R & D for Aerogel RICH · 2008. 3. 27. · 1st Achievement Proto Collab. Meeting 16 Snacks & drinks exhausted …. 1st Cherenkov Image Proto Collab. Meeting 17 Clear image observed

R & D for Aerogel RICH

Ichiro AdachiKEKProto-Collaboration MeetingMarch 20, 2008

1

Proto Collab. Meeting

Proto Collab. Meeting 2

Clear image observed !About 3:00 AM TODAY

1st Cherenkov Image detectedby 3 hybrid avalanche photon detectors from a beam test

Outline

• Introduction

• Proximity focusing RICH with aerogel radiator

• Aerogel

• Photon detector

• Schedule & cost

• Summary

3Proto Collab. Meeting

Collaborating Institutes

• KEK• Nagoya Univ.• Chiba Univ.• Josef Stefan Institute• Tokyo Metropolitan Univ.• Univ. of Maribor• Univ. of Ljubljana• Toho Univ.

• And you ?


PID upgrade for the endcap

Aerogel RICH

Endcap ACC

5

At present no high momentum PID at the endcap regionDedicated to flavor tagging up to ~1.5 GeV/c

More uniform material in front of ECL

Target: More than 4 σ π/K separation at 4.0 GeV/c


• Requirements▫ Compact ~250 mm space▫ Operational in 1.5 T magnetic field

• Key components▫ Photon detector

Sensitive to single photonPosition resolution ~5 mm

▫ Transparent aerogel▫ Readout electronics

Proximity focusing aerogel RICH

Aerogel radiator

Position sensitive devicewith B=1.5Tesla

Cherenkov

photon

200mm

n=1.05

6

Proximity focusing type

- n = 1.05 - θc(π) ~ 308 mrad @ 4 GeV/c- θc(π)– θc(K) ~ 23 mrad- pion threshold 0.44 GeV/c- kaon threshold 1.54 GeV/c

− σc = 14 mrad with Npe = 6

4 σ separation at 4 GeV/c



Principle of Operation Established

• R&D project started since 2000• Performance tested at the beam experiment in 2002

n=1.05 aerogel radiator

RICH prototype counter

Hamamatsu Multi-anode Flat-Panel PMT(H8500)

σ =14mrad Npe = 6

π/K 4σ separation at 4 GeV/c achieved

need more photoelectrons for further improvement as well as for further robustness

results from 3.0GeV/c π beam


New Concept to Improve PerformanceCherenkov photons are “focused” onto the photon detector plan.New idea has been validated in test beam (3.0GeV/c π beam)

n1 n2

Focusing by 2cm+2cm aerogel (n1:1.047, n2:1.057)

4cm-thick single index aerogel

σθ(1p.e.) = 22 mradNpe ~ 10.6σθ(track) = 6.9 mrad

σθ(1p.e.) = 14.4 mradNpe ~ 9.6σθ(track) = 4.8 mrad

NIM A548(2005)383


Multiple Radiator Configuration

1.0451.050

1.0551.062

# of photoelectrons

▲：single index layer

●：multiple layer

1st

▲：single index layer

●：multiple layer

single photon resolution resolution per track

2nd

3rd

4th

2nd

3rd

4th

1st

σ(track) = 4.2 mradobtained

We have succeeded in getting more Npe with keeping single photon uncertainty ~constant

|θ(π)-θ(Κ)|/σ(track) ~5.5σ separation achieved for 4 GeV/c with Npe = 9.1


Aerogel Radiator Improvements

• Transparency for index ~ 1.04-1.06 samples almost doubled• Crack-free sample for 150x150x20mm3

▫ Collaboration with Matsushita

◆2005▲2004■Before 2003

Transmission: T= T0 exp(-d/Λ(λ))Λ(λ): transmission lengthd: sample thickness

Transmission length at λ = 400nmconfirmed in a test beam

2005 sample

2001 sample

110x110x20mm3 150x150x20mm3

n =1.050

n~1.050

Photon Detector

• R&D results shown were obtained with multi-anode PMTs which does not operate in a magnetic field.

• Some photon detector candidates have been tested.


Hybrid Avalanche

Photon Detector

MCP-PMTGeiger mode

APD

Advantage Good S/NExcellent timing

resolutionStable

No HV required

Issues & RemarksMore test needed

StabilitySmall pore size

Lifetime

Noise rateRadiation damage

• Project with HPK started several years ago• Technical difficulties in fabrication process are being

overcome

Hybrid Avalanche Photon Detector (HAPD)

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Pixel APD

(Avalanche photo diode)

MultiAlkaliphotocathode

Photon

Bias(+)

4 avalanche diodes

HV-8.5kV


Bias=+343V , H.V=-8.5kV

HAPD test at bench

13

1[p.e]pedestal

Clear single photon peak observed

Total gain ~ 5x104 S/N = 8-15

Single Photon


Reasonable response for single photon level light

0.4mm step scan

Position scan test

• ASIC chip readout▫ Several iterations have been done to improve performance▫ 4th version connected to HAPDs and read-out done▫ Next version has been delivered

HAPD ASIC readout electronics

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HAPD

Readout boards for ASIC chips

18ch/chip


Beam test going on now

• We are just carrying out a test beam experiment at Fuji from March 17.


Photon detector setup is 6 HAPDs arranged as 2x3 Matrix3 HAPDs at this moment

Tracking is done by two MWPCs

1st Achievement


Snacks & drinks exhausted ….

1st Cherenkov Image


Clear image observed !!Reasonably small BG

Aerogel with n=1.045HV = 6000 V

Not ring but “smile”

We are installing 3 more HAPDs now


Micro Channel Plate PMT

• Micro Channel Plate (MCP) PMT▫ Basic study of Burl 85011 MCP-PMT has been

made

Need to enlarge active area and make pore size smaller (~10μm) for 1.5 Tesla operation

Excellent time resolution

Open up new possibility:Use MCP-PMT not only for image photosensor but also for time-of-flight counter


MCP Time-of-Flight Capability (1)

• Test beam setup done in 2005▫ Time information from two sources of Cherenkov photons

From MCP window (“window photon”)From aerogel radiator(“ring photon”)

window photon

ring photon


MCP Time-of-Flight Capability (2)

Read 13 channels

1. Ring Photon

1. σ = 50 ps is obtained for single photon, where 47 psis expected

2. ~20 ps could be possible for full ring of 10 p.e.

2. Window Photon 1. σ = 37 ps is obtained, where 35 ps is expected

2. 4.8 σ π/p separation at 2.0 GeV/c demonstrated

Distance between start counter and MCP is 650mm

• Advantage in using G-mode APD▫ Si-PM or MPPC▫ Low voltage around 10-100 V▫ High gain of ~105

▫ OK in magnetic field▫ High sensitivity

• Issues▫ High dark noise ~200-1000kHz

Pulse height ~ single photon▫ Radiation damage

neutron, proton

Geiger-mode APD

21

Good candidate

050U

100U

025U


scintillation counter

MWPC telescope

2.5cm aerogel n=1.045

multianode PMTsarray 2x6

SiPMsx6

Cosmic test at Ljubljana22

Cherenkov photon observed


Cherenkov photons observed in the expected time intervals-> High noise rate can be managable by providing O(ns) gate signal

+1 ns-2 ns 0 ns-1 ns

+5 ns+4 ns+3 ns+2 ns

-3 ns-4 ns-5 ns-6 ns

SiPM: Cherenkov angle distributions for 1ns time windows


Summary of Photon Detector Options

option status issue

HAPDMore samples coming

Good results from bench test with ASIC

Need more testTest in a beam

Stability

MCP-PMTTested in a beam and

understoodTOF capability shown

10 micron pore neededLifetime

G-APD First results from cosmic OK

Radiation hardnessNeed gate signal

We would like to propose one candidate this autumn


Other Activities

• Junction region between the barrel & the endcap▫ May need to put a mirror▫ Cover the dead region▫ Technical issues has to be cleared

• Geant MC studies▫ See Rok san’s talk in G4 session


mirror

Aerogel RICH Schedule

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2008 2009 2010 2011 2012Photon detector evaluation Photon detector production

ASIC readout R&D ASIC production

Aerogel R&D Production

Assembly

Module installationMechanical structure design

Production

Cosmic test

Install to Belle

Photon detector choice

Beam test


Cost “guess”timation27

oku-yen

Electronics

Mechanical structure

Aerogel & others


Summary• A lot of improvements so far

Focusing radiator schemeAerogels

• Photon detector is a keyMore results will comeTechnology choice should be madeCritical path in the construction

• Many things to doTest in a magnetic fieldMirror accommodationElectronics testHV system….




Focusing Scheme: Realistic Case

• Most of tracks inclined by 20-30 degree for the endcapdevice

2cm + 2cm aerogels

θ=30°

θ=20°

θ=20°

θ=30°

Still functioning fine


Monolithic Aerogel with Multiple Layers

• Monolithic tile consisting of multiple index layers▫ Easy to handle radiator▫ May have smaller distortion due to surface effect

n=1.0508

n=1.0565

n=1.0594

Well “focused” as a unified ring. Single photon σ = 14.0 mrad

3-layer sample


Hydrophobic Radiator Tile• Our aerogel tiles posses highly hydrophobic nature• Long term stability▫ The present ACC tiles produced more than 10 years ago shows no

deterioration• Machining possible with water jet cutting device, where ultra high

pressurized water is used

Hexagonal shape can be made by cutting from square tile !

Documents

R & D for Aerogel RICH · 2008. 3. 27. · 1st Achievement Proto Collab. Meeting 16 Snacks & drinks exhausted …. 1st Cherenkov Image Proto Collab. Meeting 17 Clear image observed