Photodetector forAerogel RICH
Toru Iijima
Nagoya University
特定領域科研費「質量起源」研究会
March 9, 2004
2004/3/91

Collaborators
T.Sumiyoshi, T.Matsumoto, T.Seki
 I.Adachi, K.Suzuki, S.Saitoh T.Iijima, Y.Kozakai
 H.Kawai, T.Tabata, R.Ishibashi
 S.Ogawa, Y.Uchida P.Krizan, S.Korpar, R.Pestonik, S.Fratina(Slovenia)

2004/3/9

科研費特定領域「質量起源」研究会

TMU
KEK
NagoyaChiba
Toho
Ljubljana

2

Talk Outline“Frozen smoke”…
The lightest material in solid form

Introduction
Particle ID in Belle
Why Aerogel-RICH ?
 Requirement for Photodetector
 Results w/ Flat Pannel PMT
 Development of Hybrid Photodetector (HPD/HAPD)
 Remarks
 Summary

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科研費特定領域「質量起源」研究会

3Particle ID in Belle
Physics Targets
Flavor tagging
BÆππ/ Kπ/ KK, BÆDK/ Dπ
Low momentum µ/π at Super-B

AFB in BÆKllPresent PID

Kaon Momentum Distribution
5p (GeV/c)

Two-bodyB→ππ/πK/KK

4.5
4b→c→s(tagging)

3.5
3dE/dx + TOF + ACC(threshold)Eff.(KÆK) ~90% / fake(πÆK) ~10%
Lack of high momentum PID
in the forward endcap(almost) no µ/π for PT<1.0GeV/c

2.5
21.5
10.50-1-0.8 -0.6 -0.4 -0.2 0 0.2 0.4
P vs cosTheta (charged)

0.60.81cosθUpgrade target = K/π separation for 0.7~4 GeV/c @ >4σ(similar µ/π separation for P< 1GeV/c)
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科研費特定領域「質量起源」研究会

4Possible Upgrade Plan
 BarrelÆTOP (Time-Of-Propagation) Counter 計画
公募 EndcapÆ Proximity Focusing Aerogel-RICH

Endcap-PID
Æ Aerogel-RICHBarrel PID Æ TOP

Photo detector(position sensitive, pixel size=6 mm)

PrototypeMultianode PMT
R5900-L16

Aerogel radiator(n =1.05, 20mm thick)

Quartz bar

charged track(20×100×2 cm3)

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科研費特定領域「質量起源」研究会
200 mm5

Quartz (1.47)

Less materialρ ~ 0.1-0.2 g/cm3

Compact ringbackground

Large ∆θcsmall chromatic error

Separation powerS=∆θ cσ0θc (rad.)Why Aerogel for RICH?

Aerogel (1.03)
C4F10 (1.0014)

N pe

Quartz (1.47)
C5F12 (1.24)∆θ = θ(K)-θ(π)

Single photon resolution
Optics (emission point, mirror, …)
Pixel size in photodetectionChromatic dispersion
 Quartz~5mr C5F12 (liq.)~3mr Aerogel~2mr （※）

C5F12 (1.24)

Aerogel (1.03)
C4F10 (1.0014)※ NIM A457(2001)52

Aerogel fills the gap alsoin RICH application (new trend)6
科研費特定領域「質量起源」研究会

2004/3/9

Proximity Focusing Aerogel RICH

For Belle upgrade in the forward endcap>4σ K/π for 0.7 < p < 4.5 GeV/c
Proximity focusing w/ n =1.05, 2cm.
No mirror complex
Æ suitable for collider geometryThin radiatorÆ light yield enough ?

Design values
Npe~7.5σ011mr

σ（pix）

6.4mr

σ（em）

8.6mr

σ（chr）

2.0mr
Photo detector(position sensitive, pixel size=6 mm)

Photodetection in B=1.5T w/ 5×5mm2granularity.
HPD (baseline) Aerogel radiator(n =1.05, 20mm thick)The major R&D items

charged track

Photodetection in 1.5T
Aerogel improvement

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科研費特定領域「質量起源」研究会

200 mm7

Photodetection for Aerogel RICH
− CL / λ 4

Rayleigh scattering dominates in aerogel
T = A⋅eÆ Short wave length suppressed.
Æ Detection in visible wavelength region
Æ Vacuum based device w/ bialkali/multialkali photocathode.
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科研費特定領域「質量起源」研究会

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Photodetector Requirements
Single photon counting in visible λ region with good Position sensitivity~5mm
 Q.E. x C.E.
>20%
 Magnetic field immunity 1.5 T
 Effective area
>70%++ ASIC development to readout many channels. O(105)Hybrid photodetector (HPD) MCP(micro-channel-plate) PMT
 Flat Panel PMT

Ideal (probably)
C.E.<60%
don’t work in 1.5T

No device on market satisfy the requirement
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科研費特定領域「質量起源」研究会

9Flat Panel PMT (HPK H8500)
Large effective area, 84%64ch (pixel size = 6mmx6mm)
aligned with 52.5 mm pitch

Response for Cherenkov photonEntries

140

Flat Panel PMT (H8500)
HV = 1100V

120
near cherenkov peak

10080



Still under developing…
ÆLarge variation among 16 PMTs
Q.E. : 16~25% ( @400nm )Gain : 1~6 x 106

60
40200

* for the best PMT
0250

500

750 1000 1250 1500 1750 2000

Pulse height (ADC ch)

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科研費特定領域「質量起源」研究会

10Beam Test w/ Flat Panel PMT

Demonstration of principle
4×4 array of H8500 (85% effective area)

σ0 ~14mr
Npe ~ 6~9 if normalized to the best PMT sensitivity

4σ K/π at 4GeV/c

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科研費特定領域「質量起源」研究会

11Hybrid Photodetector (HPD)pad-HPD (CERN/LHCb)

Marriage of vacuum photocathod
and silicon device technologies.

Photoelectrons are accelerated w/ 10-20KV,bombarded on Si and lose its whole energy.
Create electron-hole pair per 3.6eV loss.
Gain = 3000-5000 / pe

Sketch by T.Ypsilantis

No multiplicative process
Much less gain fluctuation for each photoelectron.

Conventional PMT

Geometry: Electrostatic / proximity focusing
Operate in B field
Sensor: PD / APD
Additional 10-100 gains

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M.Matthias et al,IEEE2003 NSS-MIC Conf.

cf) Pixel HPD @ LHCb+DEP

80mm φ photocathod window
to cover 70% of 2.6m2 total area
Electron optics
20KVÆ 5000 e- / photon
Cross focusing (x5 demagnification)
8192 pixels (62.5µmx500µm)
Æ1024 super-pixel (0.5mmx0.5mm)
LHCBPIX1 chip bump-bonded in vacuum

Cannot be used in B field.
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Our New Development
Multialkari
12x12 HPD
photocathodeProximity geometry for use in-10kV
strong B filed
15~25mm
 Large effective area
 Consider both PD/APD options
Pixel PD or APD
Package

72x72mm2

Number of pixels

12x12 (6x6/chip)

Pixel size

5x5mm2

Effective area

64%
PD

APD

Gain

2000

20000

Cd

10pF

80pF

I (leak)

10nA

30nA

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科研費特定領域「質量起源」研究会

e-14

Ptototype Test [Single Channel HPD]
TO-8 type (sensitive area = φ8mm)
 VHV = -8KV VBIAS = -80V
1p.e.
 Gain = 1500 e/photon
2p.e.
3p.e.

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科研費特定領域「質量起源」研究会

1553 φPrototype Test [3x3 HAPD]

Diode= □5mm/ch
VHV = -8KVVBIAS = 320V
Gain = 26000 e/photon
Cd = 73pF / IL = 14nA
Surface irradiation type
Larger noise than HPD
Low yield of APD?

2004/3/9１５ｍｍ

2p.e.
1p.e.

科研費特定領域「質量起源」研究会

3p.e.

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Prototype Test [3 x 3 HPD]
Photon counting test in progress

Back irradiation type
 No serious problem in production of PD
 EB gain = 2100 @ 8KV

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Status of 12x12 H(A)PD
The bulb part is made of ceramic.
 Vacuum leak test is underway.
 4x(6x6) HPD/HAPD installed in the ceramic case by atransfer technology.
 The 1st prototype coming soon.
No photocathodeIn this sample

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Development of Readout ASIC

Total #channel in the real system = 120K
Photodetector characteristics
Gain ~ 2000 (HPD) / 20000(HAPD)
Cd ~ 10pF(HPD) / 70pF(HAPD)
Leak I ~ 10nA(HPD) / 30nA (HAPD)

Small space

NeedHigh density front-end electronics
High gain w/ low noise amplifiers
Deadtime less readout scheme (pipeline)

ASIC development

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科研費特定領域「質量起源」研究会

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ASIC for HPD/HAPD ReadoutBasic parameters (Rohm 0.35µm CMOS)
Gain = 5V/pC
Shaping time = 0.15µs
VGA = 1~16
Pipeline readout w/ shift register
18 channels/chip5mW/channel



1st trial at VDEC

2004/3/9□4.93[mm]

科研費特定領域「質量起源」研究会

20Remark: New Optics in Aerogel RICH ?
Is there any way to increase L and hence improve Npe without
diminishing σ(emission) ?

Yes, probablyPreliminaryhigh index

low index

Aerogel features;
Index controllable at mixtureÆ θc can be chosen at will.

Idea: stack (more than) 2 aerogelwith different indices.
n1>n2 Æ completely separated rings(velocity measured twice).
n1<n2 Æ focusing to compensate
the increased thickness.

Aerogel radiator
low index

Photodetector

high index

Dual Aerogel RICH !?
Aerogel radiator
Studiesareinprogress.
科研費特定領域「質量起源」研究会
2004/3/9

Photodetector
21Remark: GaAsP Photocathode?
Sensitive in longer wavelength (<700nm)
Lead to less chromatic error
Aerogel is more transparent
QE as high as 40% (or more) at peakÆ compensate Npe loss due to 1/λ2 dependence.

M.Suyama et al,IEEE2003 NSS-MIC Conf.

Dream in future ?
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科研費特定領域「質量起源」研究会

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あと、もうちょっと！です。

Summary
開発の歴史

2003

良特定



HPD基盤

2002

エアロジ

ェ

ルの改

B=1.5T

Flat Panel Npe~7

Large effective area
2001

R5900 Npe~2

奨励

1997

2004/3/9



IIT
科研費特定領域「質量起源」研究会

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Backup Slides

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Limitation of RICH
Investigation by P.Glassel [ NIM A433(1999)17 ]Pmin limited by the decrease in N/Nmax
Chromatic error dominates @ Pmax
Pmax/Pmin = 4~7
Need two/three radiators to cover wide region.
Aerogel fill the gap also in RICH application.

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科研費特定領域「質量起源」研究会

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Chromatic Error in Aerogel
R.De Leo et al., NIM A457 (2001) 52

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Magneticshieldingcf) LHCb RICH

PhotonDetectors

RICH1

Three radiators to cover 1~100 GeV/c
Aerogel
RICH1: Aerogel(n=1.03) 5cm 1-10 GeV/cC4F10 (n=1.0014) 80cm 10-60 GeV/c
RICH2: CF4 (n=1.0005) 2m‐100 GeV/c
VELO exit window
Photodetection by HPD array
2.5×2.5mm granularity, total area = 2.6m2

CF4Npe~7~31~23

σ0

2.0mr

1.3mr

0.6mr

σ（pix）

0.6mr

0.6mr

0.2mr

σ（opt）

0.3mr

0.7mr

0.3mr

σ（chr）

1.6mr

0.8mr

0.4mr

10σ K/π for 10-40 GeV/c
3σ K/π for 30-90 GeV/c
2004/3/900y (cm)

C4F10C4F10Beam pipe

TrackPlane
MirrorDesign values
Aerogelrad250 mSphericalMirror

100200z (cm)

Typical events in RICH1204060-60

科研費特定領域「質量起源」研究会-40-200x (cm)20406027

Improved Aerogel by Matsuhita/KEK

Optimization for n=1.05
n=1.01~1.03 range was optimizedin the Belle construction, but notfor n=1.05
ÆCooperative research withMatsushita Co. Ltd.
Improvement in transmission length,Λ(@400nm)15mm Æ 45 mm [ n=1.05 ]Solvent
Precurser

methyl alcohol
Ædi-methyl-formamide(DMF)
Methyl-silicate-51 fromdifferent company*Novosibirsk’s one : hydrophilicTransmission length (mm)

60504030Matsushita (DMF)
Matsushita (MtOH)

20

Chiba-U. (MtOH)
Novosibirsk (PrOH)

102001 year (MtOH)
01

1.02

1.03

1.04

1.05

1.06

Refractive index

Studies are still in progress…
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1.01

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Test w/ Flat Panel PMT

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Dual Aerogel RICH

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Proximity Focusing HPD
R&D by KEK+HPK

M.Suyama et al,IEEE2003 NSS-MIC Conf.

Proximity focused structure
for operation in strong B field.
 Acceleration voltage = 8KV Avalanche diode8x8 pixels
2x2 mm2/pixelTotal gain = 4x104

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MCP-PMTElectron amplification in microchannel (φ ~10µm)
Fast/small transit time spread
Gain saturation
B field immunity
Geometrical apperture ~ 60%
500ps※ without Al film at MCP-in

Gain ~O(106) w/ 2-3 stages



R&D in progress for

1p.e

Focusing DIRC (SLAC)
TOP (Belle/ Nagoya)Photon counting In B=1.5T
w/ 6µm MCP-PMT

2p.e
3p.e

(HPK R3809-U50-11X, Nagoya R&D)
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科研費特定領域「質量起源」研究会

32HPK MCP-PMT
R&D at Nagoya

U1chtn2chemp3chveloeDr4chnde
22 (effective area)
27.5

1x4 linear-anode MCP-PMT newly developed for TOP readout.
#MCP stage

2Gain (HV)

2x106 (-3.5KV)

MCP hole dia.

10µm

Geometricalcollection eff.

50%

#pixel /size

1x4 / 5mmx22mm

Effective area/
Total area

64%

Confirmed gain > 106 and TTS = 30ps(σ)
In B=1.5T magnetic field.
※ Remaining issues: cross talk, life, deadtime etc.
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Test of 1st batch sampleLinearity (left)
 Channel-by-channel offset variation

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科研費特定領域「質量起源」研究会

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