Development of 144 Channel MultiAnode HPD for Belle Aerogel RICH Photon Detector 1I. Adachi, 2R. Dol

1
Development of 144 Channel Multi-Anode HPD for
Belle Aerogel RICH Photon Detector 1I. 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.
Yamaoka1IPNS, KEK, Tsukuba, Japan / 2J.Stefan
Institute, Ljubljana, Slovenia / 3Dept. of
Physics, Nagoya Univ., Nagoya, Japan / 4Dept. of
Physics, Chiba Univ., Chiba, Japan / 5Faculty
of Chemistry and Chemical Engineering, Univ. of
Maribor, Maribor, Slovenia / 6Faculty of
Mathematics and Physics, Univ. of Ljubljana,
Ljubljana, Slovenia / 7Dept. of Physics,
Tokyo Univ. of Science, Noda, Japan / 8Dept. of
Physics, Tokyo Metropolitan Univ., Hachioji,
Japan / 9Dept. of Physics, Toho Univ.,
Funabashi, Japan presenter Ichiro Adachi
(ichiro.adachi_at_kek.jp)
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
n1.05 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

100M?
HAPD
Full depletion observed at 50V
150pF
High Voltage
Hybrid (Avalanche) photon detector is our first
candidate Developed with Hamamatsu Photonics
220M?
220M?
10M?
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
ChipC
ChipB
H.V-8.5kV
Clear signal observed

• Target ch22
• Bias360V
• Gain ? 8,530
• S/N ? 4.1
• Ava. Gain ? 5.7

• Target ch22
• Bias340V
• 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
• Bias340V
• Gain ? 8,130
• S/N ? 4.5
• Ava. Gain ? 5.6

• Target ch22
• Bias319V
• Gain ? 7,320
• S/N ? 4.9
• Ava. Gain ? 4.4

5 p.e.
1 p.e.
Total gain 7,320 S/N 4.9
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 ch22
HV -8.5kV Bias319V
Uniformity X-talk in Diode Chip
Single photon-equivalent light injected for all
channels in one diode chip-A
LED light illuminated to ch22 through a small
spot Investigate pulse activities in neighbor
channels for LED on/off
GainMax?7,700_at_ch16 GainMin?6,310_at_ch31
LED on
S/NMax?6.2_at_ch8 , 21 S/NMin?4.3_at_ch6
Noise av?1,310e
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 gt
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.