Development and Study of the Multi Pixel Photon Counter Satoru - - PowerPoint PPT Presentation

Development and Study of the Multi Pixel Photon Counter

Satoru Uozumi (Shinshu University, Japan) for the KEK Detector Technology Project / Photon Sensor Group Vienna Conference on Instrumentation 2007, Feb 19-24 , 2007

• 1. Introduction
• 2. Fundamental Performance
• 3. Application to High Energy Physics
• 4. Summary

KEK Detector Technology Project Photon Sensor Group

(http://rd.kek.jp/) (KEK, Kobe, Kyoto, Nagoya, Nara-WU, NDA, Niigata, Shinshu, Tokyo/ICEPP, Tsukuba)

• S. Gomi, H. Hano,T. Iijima, S. Itoh, K. Kawagoe, S. H. Kim,
• T. Kubota, T. Maeda, T. Matsumura, Y. Mazuka,
• K. Miyabayashi, T. Murakami, T. Nakadaira, T. Nakaya,
• H. Otono, E. Sano, T. Shinkawa, Y. Sudo, T. Takeshita,
• M. Taguchi, T. Tsubokawa, S. Uozumi, M. Yamaoka,
• H. Yamazaki, M. Yokoyama, K. Yoshimura, T. Yoshioka

And special thanks to Hamamatsu photonics K.K.

substrate p+ p- p+ n+ Si Resistor

Vbias

1 mm Substrate

The Multi Pixel Photon Counter (MPPC)

• A silicon avalanche photo-diode with multi-pixel structure -

Guard ring n-

• Each pixel works as a Geiger-mode APD,
• One pixel can count only one photon.

need multi - pixel structure for photon counting

• Electric charges from all the fired pixels are summed up

and read out as a signal.

• There are 4 different types available:

1600 pixel 400 pixel

50µm

~ 0.25 25 µm 1600 ~ 0.5 50 µm 400 ~ 0.65 100 µm 1x1 mm2 100 Geometrical eff. Pixel size Sensor size # of pixels

MPPC signal (ADC counts)

100 200 300 400 500 600

Entries

0.2 0.4 0.6 0.8 1

Excellent Photon Counting Ability

0,1,2,3,4,5,6,7, . . photoelectrons ! 1 photoelectron 2 photoelectrons 1600 pixel 1600 pixel

Unknown decent Robustness Not expensive Expensive Cost fast fast Response

0.2 (1600pix.) ~ 0.5 (100pix.)

0.1 ~ 0.2 Photon Detection Eff. Determined by # of pixels Good Dynamic range Great Yes Photon counting ~ 80 V ~ 1000 V Bias voltage 105~106 ~106 Gain 1 pixel noise exist (order of 100 - 500 kHz) Quiet Noise (fake signal by thermions) Unknown Good Long-term Stability Insensitive Sensitive B field Compact Small Size MPPC Photomultiplier

The MPPC has lots of advantages

Fundamental performance

• Gain
• Dark Noise Rate
• Inter-pixel Cross-talk
• Photon Detection Efficiency
• Uniformity in a pixel

68.6 69 69.4 6 10 14 18 22 Bias Voltage (V) Gain (x10 )

100 pixel

5

69.2 69.6 70 70.4 70.8 4 6 8 10 12 14 Bias Voltage (V) Gain (x10 )

400 pixel

5

Bias voltage [V]

74 75 76 77 78 79 80 81

]

5

Gain [ x10

1 2 3 4 5 6 7 8 9

• 30oC
• 25oC
• 20oC
• 15oC
• 10oC
• 0oC
• -20oC

1600 pixel Gain = 106 – C … Pixel capacity – V0 … Breakdown voltage Over-voltage Gain =106

Fundamental Performance - Gain

• 25oC
• 20oC
• 15oC
• V0

temperature (ΔV0/ΔT ~ 50 mV/Co)

• Larger pixel size results in larger gain.
• 25oC
• 20oC
• 15oC

Breakdown voltage (V)

72 73 74 75

Number of samples

20 40 60

Pixel capacity (pC)

0.02 0.022 0.024 0.026

Number of samples

20 40 60

Variation of V0 and C over 750 MPPCs

Variation ~ 0.45 V

(Measured at 15oC)

Variation < 4%

• ~750 pieces of 1600 pixel MPPCs have been tested.
• Device-by-device variation is less than a few %.

No need for further selection or categorization on massive use ! Just need a small tuning of operation voltages.

0.2 0.6 1 1.4 100 200 300 400 500 Vbias - V0 (V) Noise Rate (kHz)

100 pixel

0.5 1 1.5 2 2.5 200 400 600 Vbias - V0 (V) Noise Rate (kHz)

400 pixel

(V)

• V

bias

V

1.5 2 2.5 3 3.5 4 4.5 5

Noise Rate (kHz)

100 200 300 400

Fundamental Performance – Dark Noise Rate

• The dark noise is caused

by thermal electrons.

• Its rate depends on both
• ver-voltage and temperature.
• More number of pixels

smaller active area fewer noise rate

1600 pixel

• 25 oC
• 20 oC
• 15 oC

300 kHz 300 kHz 300 kHz

• 30 oC
• 25 oC
• 20 oC
• 15 oC
• 10 oC
• 0 oC
• -20 oC

Fundamental Performance

• Inter-pixel Cross-talk -
• Inter-pixel cross-talk is caused by

a photon created in an avalanche

• Probability of the cross-talk has been

measured using dark noise rates:

(V)

• V

bias

V

1.5 2 2.5 3 3.5 4 4.5 5

Cross-talk probability

0.1 0.2 0.3

• 30 oC
• 25 oC
• 20 oC
• 15 oC
• 10 oC
• 0 oC
• -20 oC

1600 pixel

0.5 1 1.5 2 2.5 0.1 0.2 0.3 0.4 0.5 400 pixel Vbias - V0 (V) Cross-talk probability 0.2 0.6 1 1.4 0.1 0.2 0.3 0.4 0.5 Vbias - V0 (V) Cross-talk probability

100 pixel

• Cross-talk probability is affected by
• ver-voltage, but not affected by

temperature.

• 25 oC
• 20 oC
• 15 oC
• 25 oC
• 20 oC
• 15 oC

Fundamental Performance

• Photon Detection Efficiency (P.D.E) -
• Q.E. (~ 0.9) … Quantum Efficiency
• εGeiger (~ up to 0.9 , depends on bias voltage)

… Probability to cause avalanche

• εgeom

(0.25 ~ 0.65 , depends on pixel size) … Fraction of sensitive region in a sensor Measurement of relative P.D.E.

• Inject same light pulse into both the MPPC and the PMT,

and compare light yield measured by both: MPPC hole

PMT

LED

(λ=450~550nm)

~15 %

0.2 0.6 1 1.4 0.6 1 1.4 1.8 2.2 Vbias - V0 (V) Relative PDE

100 pixel

0.5 1 1.5 2 2.5 0.6 1 1.4 1.8 2.2 Vbias - V0 (V) Relative PDE

400 pixel

1 2 1

Fundamental Performance – Photon Detection Efficiency -

• PDE of the MPPC is x1~2 of the PMT !
• Larger pixel size

less dead space larger PDE

• The PDE also depends on over-voltage,

and slightly affected by temperature change.

• 25oC
• 20oC
• 15oC
• 25oC
• 20oC
• 15oC

2 2.5 3 3.5 4 4.5 5 5.5 0.2 0.4 0.6 0.8 1 1.2 1.4

Vbias - V0 (V) PDE ratio (= MPPC/PMT)

1600 pixel

1 2

One pixel y-point (2µm pitch) x-point (2µm pitch) x-point (1µm pitch) y-point (1µm pitch) Gain (x 105) Sensitivity (arbitrary)

Laser Scan in One Pixel

1600 pixel Sensitivity 1600 pixel Gain

• Pin-point scan has been done using YAG laser

(λ = 532 nm) with spot size ~ 1 µm.

• Variation of photon sensitivity and gain in one pixel

are evaluated.

• Observed variation is 2 ~ 5 % in a sensitive area

for the 100 / 400 / 1600 pixel MPPCs. 1600 pixel Microscopic view

Variation ~ 3 %

Practical Applications

EM-Scintillator-layer model

particles

T-Layer X-Layer Z-Layer

MPC R/O with WLSF MPC R/O with WLSF MPC R/O with WLSF absorber plate

Application to High Energy Physics

• Calorimeter for linear collider experiment -

Light yield ~ 21 p.e. Light yield ~ 13 p.e.

Direct readout WLS fiber readout Light yield of scintillator strip (1 x 4.5 x 0.2 cm) for beta-ray

MPPC MPPC

• The MPPC is feasible for strip-type

scintillator calorimeter. (size,cost, performance…)

• Dynamic range is the key issue.
• First scintillator-ECAL beam test

will start in next week at DESY !

Light yield (ADC counts)

Application to High Energy Physics

• T2K near detectors -

OffAxis detector OnAxis detector

• Need to read out large number of

signals from WLS fibers in limited space

• Used in 0.2 Tesla magnetic field
• The MPPC is the perfect solution !
• Belle Ring Imaging Cerenkov Detector -

Scintillator + WLS fiber With MPPC readout Aerogel radiators

• Capture Cerenkov ring image for particle ID
• For the ring imaging,
• Sufficient photon detection efficiency
• Position resolution (~5 mm)

are required for photon sensor.

• MPPC is a powerful candidate for this purpose,
• Larger sensor area (~3x3 mm2) is desired

in future development.

The MPPC is still evolving …

• Mar. 2005
• 100/400 pixels
• First sample

from Hamamatsu

• Jan. 2006
• 100/400/1600

pixels

• Larger PDE
• More pixels

2006-2007

• 100/400/1600

pixels commercialized

• Improved Gain

and dark noise

• Tests of

massive use

Near future

• Improved

performance

• Larger sensor area
• More pixels

?

Stay tuned for future development !

Summary

• The MPPC is a promising photon sensor which has many

remarkable features.

– High gain, compact size, low-cost, excellent P.D.E., etc ….

• Extensive R&D of the MPPC is ongoing in KEK DTP group

collaborating with Hamamatsu photonics.

– Study and improvement of basic properties … underway – Evaluation of variation over many samples … underway – Study radiation hardness (for γ-ray, neutron) … just started – Evaluate robustness and long-term stability … start soon – Test magnetic-field tolerance … near future

• Tests for actual use at several high energy physics

experiments are also underway.

• Applications in various other fields are being explored.

– Positron Emission Tomography, etc…

• The improvement of the performance will be continued

toward the “Perfect Photon Sensor” !

Novel Photon Detector Workshop Novel Photon Detector Workshop June June-

• 2007 Kobe, Japan

2007 Kobe, Japan

The KEK Detector Technology Project group will host an international workshop for the future photon sensors. Check the KEKDTP web site: http://rd.kek.jp/ Contact : Takeshi.Nakadaira@kek.jp

Backups

Application to Other Fields

Positron Emission Tomography (PET) … a powerful method to detect cancer activity.

• Capture gamma pair and identify position of the cancer.
• Spatial resolution is greatly improved by

finer granularity (~1 mm of crystal block size).

• MPPC is ideal to read out each individual crystal blocks.

25 % 50 % 65 %

Photon Detection Efficiency

50 mV / oC

Temperature dependence (ΔV0/ΔT)

1 x 1 mm2 Sensor size 100 270 400 Noise Rate (kHz) 2.75 7.5 24.0 Gain (x 105) 77 10 V 70 10 V Nominal Bias Volt. 1600 400 100 Number of pixels

• Hamamatsu photonics is starting to deliver

the MPPC.

• See following page for more information:

http://www.hamamatsu.com/news/2006/2006_1 0_26.html

(Numbers from HPK catalog)

MPPCs on sale