Performance of 1600-pixel MPPCfor the GLD Calorimeter Readout

Jan. 30(Tue.) Korea-Japan Joint Meeting

@ Shinshu Univ.

Takashi Maeda （ Univ. of Tsukuba)

for the GLD Calorimeter Group

1600-pixel MPPC

Guard ring

Si Resistor

The Multi-Pixel Photon Counter (MPPC)…Novel photon sensor that used for GLD calorimeter readout

The Multi-Pixel Photon Counter (MPPC)

Old Sample Can package

20 improved samples in last October and 400 samples in last December.

Very compact plastic packagefor Beam Test @ DESY

4 mm

1.3 mm

3

mm

1 x 1 mm

---Improved Point---•Higher Gain•Lower Noise rate•Package becomes compact•etc…

Pulse Shape

1 p.e.

2 p.e.

Measurement of Basic Characteristics Evaluate 1600-pixel MPPC performance as a

function of Bias Voltage and Temperature– Gain, Noise rate, Cross-talk, P.D.E.

Set up

Thermostatic chamber

Blue LED MPPC

•30oC•25oC•20oC•15oC•10oC•0oC•-20oC

Gain

eA

dSGain

S : ADC Sensitivity = 0.25 pC/ADCcountA : Amp gain = 63e : electron charge = 1.6 x10-19 C

)( oBias VVe

CGain

C : Pixel CapacitanceV0: Breakdown voltage

d

Pedestal peak

1 p.e. peak

2 p.e. peak

V0 with Temperature Variation

V0 is linear to temperature V = VBias – V0(T) is sensi

tive to temperature– Most of MPPC performa

nces are affected by temperature change

Must be improvedV0/T = (56.0 ± 0.1) mV/oC

)( oBias VVe

CGain

C : Pixel CapacitanceV0: Breakdown voltage

Noise Rate Dark noise :

Avalanche amplificationby thermal electron

Noise rate is lower in lowerV( = Vbias – V0) and temperature

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

Threshold

0.5 p.e.

0.5 p.e. Threshold

1.5 p.e.Threshold

Cross-talk Probability Cross-talk :

The cross-talk to adjacent pixels is caused by photons created in an avalanche.

2 pixels fired signals in dark noises are caused by cross-talk Cross-talk probability

is not sensitive to temperature change

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

Photon Detection Efficiency (P.D.E)

Q.E. : e- h+ pair production probability for single photon injection ( Quantum Efficiency )

Geiger : Avalanche amplification probability from single p.e.

geom : Fraction of sensitive region in a sensor ( Geometrical Efficiency)

Measurement method Compare # of p.e. of MPPC with # of p.e. of PMT (Reference)

geomGeigerMPPC EQ ..

MPPC

0.5 mm Pin-holePMT

LEDWLSF

PMTPMTep

MPPCep

MPPC N

N

..

..~ 16 %

~ Detection probability for single photon injection

P.D.E. Result

6.3 % uncertainty comes from estimation of PMT’s P.D.E

~ 6.3 %

P.D.E. of PMT

Summary We are evaluating 1600-pixel MPPC characteristic for the

GLD calorimeter readout Gain, Noise rate are sufficient for our requirement Breakdown voltage is sensitive to temperature change

– Have to monitor the temperature Photon Detection Efficiency is higher than PMT

Plans Response curve (Input light-yield vs. Output signal) Evaluate Uniformity in the sensor Measure long-term stability Figure out radiation damage effect and magnetic field

stability

Back up…

Old sample results - Gain•30oC•25oC•20oC•15oC•10oC•0oC•-20oC

a = (5.67 ± 0.03) x10-2 V/oCb = 66.2 ± 0.1 V

V0=aT+b

Old sample results – Noise rate

Vbias – V0(T) [V]

•30oC•25oC•20oC•15oC•10oC•0oC•-20oC

Old sample results – Cross-talk

Cross-talk probability looks stable with temperature inVbias – V0 < 2.5V..).5.0(

.).5.1(

epRate

epRatePcrosstalk

The cross-talk to adjacent pixelsis caused by photons created inan avalanche.

Cross-talk probability ismeasured from dark noise rates :

・30℃・25℃・20℃・15℃・10℃・ 0℃・ -20℃

Vbias – V0(T) [V]

Set upGate

Generator

Delay

Voltage

source

HV

PMT

MPPC

Stage

WLSF

Green

LED

AMP *63

Signal

input

Gate

PC

Thermo-static chamber

Clock

Generator

Voltage

source

Light yeild measurement( with noise and cross-talk subtraction)

Measure light yeild of LED light pulse

Fit ADC distributon Supposed signals are do

minated by Poisson statistics

Count number of events below 0.5 p.e. threshold ( both LED on and off )

pedestal Events 　　　　　

0.5 p.e. threshold

0.5 p.e. threshold

pedestal Events 　　　　　

Calculation of Np.e.

f(0,μLED on) = f(0, μ+μnoise)

= f(0,μ) × f(0,μnoise)

f(0,μ) = f(0,μLED on) / f(0,μnoise) = e-μ

μ = -ln( f(0,μ) )

• f(n,μ) is Poisson distribution function

• μ is Expectated number of Np.e.

• f(0,μLED on), f(0,μLED off ) are probability of 0 p.e.

f(0,μnoise) = NLED off / NLED off = e-μnoise

f(0,μLED on) = NLED on / NLED on =e-μLED on

pedestal all

pedestal all

NpeMPPC / NpePMT (Npe ratio)

WLS Fiber Y-11

Reference : JLC ストリップ・ファイバー電磁カロリメータの性能研究

　　　　　　　　 Katsumi Sekiguchi March. 2003

QE of H1161GS

Mean of QE for 1 p.e.QE × relative light yeild on each wave length

∑ （ QE × relative light yeild on each wave length ）

= Mean of QE for 1 p.e. ~16.7 %

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