Performance of MPPC using laser system

Photon sensor workshop @ KEK2005.12.26-27

Niigata university , ILC calorimeter groupSayaka IBA, Hiroaki ONO, Paul Anthony RAMIREZ

Takahiko ITIKAWA, Hitoshi MIYATA

Contents

1. Study of Niigata university

2. New photon sensor -- MPPC --

3. Laser system and setup

4. Performance of first version MPPC1. Signal

2. Pixel signal uniformity (gain & efficiency)

3. Break down voltage

5. Development of MPPC

6. Readout from scintillator using WLS fiber

7. Summary and future plan

Fine segmentation scintillatorRead out by photon sensor

1. Study at Niigata university

Present design of GLD Calorimeter We might need smaller segmentation c

alorimeter Ex. 10x40x2mm strip type scinti

X, Z-layer strip scinti: 10x200x2mm Tile-layer: 40x40x2mmThis granularity will be checked by simulation soon

2. New photon sensor --MPPC-- MPPC :Multi Pixels Photon Counter Made by HPK and under development

Compact device Gain is 106~

Same level as PMT Don’t need other amplifier

Works with much lower voltage than PMT Suitable for wavelength shifter fiber Useful under magnetic field

PMT can’t work under magnetic field

Type of MPPC (100pixels) First version (First MPPC) Type#: 1-53-1A-11

MPPC overview

MPPC 100pixels (10x10pixels)

~85um

~100um

3. Laser system and setup

Output circuit

YAG LaserLogic readout

YAG Laser Wave length & power: 532nm (10mJ/cm2), 1064nm (20mJ/cm2) Filter : Laser intensity is down to10-8

Trigger : from Laser systemPulse width : <10nsecLaser beam minimum spot size : <2um Precision of laser position : ±2um

MPPC

MPPC

4. Performance of first version MPPC

Rise time : ~10ns, Fall time : ~500ns + tail From the ADC graph, we calculated the Charge output of 1pixel

which is ~ 2.5pc and Gain is ~1.6x107 for 100pixels MPPC

10mV

500nsec

View from oscilloscope From ADC signal

0pixel (0photon)

1pixel (1photon)

2pixel (2photon)

signal

trigger

Signal for laser 1pixel injection

Why does MPPC yield above 2pe signal from 1pixel ? Cross talk

Laser light inject other pixels avalanche electron goes to other

pixels inside semiconductor

Pulse Height

1photon mean

0photon mean

0pe1pe

From cross talk

Efficiency =# of 0 or 1photon events

# of All events

Gain =PH(ADCcount)x-0.25(pc/ADCcount)

1.6x10-19(pc)

PulseHeight = 1photon mean – 0photon mean

Measurement performance

Pixel signal uniformity in one pixel (Position dependence between two pixels) Checked efficiency between two

pixels as uniformity measurement Scanned 7points between two

pixels Wavelength : 532nm Sensor bias : 49.0V

Efficiency of more than 1photon event becomes minimum at the boundary line between 2pixels

Efficiency vs Position▲ : Efficiency of 0photon event● : Efficiency of 1photon event≧

pixel pixel

Sensor signal uniformity dependent on the pixel locations

Injected laser single photon to each pixel and got response Measurement conditions

MPPC : 100pixels Sensor bias : 49.0V Laser wavelength : 532nm, Intensity : 160 Laser hitting area is smaller than 1pixel area Measured points are 50points that are shown as gray area

~30um

~35um

Laser hitting area (smaller than 1pixel)

~85um

Measured points : 50points(Gray pixels)

Deviation of PH (RMS) : 10% Laser long term fluctuation : 5%≦

Pulse Height

1photon mean

0photon mean

Pulse height vs Pixel positionSensor bias: 49.0V

Distribution of the PH

# of pixels

Cross sectional view (Central part)

Cross section of X-axis (line-5 + line-6) and Y-axis (line-5 + line-6) which are shown in previous slide Central part of sensor

Cutting X-axis line-5▲ + line-6▲

Cutting Y-axis line-5▲ + line-6▲

X-axisline-5 +6

Y-axisline-5+6

Cross sectional view (Edge part)

X-axisline-9 +10

Y-axisline-9+10

Cutting X-axis line-9▲ + line-10▲

Cutting Y-axis line-9▲ + line-10▲

Cross section of X-axis (line-9 + line-10) and Y-axis (line-9 + line-10) Edge of sensor

We can see that pulse height level and deviation look same as previous slide

Position dependence of efficiency

Compare efficiencies between 0photon events and more than 1photon events

Edge of sensor shows low signal efficiency Central area of sensor has good efficiency

Efficiency : 0photon Sensor bias : 49.0V

Efficiency : 1photon≧Sensor bias : 49.0V

Break down voltage

MPPC 100pixel MPPC works best performance

under Geiger mode Enough laser beam incident

(saturation was occurred at best operation voltage)

If it down the voltage, some pixel become Geiger mode

48.4VLaser : same as above(saturation)

49.1VLaser : saturation

~80pe

~10pe

Sensor : First MPPC100pixels (no type#)

At 48.4V 100pixels

10pixelsGeiger mode

90pixelsAvalanche mode

Break down V = Start Geiger mode V

It is different break down voltage at each pixel !!

Efficiency : 0photon position X=8,Y=9 eff: poor

position X=5,Y=6 eff: excellent

position X=5,Y=10 eff: too bad

49.1V

49.1V49.0V

The part of 1photon appearance is difference ->Breakdown voltage is difference

Eff.

Bias(V)

Summary of first MPPC

We measured two types of Hamamatsu MPPC which are under development : 100pixels, first type

PH uniformity was 10% (RMS), while laser long term fluctuation was less than 5%

Central part of a sensor had good efficiency while edge part showed inefficiency in the light collection

Breakdown voltage Breakdown voltage = start Geiger mode voltage Sensor bias depend on Efficiency The part of 1photon appearance was difference (~100mV) at

each pixel : breakdown voltage was difference, too Best operation voltage range was delicate (~200mV)

5. Development of MPPC

1-53-1A-11 (100pixels) First MPPC(100pixels)

Best operation V

(Best operation range)

49.9V~50.3V

(<400mV)

49.0V~49.1V

(<200mV)

Gain (average value) 1.60x107 (20pixels) 1.41x107 (50pixels)

Deviation of PH for each pixel

2%

(RMS of 20pixels)

10%

(RMS of 50pixels)

Efficiency for average of all pixels

22% (50.0V, RMS of 20pixels)

59% (49.0V, RMS of 50pixels)

Deviation of efficiency for each pixel

22% (50.0V, RMS of 20pixels)

66% (49.0V, RMS of 50pixels)

Break down voltage range

<200mV (49.9V~50.0V)

at 3pixels

<200mV (49.0V~49.1V)

at 6pixels

Deviation of PH

Deviation = RMS / Mean value

Deviation of PH for each pixel : 10% 2%, better than first MPPC

Deviation: 2%

Histogram of deviation for pulse height

Deviation: 10%

Using 50pixels data Using 20pixels

7. Final summary and future plan

Laser intensity dependence For getting the best laser

intensity corresponding to 1photon injection

Measurement conditions MPPC : 100pixels Pixel position : center

(X=5,Y=6) Laser hitting area : within the

1pixel Wavelength : 532nm Used filter : for laser intensity

down to10-8

We think laser intensity 160 corresponds to 1photon injection, because this value is beginning of max of 1photon and min of 0photon

Efficiency of 0pe, 1pe vs. Laser intensity● : Efficiency of 0photon event▲ : Efficiency of more than 1photon event

Laser intensity 160for 1photon injection

6. Readout from scintillator using WLS fiber

We connected scintillator and MPPC through wavelength sifter fiber and tried beta ray test

Measurement conditions Scintillator : 10x40x2mm strip type Source : 90Sr (beta-ray) WLS fiber : Φ1.0mm, length 20cm, Y-11 (Kuraray) Trigger : scintillator + PMT MPPC : first MPPC (100pixels)

Setup