R & D for Aerogel RICH · 2008. 3. 27. · 1st Achievement Proto Collab. Meeting 16 Snacks & drinks...
Transcript of R & D for Aerogel RICH · 2008. 3. 27. · 1st Achievement Proto Collab. Meeting 16 Snacks & drinks...
R & D for Aerogel RICH
Ichiro AdachiKEKProto-Collaboration MeetingMarch 20, 2008
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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
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Collaborating Institutes
• KEK• Nagoya Univ.• Chiba Univ.• Josef Stefan Institute• Tokyo Metropolitan Univ.• Univ. of Maribor• Univ. of Ljubljana• Toho Univ.
• And you ?
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PID upgrade for the endcap
Aerogel RICH
Endcap ACC
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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
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• 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
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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
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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
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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
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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
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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.
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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
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Bias=+343V , H.V=-8.5kV
HAPD test at bench
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1[p.e]pedestal
Clear single photon peak observed
Total gain ~ 5x104 S/N = 8-15
Single Photon
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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
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Beam test going on now
• We are just carrying out a test beam experiment at Fuji from March 17.
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Photon detector setup is 6 HAPDs arranged as 2x3 Matrix3 HAPDs at this moment
Tracking is done by two MWPCs
1st Achievement
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Snacks & drinks exhausted ….
1st Cherenkov Image
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Clear image observed !!Reasonably small BG
Aerogel with n=1.045HV = 6000 V
Not ring but “smile”
We are installing 3 more HAPDs now
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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
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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
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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
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Good candidate
050U
100U
025U
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scintillation counter
MWPC telescope
2.5cm aerogel n=1.045
multianode PMTsarray 2x6
SiPMsx6
Cosmic test at Ljubljana22
Cherenkov photon observed
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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
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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
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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
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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
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Cost “guess”timation27
oku-yen
Electronics
Mechanical structure
Aerogel & others
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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….
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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
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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
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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 !