4 separation confirmed Cherenkov photon “K”4.0GeV 4.0GeV Aerogel radiator n=1.05 Position sensitive PD with B=1.5Tesla 200mm Spot@ch22 □2mm×2mm LED off Ch17 Ch23 Ch29 B C Ch17 Ch23 Ch29 5 Ch16 Ch22 Ch28 A D Ch16 Ch22 Ch28 10 Ch15 Ch21 Ch27 Ch15 Ch21 Ch27 Development of 144 Channel Multi-Anode HPD for Belle Aerogel RICH Photon Detector1I. Adachi, 2R. Dolenec, 2A. Petelin, 3K. Fujita, 2A. Gorisek, 3K. Hara, 3D. Hayashi, 3T. Iijima, 3K.Ikado, 4H. Kawai, 5S. Korpar, 3Y. Kozakai, 6P. Krizan, 4A. Kuratani, 3Y. Mazuka, 7Y. Miyazawa,1S. Nishida, 8I. Nishizawa, 9S. Ogawa, 2R. Pestotnik, 8T. Sumiyoshi, 4M. Tabata, 3M. Yamaoka1: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 (firstname.lastname@example.org) 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 ~5x5mm2 pixel size • Electronics for read-out Principle of Operation Established at Test Beam Experiments RICH prototype counter n=1.05 aerogel radiator =14mrad Npe = 6 typical event Hamamatsu Multi-anode Flat-Panel PMT(H8500) The present Belle detector /K 4 separation at 4 GeV/c achieved with a prototype counter Multi-Anode Hybrid Photon Detector : Key Component Experimental Set-up and Noise Level HAPD specifications Noise level check by bias voltage scan Basic requirements • High sensitivity to single photon • Immune to 1.5 Tesla magnetic field • Large effective area 100MΩ HAPD Full depletion observed at ~50V 150pF High Voltage Hybrid (Avalanche) photon detector is our first candidate Developed with Hamamatsu Photonics 220MΩ 220MΩ 10MΩ 222pF 222pF 72mm Diode chips show reasonable behavior ClearPulse 580K ClearPulse 4417 72mm Bias Voltage Amptek pocketMCA single photon signal ~10000 electrons Reverse bias voltage supplied to cathode Signal extracted from anode side LED used as a light source Only 1 channel read out, Others floated = “bombardment” gain ~1000 x “avalanche” gain ~10 Delivered at the end of 2006 after technical improvements in HPK production process 1 diode chip pixelated to 6x6 channels Minimum noise level ~ 280V Similar tendency for all of 4 chips ceramic tube Pulse Height Spectra Basic Properties for 4 Diode Chips from Our Measurements Response for single photon light Response for multiple photon light ChipB ChipC H.V=-8.5kV Clear signal observed • Target : ch22 • Bias=+360V • Gain 〜 8,530 • S/N 〜 4.1 • Ava. Gain 〜 5.7 • Target : ch22 • Bias=+340V • Gain 〜 7,360 • S/N 〜 4.8 • Ava. Gain 〜 4.8 pedestal 3 p.e. pedestal ChipA ChipD 2 p.e. 4 p.e. • Target : ch22 • Bias=+319V • Gain 〜 7,320 • S/N 〜 4.9 • Ava. Gain 〜 4.4 • Target : ch22 • Bias=+340V • Gain 〜 8,130 • S/N 〜 4.5 • Ava. Gain 〜 5.6 5 p.e. Total gain ~7,320 S/N ~ 4.9 1 p.e. 1 p.e. 6 p.e. 7 p.e. We can observe single p.e and S/N ratio is larger than 4.1 in all 4 chips. QE = 24% from HPK measurement Avalanche gain calculated by total gain from our measurement and bombardment gain from HPK sheet Chip-A ch#22 HV= -8.5kV & Bias=+319V Uniformity & X-talk in Diode Chip Single photon-equivalent light injected for all channels in one diode chip-A LED light illuminated to ch#22 through a small spot Investigate pulse activities in neighbor channels for LED on/off GainMax〜7,700@ch16 GainMin〜6,310@ch31 LED on S/NMax〜6.2@ch8 , 21 S/NMin〜4.3@ch6 Noise av〜1,310[e] Channel # Gain/noise/S-to-N ratio calculated for each channel Negligibly small contribution in X-talk activities Single p.e. can be observed for all channels (except for #5 and #10) Gain ~ +/- 9%, S/N >~ 4.3, Noise ~1,300e except for noisy channels of #5 & #10 Conclusions References • 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. T.Iijima et al., NIM A543(2001)321. T.Matsumoto et al., NIM A521(2004)367. T.Iijima, S.Korpar et al., NIM A548(2005)383. I.Adachi et al., NIM A553(2005)146. P.Krizan et al., NIM A565(2006)457.