Performance of 1600-pixel MPPC for the GLD Calorimeter Readout

1
Performance of 1600-pixel MPPCfor the GLD
Calorimeter Readout

• Jan. 30(Tue.) Korea-Japan Joint Meeting
• _at_ Shinshu Univ.
• Takashi Maeda(Univ. of Tsukuba)
• for the GLD Calorimeter Group

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The Multi-Pixel Photon Counter (MPPC) Novel
photon sensor that used for GLD calorimeter
readout
1600-pixel MPPC
Si Resistor
Guard ring
3
The Multi-Pixel Photon Counter (MPPC)

• 20 improved samples in last October and 400
  samples in last December.
• Very compact plastic packagefor Beam Test _at_ DESY

4 mm
3 mm
1.3 mm

• Old Sample
• Can package

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

1 x 1 mm
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Pulse Shape
1 p.e. 2 p.e.
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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

Blue LED
MPPC
Thermostatic chamber
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Gain

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

Pedestal peak
d
1 p.e. peak
2 p.e. peak
S ADC Sensitivity 0.25 pC/ADCcount A
Amp gain 63 e electron charge 1.6
x10-19 C
C Pixel Capacitance V0 Breakdown voltage
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V0 with Temperature Variation

• V0 is linear to temperature
• DV VBias V0(T) is sensitive to temperature
• Most of MPPC performances are affected by
  temperature change
• Must be improved

DV0/DT (56.0 0.1) mV/oC
C Pixel Capacitance V0 Breakdown voltage
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Noise Rate

• Dark noise Avalanche amplificationby thermal
  electron

• 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

• Noise rate is lower in lower DV( Vbias V0)
  and temperature

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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

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

• Cross-talk probabilityis not sensitive to
  temperature change

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Photon Detection Efficiency (P.D.E)
Detection probability for single photon
injection

• Q.E. e- h pair production probability for
  single photon injection ( Quantum
  Efficiency )
• eGeiger Avalanche amplification probability
  from single p.e.
• egeom Fraction of sensitive region in a
  sensor ( Geometrical Efficiency)
• Measurement method
• Compare of p.e. of MPPC with of p.e. of PMT
  (Reference)

LED
WLSF
MPPC
PMT
16
0.5 mm f Pin-hole
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P.D.E. Result
6.3
P.D.E. of PMT
6.3 uncertainty comes from estimation of
PMTs P.D.E
12

• 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

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Back up
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Old sample results - Gain

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

V0aTb
a (5.67 0.03) x10-2 V/oC b 66.2 0.1 V
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Old sample results Noise rate

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

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Old sample results Cross-talk
The cross-talk to adjacent pixels is caused by
photons created in an avalanche.
Cross-talk probability ismeasured from dark
noise rates

• Cross-talk probability looks stable with
  temperature inVbias V0 lt 2.5V.

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Gate Generator
Clock Generator
Set up
PC
Gate
Signal input
AMP 63
Green LED
MPPC
WLSF
Voltage source
Voltage source
Stage
PMT
Thermo-static chamber
HV
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Light yeild measurement( with noise and
cross-talk subtraction)

• Measure light yeild of LED light pulse
• Fit ADC distributon
• Supposed signals are dominated by Poisson
  statistics
• Count number of events below 0.5 p.e. threshold (
  both LED on and off )

0.5 p.e. threshold
pedestal Events
0.5 p.e. threshold
pedestal Events
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Calculation of Np.e.

• 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

all
pedestal
pedestal
all

• f(0,µLED on) f(0, µµnoise)
• f(0,µ) f(0,µnoise)
• f(0,µ) f(0,µLED on) / f(0,µnoise) e-µ
• µ -ln( f(0,µ) )

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NpeMPPC / NpePMT (Npe ratio)
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WLS Fiber Y-11
Reference JLC???????????????????????
Katsumi Sekiguchi March. 2003
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QE of H1161GS
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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
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Response / Correction curves ( with small
cross-talk )
R (pNpe)
R-1(pNfired) p0.1
p0.1
p0
(no cross-talk)
Response curve
Correction curve