Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Hiroyuki Sekiya ICRR, University of Tokyo

Special Thanks

T. Abe F. Tokanai, & T. Sumiyoshi

Hamamatsu Photonics

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

detectors NNN10 Dec 15 2010

1

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Contents/Disclaimer

2

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

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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.

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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.

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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.

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Super Bi-Alkali/Ultra Bi-Alkali

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Quantum efficiency

Definition: SBA/UBA

ν: frequency of the photon

R: reflection coefficient

k: total absorption coefficient

Pν: excitation probability to vacuum level

L: 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

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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.

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Hybrid Photo-Detector(HPD)

Hybrid car ◦ Ex) Engine + Motor

Hybrid photo sensor ◦ Ex) Photo tube + Semiconductor

Hybrid gain: Bombardment + Avalanche

TOYOTA PRIUS

Hamamatsu HPD APD

13’’ HPD

Photo tube

(cathode)

Engine

motor

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

HPD -operation principle- PMT

Dynode

APD

×107

× 4500@20kV

Total

hybrid gain

×105

× 30

HPD

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Concern? APD high dark current?

P.E. collection efficiency

reaches more than 95%

(PMT: 70%)

20kV too high voltage?

No increase in dark current

after 1000h operation at 4mA

Radiation hard.

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Better than PMTs

This implies HPD is not cheaper than PMT.

We should not require everything to realize low cost??

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

More Hybrid may reduce total cost

HPD+Electronics(A/D)+HV

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

8’’ and 13’’ HPDs available in 2012

Hamamatsu will release in 2012

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Gas Photo-Multiplier(GPM) A kind of Hybrid detectors

Electron 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. Sauli

Michigan University, Ann Arbor - May 23, 2002

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

GPM –operation principle- Photocathode

+ Micro Pattern Gas Detectors

Combination of MPGDs

Multi-stage amplification

Gas avalanche

Total gain ×105

REFLECTIVE PC

TRANSMISSIVE PC

High resolution imaging Possible High QE

photocathode

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Large Area MPGDs

Very active R&D and actually in use!

100cmx30cm@CERN

Mesh

Rui de Oliveira

MPGD2009

Micromegas with readout Kapton-GEM foil

150cmx50cm

for T2K? TPC

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Large Area MPGDs in Japan

Very active R&D and actually in use!

μ-PIC with readout LCP-GEM foil

30cmx30cm

for NEWAGE

(Dark Matter Search)

31cmx28cm@Kyoto

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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)

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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. Sumiyoshi

et al.,

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

2GEMs+μPIC with CsI PC

10cm x 10cm

Possibility without Hamamatsu

So 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 PC

on Au coated LCP-GEM

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Imaging

With solid UV scintillators

Can be applied to LAr/LXe

Star

犬

JINST 4 (2009) P11006

NIM (2010) doi:10.1016/j.nima.2010.06.114

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Hamamatsu’s GPM

Bialkali PC + glass GEM(capillary plate)

Prototype for R&D

Pyrex glass GEM

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama TIPP09 in Tsukuba 25

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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%

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Long term stability

QE maintains almost the same value after 581 days operations.

Period (days)

Rela

tive

gain

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

Strong for Magnetic field

Compensation coil for terrestrial B free!

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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?

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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

7mm

5mm

Photo cathode(SBA)

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

μ-PMT

Prototype:

300 pieces on a 6’’ wafer

Very uniform quality

20% Photo coverage possibility in future??

2x2 sample

Typical output signal

of prototype

Hiroyuki Sekiya NNN10 Dec 15 2010@Toyama

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 a candidate.

◦ SBA technology is already taken into new photo-sensors.

◦ HPD is the most plausible candidate.

◦ GPM can be a dark horse.

◦ Post-next generation large sensor?