1. Development of 144 Channel Multi-Anode HPD for Belle Aerogel RICH Photon Detector Development of 144 Channel Multi-Anode HPD for Belle Aerogel RICH Photon Detector 1 I. Adachi, 2 R. Dolenec, 2 A. Petelin, 3 K. Fujita, 2 A. Gorisek, 3 K. Hara, 3 D. Hayashi, 3 T. Iijima, 3 K.Ikado, 4 H. Kawai, 5 S. Korpar, 3 Y. Kozakai, 6 P. Krizan, 4 A. Kuratani, 3 Y. Mazuka, 7 Y. Miyazawa, 1 S. Nishida, 8 I. Nishizawa, 9 S. Ogawa, 2 R. Pestotnik, 8 T. Sumiyoshi, 4 M. Tabata, 3 M. Yamaoka 1:IPNS, KEK, Tsukuba, Japan / 2:J.Stefan Institute, Ljubljana, Slovenia / 3:Dept. of Physics, Nagoya Univ., Nagoya, Japan / 4:Dept. of Physics, Chiba Univ., Chiba, Japan / 5:Faculty of Chemistry and Chemical Engineering, Univ. of Maribor, Maribor, Slovenia / 6:Faculty of Mathematics and Physics, Univ. of Ljubljana, Ljubljana, Slovenia / 7:Dept. of Physics, Tokyo Univ. of Science, Noda, Japan / 8:Dept. of Physics, Tokyo Metropolitan Univ., Hachioji, Japan / 9:Dept. of Physics, Toho Univ., Funabashi, Japan presenter: Ichiro Adachi (ichiro.adachi@kek.jp) Aerogel radiator Position sensitive PD with B=1.5Tesla Cherenkov photon 200mm n=1.05 Proximity Focusing RICH with Aerogel Radiator Developed for new particle ID device in the Belle forward region extend  /K separation capability up to 4  at 4.0GeV/c limited space operational under 1.5 Tesla magnetic field Key elements Hydrophobic aerogel with refractive index of 1.050 as a Cherenkov radiator Position sensitive photodetector with ~5x5mm 2 pixel size Electronics for read-out The present Belle detector Principle of Operation Established at Test Beam Experiments n=1.05 aerogel radiator  =14mrad Npe = 6 4  separation confirmed  4.0GeV “K”4.0GeV typical event RICH prototype counter Hamamatsu Multi-anode Flat-Panel PMT(H8500)  /K 4  separation at 4 GeV/c achieved with a prototype counter Multi-Anode Hybrid Photon Detector : Key Component High sensitivity to single photon Immune to 1.5 Tesla magnetic field Large effective area Basic requirements Hybrid (Avalanche) photon detector is our first candidate Developed with Hamamatsu Photonics Package72x72 mm 2 # of pixels12x12(6x6/chip) Pixel size5x5 mm 2 Effective area64 % HAPD specifications 1 diode chip pixelated to 6x6 channels 72mm = “bombardment” gain ~1000 x “avalanche” gain ~10 single photon signal ~10000 electrons ceramic tube Experimental Set-up and Noise Level ClearPulse 580K ClearPulse 4417 Amptek pocketMCA 150pF 100MΩ 220MΩ 222pF 10MΩ High Voltage Bias Voltage Reverse bias voltage supplied to cathode Signal extracted from anode side LED used as a light source Only 1 channel read out, Others floated Noise level check by bias voltage scan Full depletion observed at ~50V Minimum noise level ~ 280V Similar tendency for all of 4 chips Diode chips show reasonable behavior Pulse Height Spectra HAPD Response for single photon light pedestal 1 p.e. Clear signal observed pedestal 1 p.e. 2 p.e. 3 p.e. 4 p.e. 5 p.e. 6 p.e. 7 p.e. Response for multiple photon light Total gain ~7,320 S/N ~ 4.9 Chip-A ch#22HV= -8.5kV & Bias=+319V ChipAChipD ChipCChipB Target : ch22 - Bias=+340V - Gain 〜 7,360 - S/N 〜 4.8 - Ava. Gain 〜 4.8 Target : ch22 - Bias=+340V - Gain 〜 8,130 - S/N 〜 4.5 - Ava. Gain 〜 5.6 Target : ch22 - Bias=+360V - Gain 〜 8,530 - S/N 〜 4.1 - Ava. Gain 〜 5.7 Target : ch22 - Bias=+319V - Gain 〜 7,320 - S/N 〜 4.9 - Ava. Gain 〜 4.4 We can observe single p.e and S/N ratio is larger than 4.1 in all 4 chips. H.V=- 8.5kV Uniformity & X-talk in Diode Chip A BC D 1010 5 Single photon-equivalent light injected for all channels in one diode chip-A Gain Max 〜 7,700@ch16 Gain Min 〜 6,310@ch31 S/N Max 〜 6.2@ch8, 21 S/N Min 〜 4.3@ch6 Noise av 〜 1,310[e] Single p.e. can be observed for all channels (except for #5 and #10)  Gain ~ +/- 9%, S/N >~ 4.3, Noise ~1,300e Channel # Gain/noise/S-to-N ratio calculated for each channel Basic Properties for 4 Diode Chips from Our Measurements Ch17 Ch16 Ch15 Ch23 Ch22 Ch21 Ch29 Ch28 Ch27 LED off Spot@ch22 □2mm×2mm LED on LED light illuminated to ch#22 through a small spot Investigate pulse activities in neighbor channels for LED on/off Negligibly small contribution in X-talk activities Ch17 Ch16 Ch15 Ch23 Ch22 Ch21 Ch29 Ch28 Ch27 ConclusionsReferences  We have developed a 144 channel multi-anode hybrid photon detector for a photo-sensor in the Belle aerogel RICH counter.  New test sample delivered around the end of 2006 from HPK. Fundamental properties have been examined in our test bench.  Clear signal from single photon light has been observed, and total gain of ~7,500 was obtained.  Reasonable uniformity of gain and signal-to-noise responses found  X-talk seems to be small  The next prototype having higher avalanche gain will be delivered soon. 1.T.Iijima et al., NIM A543(2001)321. 2.T.Matsumoto et al., NIM A521(2004)367. 3.T.Iijima, S.Korpar et al., NIM A548(2005)383. 4.I.Adachi et al., NIM A553(2005)146. 5.P.Krizan et al., NIM A565(2006)457. QE = 24% from HPK measurement Avalanche gain calculated by total gain from our measurement and bombardment gain from HPK sheet Delivered at the end of 2006 after technical improvements in HPK production process except for noisy channels of #5 & #10