Study of the MPPC performance- R&D status for the GLD calorimeter readout –

http://ppwww.phys.sci.kobe-u.ac.jp/~kawagoe/gldcal/index.php?MPPC

Nov 6-10 2006

International Linear Collider Workshop Valencia

Satoru Uozumi

Shinshu University, Japan

for the GLD Calorimeter group

and KEK Detector Technology Project / Photon Sensor Group

• High Gain (105~106)• Good Photon Detection Efficiency (25~65%)• Compact (package size ~ a few mm)• Low Cost • Magnetic-field tolerant• High dark noise

(order of 100-1000 kHz)• Response against input light yield is non-linear

~ 1 mm

Depletion region ~ 2 m

Substrate

substrate p+

p-

Guard ring n-

Al conductorp+ n+

Si Resistor Vbias

The Multi Pixel Photon Counter (MPPC)- A novel semiconductor photon sensor -

The MPPC is a still developing, but promising device !

The MPPC is drastically evolving …

Mar. 2005●100/400 pixels●First sample from Hamamatsu

Jan. 2006●100/400/1600 pixels●Smaller pixel size results in more number of pixels

Oct. 2006●100/400/1600 pixels commercialized●Improved Gain and dark noise

Sometime in future●Larger sensor area●More number of pixels●And perhaps more…

?

4 mm

1 x 1 mm

1.3 mm

Side

3

mm

The New MPPC Sample• Latest 1600 pixel MPPC • 20 samples arrived in October.• Very compact plastic package

suitable for attaching to scintillator strips.

(this package is customized for our ECAL module, and not going to be commercialized)

• 500 more for ECAL beam test will be arrived in this month.

Front

MPPC

Scintillator strip

WLS fiber

Side view

Old 1600pixel sample

New 1600 pixel sample Excellent photon counting ability

0,1,2,3,4,5,6,7, . . . Photoelectrons !

~ 25

m

Performance of the

latest 1600 pixel MPPC

• Gain, Noise Rate, Cross-Talk

– Device-by-device variation

– Temperature dependence

• All results are yet preliminary

Gain = C (Vbias

-V0) / e

C : Pixel capacityV0 : Breakdown voltage

Variation of the Gain over 20 samples

Good Uniformity !

Mean : 23.82 fFVariation ~ 3.1 %

20 samples@ 25 oC

Mean : 75.55 VVariation : 0.22 V

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

V0/T= (57.3 0.1) (mV/oC)

Temperature dependence of the Gain

• Breakdown voltage is linear to temperature.• Thus the temperature change affects to the

over-voltage ( = Vbias-V0(T)). eventually affects to all the MPPC properties.

Variation of the Noise Rate Cross-talk

20 samples@ 25 oC

> 0.5 p.e.

> 1.5 p.e.

● Dark counting rate with threshold of 0.5 and 1.5 photoelectron.

● Test 20 samples @ 25 oC

Temperature dependence of theNoise Rate / Cross-talk

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

• Lower temperature lower dark noise• Cross-talk is not affected by temperature change.

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

> 0.5 p.e.

KEK Detector Technology ProjectPhoton Sensor Group

(http://rd.kek.jp/)(KEK, Kobe, Kyoto, Nagoya, Nara-WU, NDA, Shins

hu, Tokyo/ICEPP, Tsukuba)

• Develop and study the MPPC with Hamamatsu• Aiming to have satisfactory performance to use at :

– GLD calorimeter– T2K near detector– Belle Aerogel Cerenkov Counter

• Provide important feedbacks to Hamamatsu for improvement of fundamental properties

News : The MPPCs are finally on catalog !Number of pixels 100 400 1600

Sensor size 1 x 1 mm2

Nominal Bias Volt. 70 10 V 77 10 V

Gain (x 105) 24.0 7.5 2.75

Noise Rate (kHz) 400 270 100Photon Detection Efficiency 65 % 50 % 25 %

Temperature dependence (V0/T) 50 mV / oC

• Hamamastu will start to deliver the MPPC in early 2007.

• See following page for more information:

http://jp.hamamatsu.com/en/hamamatsu/press/2006/2006_10_26.html

(Numbers from HPK catalog)

Summary• We now have the new 1600 pixel MPPCs for the GLD EMCAL te

st module.• Performance of the new MPPC is sufficient for EMCAL beam tes

t.–Gain (2-8)x105, Noise Rate 50-300kHz, Cross-talk prob. < 2-20%–However properties are sensitive to temperature change. Need temperature control / monitoring at practical use.

• The MPPC is being commercialized soon !

• Measure properties of 500 samples used for the scintillator-W EMCAL module (will arrive in this month).

• Practical use for the calorimeter readout at the coming beam test ( next talk )

• The MPPC R&D will be continued until we achieve the necessary performance for the GLD calorimeter readout.

– Improvement of the dynamic range (num. of pixels) is especially important!• Also need to measure non-linearity, stability, robustness to have

deeper understanding of the device.

Plans

Backups

Photon Detection Efficiency by Hamamatsu

Measurement with Microscopic Laser System

１６００ pixel MPPC

• Introduced by KEK-Detector Technology Project

• YAG Laser, = 532 nm (green)

• Pulse width ~ 2 nsec, rate ~ 8 kHz

• Spot size ~ 1 m

• Light yield ~ 0.5 p.e. (not calibrated)

• Can perform precise pinpoint scan with the well-focused laser

~25m

Laser spot

PMT MPPC

Gain ~106 105~106

Photon Detection Eff. 0.1 ~ 0.2 0.2~ 0.7

Response fast fast

Photon counting Yes Great

Bias voltage ~ 1000 V ~ 70 V

Size Small Compact

B field Sensitive Insensitive

Cost Expensive Not expensive

Dynamic range Good Determined by # of pixels

Long-term Stability Good Unknown

Robustness decent Unknown, maybe good

Noise (fake signal by thermions)

Quiet Noisy (order of 100 kHz)

The MPPC performance

The MPPC looks feasible for theGLD Calorimeter readout!

Required performance for the GLD Calorimeter

• Gain: ~ Best to have 106 , at least 105

• Dynamic range: can measure ~1000 p.e.– satisfactory to measure EM shower maximum– need > 2500 pixels

• Photon Detection Efficiency ~ 30 %– to distinguish MIP signal

• Noise rate : ~ 1 MHz (threshold = 0.5 p.e., threshold =1.5 p.e is also acceptable) • good uniformity, small cross-talk• Timing Resolution ~ 1 nsec

– Necessary for bunch ID, slow neutron separation• Sensor area: 1.5 x 1.5 mm

– suitable for 1.5 mm fiber• Should be stable against bias voltage / temperature / time

• The MPPC performance looks feasible for the GLD calorimeter readout, but still not sufficient.

• Need study and improvement of the fundamental property to achieve our goal.

• Now we are measuring performance of latest 400 / 1600 pixel MPPC prototypes provided by Hamamatsu.

• Based on its results, we provide feedback to Hamamatsu to have improved sample.

R&D Status @ GLD Calorimeter

Evaluate performance of the MPPC prototypes

Provide feedback to HPK

Improved samples from HPK

Setup

Response / Correction curves ( with small cross-talk )

Response curve

Correction curve

R-1(p;Nfired)p=0.1

R (p;Npe)p=0.1

(no cross-talk)

p=0