsP (HPK) ∼ µm

GaAs (BINP) ∼ µm: Just delivered

Measured MCP-PMTHPK BINP

photo- multi-alkali multi-alkalicathode GaAsP (GaAs)

MCP ch φ 6µm# of MCP 2stage

anode single


MCP-PMT Performance: ADC/TDCADC: Gain ∼ 1.0 × 106

Good performance asthe same level of multi-alkali is observed forGaAsP photo-cathodeMCP-PMT.

TDC: σT T S ∼ 30psmulti-alkali

0

2000

4000

6000

-20 -10 0 10 20TDC(time walk correction)

σTTS ≈ 32ps

GaAsP

0

1000

2000

3000


σTTS ≈ 31ps

0

2000

4000

6000

-20 -10 0 10 200

2000

4000

6000



TOP Performace w/ GaAsP PMT

> 4σ@4GeV/c can be achieved!

⇒ multi-anode MCP-PMTwith GaAsP cathode

(SL10 w/ GaAsP)

Other Issues? ⇒ Lifetime


Lifetime testTwo types MCP-PMT: w/ & w/o Allayer

HPK(R3809U), BINPMutli-alkali photo-cathode

Al preventaion layerBlock feedback ions from MCP tophoto-cathodeMake photo-cathode lifetimelongerC.E. decreases by 60%

MeasurementMulti-photons irradiate by LED.Efficiency is measured with singlephoton by pulse laser(@400nm)

e- Al prevention layer

MCP plates

Anode plate

laser

LED

Filte

rFi

lter

MCP-PMTs


Lifetime: Q.E. of HPKMeasurement Q.E. lifetime

∼ 700 mC/cm2 output forone year operation.(BG rate ×20)

Rapid efficiency drop forPMT 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

0 10 20 30 40 50 60 70 80Output Charge (mC/cm2)

Rel

ativ

e Q

E

AL no(R3809U-50 YA0071)

AL yes(R3809U-50 CT0790)

~1month

Setup was changed.


Lifetime: Q.E. of BINP

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 100 200 300 400 500 600 700 800

noAl (11)

Al_low (32)

Al_high (35 )

hpk6_noAl

hpk6_Al

1kHz_noAl(6)

1kHz_Al(38)

Output Charge (mC/cm )2

Rela

tive

QE (

%)

w/o Al

w/ Al

1year operation

Need Al-layer, too.Lifetime ∼ 300mC/cm2 even w/ Al layer⇒ Need effort (Vacuum level)


Lifetime: Gain

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 100 200 300 400 500 600 700 800

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.


Rectanglular PMT: SL104ch linear array MCP-PMT

Photo cathode mutli-alkaliMCP ch φ 10 µm# of MCP 2 stage

# pixel/size 1×4 / 5mm×22mmGeometrical 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


Cross-talkTime 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


Cross-talk: TTSMeasurement L.E.Discri.

C.F.Discri.

σT T S � 100ps at 1.5ns delay⇒ Improvement w/ CFD : σT T S ∼ 40ps


Summary and Future PlanSummary

Performance StudyNeed to reduce chormatic dispersion error⇒ segmented bar, GaAsP photo-cathode MCP-PMT with GaAsPphoto-cathode⇒ ∼ 4σ π/K separation @4GeVNeed to test of lifetime.Lifetime testNeed Al layer at least, it is not enough, though.Cross-talkDivide electrodes, CFD → TTS ∼ 40ps

Future PlanLifetime of MCP-PMTNeed more effort. Test of the GaAsP photo-cathode.BINP’s GaAs MCP-PMTPerformance check Lifetime test

Other issuesReadout elec., Support structure, · · ·: working now


Personal AnnouncementI have another talk on the τ -physics in thePhysics Parallel V, tommorow afternoon.Please come and listen!


Personal AnnouncementI have another talk on the τ -physics in thePhysics Parallel V, tommorow afternoon.Please come and listen!Although I don’t finish the preparation yet.


Backup


MCP-PMT Performance: Raw SignalHPK multi-alkali GaAsP


Readout elec.: TAC-ICRequirements

Time resolution � 20psby Time to Analog ConverterLow dead time ∼ 100 psLimited double overlap gateSmall size & Multi channel

Test production (by VDEC)

TAC with comparator, CFDWell work with 40MHz clock!Time resolution: ∼ 200 ps⇒ should be improved for

the next test production


GeometryMore realistic design study by simulation

Quartz, Al wall, (Al honeycomb holder)Narrow space for support structure → Maybe need more space


Documents

TOP R&D status - phys.hawaii.edusuperb/2005/slides/detector2/satoh/... · alkali is observed for GaAsP photo-cathode MCP-PMT. TDC: σTTS∼ 30ps multi-alkali 0 2000 4000 6000-20 -10