Review of photo-sensor R&D for future water Cherenkov detectors NNN10 Dec

Transcription

1 Review of photo-sensor R&D for future water Cherenkov detectors NNN10 Dec Hiroyuki Sekiya ICRR, University of Tokyo Special Thanks T. Abe F. Tokanai, & T. Sumiyoshi Hamamatsu Photonics 1

2 Contents/Disclaimer 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 2

3 Do we need R&D? R (The 20 inch PMT) is excellent. It provided reliable detectors and actual results. To keep the production quality of R , continues order to Hamamatsu is the best way. We had better order 100,000 R s as soon as possible in order to get next generation water Cherenkov detectors within several years.

4 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.

5 Pessimistic conclusion Largest sensors cannot be applied to commercial market. Hamamatsu knows Novel prize does not help their sales. Hamamatsu knows After all, R 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.

6 Super Bi-Alkali/Ultra Bi-Alkali

7 Definition: SBA/UBA Quantum efficiency γ:hν band gap valence band vacuum level electron affinity work function Fermi level Reflection loss Excitation efficiency Loss in the PC Extraction efficiency 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 SBA : reduction of the losses UBA : enhancement of the efficiencies

8 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.

9 Hybrid Photo-Detector(HPD) Hybrid car Ex) Engine + Motor Hybrid photo sensor Ex) Photo tube + Semiconductor Hybrid gain: Bombardment + Avalanche 13 HPD Engine motor TOYOTA PRIUS Photo tube (cathode) APD Hamamatsu HPD

10 HPD -operation principle- PMT Dynode 10 7 HPD APD 4500@20kV 30 Total hybrid gain 10 5

11 Concern? 20kV too high voltage? APD high dark current? P.E. collection efficiency reaches more than 95% (PMT: 70%) No increase in dark current after 1000h operation at 4mA Radiation hard.

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

13 More Hybrid may reduce total cost HPD+Electronics(A/D)+HV

14 Performance of the Hybrid HPD Analogue output Digital output 1 p.e. 0 p.e. 1p.e. 2 p.e. 2 p.e. 3 p.e.?

15 8 and 13 HPDs available in 2012 Hamamatsu will release in 2012

16 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

17 GPM operation principle- Photocathode + Micro Pattern Gas Detectors TRANSMISSIVE PC photocathode Gas avalanche REFLECTIVE PC Combination of MPGDs Multi-stage amplification Total gain 10 5 High resolution imaging Possible High QE

18 Large Area MPGDs Very active R&D and actually in use! Rui de Oliveira MPGD2009 Micromegas with readout Kapton-GEM foil 150cmx50cm for T2K? TPC Mesh

19 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)

20 MPGD2011 will be held in Kobe Aug 29 Sep nd 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)

21 Feedback Problems in photon detection A.Breskin Ion and photon feedbacks Limit the stable high gain operation Many activities to overcome the feedbacks. Gating Ion defocusing by MHSP/COBRA Blind reflection 5 A. Breskin et al., T. Sumiyoshi et al., 1

22 2GEMs+μPIC with CsI PC Sekiya et al 10cm x 10cm Possibility without Hamamatsu So far, tested with UV sensitive CsI Low Ion feedback achieved! Ion Back Flow = Ic/Ia < gas gain 10 5 Deuteron Lump TRANSMISSIVE CsI PC on MgF2 window 54mm REFLECTIVE CsI PC on Au coated LCP-GEM PC current Anode current 10cm

23 Imaging JINST 4 (2009) P11006 NIM (2010) doi: /j.nima With solid UV scintillators Can be applied to LAr/LXe Star 犬

24 Hamamatsu s GPM Bialkali PC + glass GEM(capillary plate) Prototype for R&D Pyrex glass GEM

25 TIPP09 in Tsukuba 25

26 QE in gas is lower The weak point- Trans-missive Photocathode QE~12% After evacuation, QE recovered to ~20%. Ne+CF 4 gas: 14% (Max@350nm) Ar+CF 4 gas :12% (Max@420nm) In vacuum ~20% In Ar+CF4 ~12%

27 Relative gain Long term stability QE maintains almost the same value after 581 days operations. Period (days)

28 Strong for Magnetic field Compensation coil for terrestrial B free!

29 Make it larger Hamamatsu established the production of large Pyrex grass GEM 10cm thickness diameter at entrance diameter at center pitch 300 mm 160 mm 124 mm 300 mm Made by a new production Method: Sandblasting

30 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?

31 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 Photo cathode(sba) Glass base (window) Silicon base Dynode by micro etching technology 7mm Glass base 5mm

32 μ-pmt Prototype: 300 pieces on a 6 wafer Very uniform quality 20% Photo coverage possibility in future?? Typical output signal of prototype 2x2 sample

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