R & D for Aerogel RICH

Transcription

1 1 R & D for Aerogel RICH Ichiro Adachi KEK Proto-Collaboration Meeting March 20, 2008

2 2 1 st Cherenkov Image detected by 3 hybrid avalanche photon detectors from a beam test About 3:00 AM TODAY Clear image observed!

3 3 Outline Introduction Proximity focusing RICH with aerogel radiator Aerogel Photon detector Schedule & cost Summary

4 4 Collaborating Institutes KEK Nagoya Univ. Chiba Univ. Josef Stefan Institute Tokyo Metropolitan Univ. Univ. of Maribor Univ. of Ljubljana Toho Univ. And you?

5 5 PID upgrade for the endcap At present no high momentum PID at the endcap region Dedicated 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 Endcap ACC Aerogel RICH

6 6 Proximity focusing aerogel RICH Requirements Compact ~250 mm space Operational in 1.5 T magnetic field Key components Photon detector Sensitive to single photon Position resolution ~5 mm Transparent aerogel Readout electronics Proximity focusing type Aerogel radiator n=1.05 Cherenkov photon - n = θ c (π) ~ 308 GeV/c - θ c (π) θ c (K) ~ 23 mrad - pion threshold 0.44 GeV/c - kaon threshold 1.54 GeV/c σ c = 14 mrad with Npe = 6 Position sensitive device with B=1.5Tesla 200mm 4 σ separation at 4 GeV/c

7 7 Principle of Operation Established R&D project started since 2000 Performance tested at the beam experiment in 2002 RICH prototype counter results from 3.0GeV/c π beam n=1.05 aerogel radiator σ =14mrad Npe = 6 Hamamatsu Multi-anode Flat-Panel PMT(H8500) π/k 4σ separation at 4 GeV/c achieved need more photoelectrons for further improvement as well as for further robustness

8 8 New Concept to Improve Performance Cherenkov photons are focused onto the photon detector plan. New idea has been validated in test beam (3.0GeV/c π beam) 4cm-thick single index aerogel σ θ (1p.e.) = 22 mrad Npe ~ 10.6 σ θ (track) = 6.9 mrad Focusing by 2cm+2cm aerogel (n1:1.047, n2:1.057) n1 n2 σ θ (1p.e.) = 14.4 mrad Npe ~ 9.6 σ θ (track) = 4.8 mrad NIM A548(2005)383

9 9 Multiple Radiator Configuration θ(π)-θ(κ) /σ(track) ~5.5σ separation achieved for 4 GeV/c with Npe = 9.1 # of photoelectrons single photon resolution resolution per track 2nd 3rd 4th 1st 2nd 3rd 4th σ(track) = 4.2 mrad obtained 1st :single index layer :multiple layer :single index layer :multiple layer We have succeeded in getting more Npe with keeping single photon uncertainty ~constant

10 10 Aerogel Radiator Improvements Transparency for index ~ samples almost doubled Crack-free sample for 150x150x20mm 3 Collaboration with Matsushita n =1.050 Transmission: T= T0 exp(-d/λ(λ)) Λ(λ): transmission length d: sample thickness Transmission length at λ = 400nm 110x110x20mm 3 150x150x20mm 3 confirmed in a test beam 2005 sample Before sample n~1.050

11 11 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-PMT Geiger mode APD Advantage Good S/N Excellent timing resolution Stable No HV required Issues & Remarks More test needed Stability Small pore size Lifetime Noise rate Radiation damage

12 12 Hybrid Avalanche Photon Detector (HAPD) Project with HPK started several years ago Technical difficulties in fabrication process are being overcome MultiAlkali photocathode Photon HV -8.5kV 4 avalanche diodes Bias(+) Pixel APD (Avalanche photo diode)

13 13 HAPD test at bench Bias=+343V, H.V=-8.5kV Single Photon pedestal 1[p.e] Clear single photon peak observed Total gain ~ 5x10 4 S/N = 8-15 Position scan test 0.4mm step scan Reasonable response for single photon level light

14 14 HAPD ASIC readout electronics ASIC chip readout Several iterations have been done to improve performance 4 th version connected to HAPDs and read-out done Next version has been delivered HAPD Readout boards for ASIC chips 18ch/chip

15 15 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 Matrix 3 HAPDs at this moment Tracking is done by two MWPCs

16 16 1 st Achievement Snacks & drinks exhausted.

17 17 1 st Cherenkov Image Clear image observed!! Reasonably small BG Not ring but smile Aerogel with n=1.045 HV = 6000 V We are installing 3 more HAPDs now

18 18 Micro Channel Plate PMT Micro Channel Plate (MCP) PMT Basic study of Burl 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-offlight counter

19 19 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 ) ring photon window photon

20 20 MCP Time-of-Flight Capability (2) 1. Ring Photon 1. σ = 50 ps is obtained for single photon, where 47 ps is expected 2. ~20 ps could be possible for full ring of 10 p.e. Read 13 channels 2. Window Photon 1. σ = 37 ps is obtained, where 35 ps is expected σ π/p separation at 2.0 GeV/c demonstrated Distance between start counter and MCP is 650mm

21 21 Geiger-mode APD Advantage in using G-mode APD Si-PM or MPPC Low voltage around V High gain of ~10 5 OK in magnetic field High sensitivity Issues High dark noise ~ kHz Pulse height ~ single photon Radiation damage neutron, proton Good candidate 100U 050U 025 U

22 Cosmic test at Ljubljana scintillation counter 22 MWPC telescope Cherenkov photon observed 2.5cm aerogel n=1.045 multianode PMTs array 2x6 SiPMs x6

23 23 SiPM: Cherenkov angle distributions for 1ns time windows -6 ns -5 ns -4 ns -3 ns -2 ns -1 ns 0 ns +1 ns +2 ns +3 ns +4 ns +5 ns Cherenkov photons observed in the expected time intervals -> High noise rate can be managable by providing O(ns) gate signal

24 24 Summary of Photon Detector Options option status issue HAPD MCP-PMT G-APD More samples coming Good results from bench test with ASIC Tested in a beam and understood TOF capability shown First results from cosmic OK Need more test Test in a beam Stability 10 micron pore needed Lifetime Radiation hardness Need gate signal We would like to propose one candidate this autumn

25 25 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

26 26 Aerogel RICH Schedule Photon detector choice Photon detector evaluation Photon detector production Cosmic test ASIC readout R&D Aerogel R&D ASIC production Assembly Production Install to Belle Mechanical structure design Module installation Production Beam test

27 Cost guess timation 27 oku-yen Electronics Mechanical structure Aerogel & others

28 28 Summary A lot of improvements so far Focusing radiator scheme Aerogels Photon detector is a key More results will come Technology choice should be made Critical path in the construction Many things to do Test in a magnetic field Mirror accommodation Electronics test HV system.

29 29

30 30 Focusing Scheme: Realistic Case Most of tracks inclined by degree for the endcap device 2cm + 2cm aerogels θ=30 θ=20 θ=20 Still functioning fine θ=30

31 31 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= n= n= layer sample Well focused as a unified ring. Single photon σ = 14.0 mrad

32 32 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!