New test result of MPPC

M.Taguchi(kyoto)

Contents

• New MPPC sample

• Noise rate,gain,crosstalk rate

• PDE

• Long term stability

New MPPC sample recently we got

• HPK32(400pixel) ×3

Operating voltage : 68~69V

1p.e signal width:~20ns

• HPK53(100pixel) ×3

Operating voltage:68~69V

1p.e signal width:~50ns

•HPK say these have higher PDE than old samples

•The test result of HPK14(100pixel) that we used at beamtest will be presented for comparison

Noise rate measurement

15℃

20℃

25℃

■ 0.5p.e threshold ▲ 1.5p.e threshold

1MHz

100kHz

68.4 68.4 69.6 69.4

15℃

20℃

25℃

Bias voltage Bias voltage

　　 HPK32(400pixel) HPK53(100pixel)

Gain measurement@T=20℃

HPK53(100pixel)

HPK32(100pixel)

1×106

3×106

1MHz500kHz

gain

0.5p.e threshold noise rate

HPK14(100pixel)

•Gain of new samples >105,so satisfy T2K requirement

Crosstalk rate measurement@T=20℃

0.5p.e threshold noise rate

1MHz500kHz

0.2

Crosstalk rate HPK53(100pixel)

HPK14(100pixel)

HPK32(100pixel)

0.1

•Crosstalk rate of new samples is still high

(T2K requires crosstalk rate<0.1)

PDE measurement@T=15℃

MPPC

½inch PMT

scan1mmφslit

MPPC

½inchPMT

scan

1mmφfiber

Blue LED

Blue LED

1mmφfiber

•With this set up all the light going through 1mmφslit inject to the active area of MPPC

•With this set up some light from a fiber don`t reach to the active area of MPPC because there is a distance(~0.8mm) between surface cover and active area

•Ratio of MPPC p.e to PMT p.e measured by this set up is defined as PDE

•Ratio of MPPC p.e to PMT p.e measured by this set up is defined as effective PDE

PDE measurement@T=15° ▲ 　 PDE

Noise rate(kHz)

ノイズレート(kHz)

ノイズレート (kHz)

•PDE is showed with relative value to PMT

900

500

2

HPK53(100pixel) HPK32(400pixel) HPK14(100pixel)

900500 900550 400 900Noise rate(kHz) Noise rate(kHz)

2

1

■ effective PDE

•PDE of new sample is 2 times larger than that of old one•Effective PDE is 50~60% of PDE We requested the improvement of MPPC packaging to HPK

Raw signal of new sample

HPK53(100pixel) Noiserate=1345kHz

HPK32(400pixel) Noiserate=1246kHz

•Noise with large pulse height ( ～ 10p.e) is observed when noise rate becomes >1MHz

•There is no problem because T2K requires noise rate <1MHz

Long term stability test@T=20℃

4 layers

½ inch 　 PMT

HPK32(400pixel)

Cosmic ray

Bias voltage 68.8V

gain 5.6×105

0.5p.e th noiserate 800kHz

Crosstalk rate 0.1

Effective PDE(including crosstalk)

1.2

Trigger counter

•Cosmic trigger

•LED trigger(for monitaring MPPC gain)

•Pedestal trigger(for monitaring noise rate)

Blue LED

•Test the stability of gain,noise rate,p.e for MIP

MPPC parameter

3 different triggers

Cosmic ray event

MPPC PMT

20 20p.e p.e

60 60

14.8p.e 16.2p.e

gain

5%

5%

RMS/mean=2.5%

5%

5%

40hour 40 hour

Noise rate

5.7×105

839kHz

Stability of MPPC gain and noiserate

RMS/mean=4.3%

Peak adc count for MIP

5%

5%

Peak adc count/gain for MIP

5%

5%

Stability of MPPC Light yield for MIP

RMS/mean=4.0% RMS/mean=2.9%

14.7p.e

40 hour 40 hour

Correction by gain

summary

• New MPPC samples have about 2 times larger PDE than that of old ones

• MPPC light yield for MIP~15p.e (at the point where noise rate and gain satisfy T2K requirement)

• Gain stability ~3% ,noise rate stability~4%

• Stability of light yield for MIP~3%

(about 2 days)

Back up

LED event

MPPC PMT

Staibility of PMT gain

5%

5%

40hour

RMS/mean = 4.7%

1p.e adc count

5%

5%

40hour

Peak adc count for MIP Peak adc count/gain for MIP

5%

5%

16.5p.e

Stability of PMT light yield for MIP

40hour

RMS/mean=4.6% RMS/mean=3.1%Correction by gain

Operating voltage range which satisfy T2K requirement

•HPK32(400pixel)

68.2 ～ 68.8V

Upper limit ： 1.5p.e th noise rate<50kHz

Lower limit ： PDE >15%

•HPK53(100pixel)

68.3 ～ 69.1V

Upper limit ： 1.5p.eth noise rate<50kHz

Lower limit ： PDE>15%

Recovery time

HPK32 (400pixel)

LED1

LED2

•Fire all pixels with LED1 and study the response of LED2 with the delay to LED1

LED1 LED2

120ns

•Saturation signal was observed by LED2 even with the 120ns(signal width) delay

400p.e

recovery time is about the same as signal width

LED1 LED2

160ns

400p.e