hiroyuki sekiya nnn10 dec 15 2010@toyama hiroyuki sekiya icrr, university of tokyo special thanks t....

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama 　

Hiroyuki SekiyaICRR, University of Tokyo

Special Thanks T. Abe

F. Tokanai, & T. SumiyoshiHamamatsu Photonics

Review of photo-sensor R&D for future water Cherenkov

detectorsNNN10 Dec 15 2010

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Contents/Disclaimer

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Many activities aiming for larger/lower cost/mass-production

Quick review of only below technologies◦Super Bi-Alkali /Ultra Bi-Alkali◦Hybrid Photo-Detector◦Gas Photo-Multiplier◦Micro-PMT


Do we need R&D?

R3600-05 (The 20 inch PMT) is excellent. It provided reliable detectors and actual results.

To keep the production quality of R3600-05, continues order to Hamamatsu is the best way.

We had better order 100,000 R3600-05s as soon as possible in order to get next generation water Cherenkov detectors within several years.

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Why do we R&D?

Because we want better photon sensors with lower price in short delivery date!

The key motivation is COST.◦Some strategies to reduce cost

Fewer detector with better QE Larger photo-coverage with cheaper sensors Simple structure for short time/mass production etc.

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Pessimistic conclusion

Largest sensors cannot be applied to commercial market. Hamamatsu knows…

Novel prize does not help their sales. Hamamatsu knows…

After all, R3600-05 did not bring so much benefits to Hamamatsu.

If we develop new sensors with them, cost/area may not decrease. It’s completely up to them.

However, actually, they are always willing to develop new sensors with us and they are excellent.

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Super Bi-Alkali/Ultra Bi-Alkali

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Quantum efficiency

Definition: SBA/UBA

ν: frequency of the photon R: reflection coefficientk: total absorption coefficientPν: excitation probability to vacuum levelL: average deviating distance of the excited e-

Ps: extraction probability from the surface

vacuum level

work function

Fermi level

valence band

band gap

electron affinity

γ:hν

Reflection loss Loss in the PC

Excitation efficiency

Extraction efficiency

SBA : reduction of the losses UBA : enhancement of the efficiencies

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5’’ SBA PMT is available →

So far, UBA is available only for metal package PMTs“transfer” technology is required.

◦ PC is made separately from the tube and assembled

Not cheaper at all.

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Hybrid Photo-Detector(HPD)

Hybrid car◦Ex) Engine + Motor

Hybrid photo sensor◦Ex) Photo tube + Semiconductor

Hybrid gain: Bombardment + Avalanche

TOYOTA PRIUS

Hamamatsu HPDAPD

13’’ HPD

Photo tube (cathode)

Engine

motor

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HPD -operation principle-PMT

Dynode

APD

×107

× 4500@20kV

Total hybrid gain

×105

× 30

HPD

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Concern? APD high dark current?

P.E. collection efficiencyreaches more than 95%(PMT: 70%)

20kV too high voltage?

No increase in dark current after 1000h operation at 4mARadiation hard.

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Better than PMTs

This implies HPD is not cheaper than PMT.We should not require everything to realize low cost??

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More Hybrid may reduce total cost

HPD+Electronics(A/D)+HV

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Performance of the Hybrid HPD

Analogue output

1 p.e.

2 p.e.

0 p.e.

1p.e.

2 p.e.

3 p.e.?

Digital output

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8’’ and 13’’ HPDs available in 2012

Hamamatsu will release in 2012

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Gas Photo-Multiplier(GPM) A kind of Hybrid detectorsElectron multiplication by gaseous avalanche. If combined with photocathode, very large flat-panel

detectors can be realized with much lower cost/area.A weak point → Strategy of “Do not require everything”

F. SauliMichigan University, Ann Arbor - May 23, 2002

LARGE MWPC

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GPM –operation principle-Photocathode + Micro Pattern Gas Detectors

Combination of MPGDsMulti-stage amplification

Gas avalanche

Total gain ×105

REFLECTIVE PC

TRANSMISSIVE PC

High resolution imaging Possible High QE

photocathode

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Large Area MPGDsVery active R&D and actually in use!

100cmx30cm@CERN

Mesh

Rui de OliveiraMPGD2009

Micromegas with readout Kapton-GEM foil

150cmx50cmfor T2K? TPC

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Large Area MPGDs in JapanVery active R&D and actually in use!

μ-PIC with readout LCP-GEM foil

30cmx30cmfor NEWAGE(Dark Matter Search)

31cmx28cm@Kyoto

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MPGD2011 will be held in Kobe Aug 29 – Sep 1 2011

2nd International workshop on MPGD followed by RD51 collaboration meeting

Followed by RD51 collaboration meeting (Non-EU hosts for the first time) International organizing committee: A.Cardini (INFN Cagliari), K.Desch (U.Bonn), Th Geralis (Demokritos Athens), I.Giomataris (CEA Saclay), T.Kawamoto (ICEPP Tokyo), A.Ochi (Kobe Univ), V.Polychronakos (BNL), A.Sharma (CERN), S.Uno (KEK), A.White (U.Texas Arlington), J.Wotschack (CERN), Z.Zhao (USTC China)Local organizing committee: J.Haba (KEK), H.Hamagaki (CNS), T.Kawamoto (ICEPP), A.Ochi (Kobe Univ.), H.Sekiya (ICRR), A.Sugiyama (Saga Univ.), A.Taketani (RIKEN), T.Tamagawa (RIKEN), T.Tanimori (Kyoto Univ.), S.Uno (KEK)

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Feedback Problems in photon detection

Ion and photon feedbacks

Limit the stable high gain operation Many activities to overcome the feedbacks.

◦ Gating◦ Ion defocusing by MHSP/COBRA

A.Breskin TIPP09@Tsukuba

１

５

◦ Blind reflection

A. Breskin et al.,T. Sumiyoshiet al.,

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2GEMs+μPIC with CsI PC 10cm x 10cmPossibility without HamamatsuSo far, tested with UV sensitive CsI

◦ Low Ion feedback achieved!

10cm

Sekiya et al

Anode current

PC current

Deuteron Lump

Ion Back Flow = Ic/Ia 　 < 10-3

@ gas gain 105

54mm

TRANSMISSIVE CsI PC on MgF2 window

REFLECTIVE CsI PCon Au coated LCP-GEM

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ImagingWith solid UV scintillatorsCan be applied to LAr/LXe

Star

犬

JINST 4 (2009) P11006NIM (2010) doi:10.1016/j.nima.2010.06.114

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Hamamatsu’s GPM

Bialkali PC + glass GEM(capillary plate)

Prototype for R&D

Pyrex glass GEM

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Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama 　TIPP09 in Tsukuba 2525


QE in gas is lower –The weak point-

Ne+CF4 gas: 14%（ Max ＠ 350nm)Ar+CF4 gas :12% （ Max ＠ 420nm)

In vacuum ～ 20%In Ar+CF4 ～ 12%

After evacuation, QE recovered to ~20%.

Trans-missive Photocathode

QE~12%

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Long term stabilityQE maintains almost the same value after 581

days operations.

Period (days)

Rel

ativ

e g

ain

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Strong for Magnetic fieldCompensation coil for terrestrial B free!

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Make it larger Hamamatsu established the production of large

Pyrex grass GEM

thickness 300 mm

diameter at entrance 160 mm

diameter at center 124 mm

pitch 300 mm

Made by a new production Method: Sandblasting

10cm

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By 2012, they will conclude

Towards large flat panel photo-sensor

100mm square Pyrex glass GEM compared with H8500D

These are assembled in a ceramic vessel?

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μ-PMT If we don’t require the largeness

Real low cost with real mass-production! MEMS(Micro Electro Mechanical Systems) technology

realized μ-PMT → 　 PMT? , silicon detector? No assemble, completely automated process

Glass base

Silicon base

Glass base(window)

Dynode by micro etching technology

13mm

10mm

Photo cathode(SBA)

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μ-PMTPrototype: 300 pieces on a 6’’ waferVery uniform quality20% Photo coverage possibility in future??

2x2 sample

Typical output signalof prototype

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Conclusion

There are many activities that can be applied to next generation large water Cherenkov detector.

Hybrid is also trend in photo-sensors.◦ The 20’’ PMT is still the candidate.◦ SBA technology is already taken into new photo-

sensors.◦ HPD is the most plausible next generation candidate.◦ GPM can be a dark horse. ◦ Post-next generation large sensor?

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hiroyuki sekiya nnn10 dec 15 2010@toyama hiroyuki sekiya icrr, university of tokyo special thanks t....

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