1. New test result of MPPC
M.Taguchi(kyoto)

2. Contents New MPPC sample Noise rate,gain,crosstalk rate PDE
Long term stability

3. 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

4. Noise rate measurement
■ 0.5p.e threshold
▲ 1.5p.e threshold
HPK53(100pixel)
　　 HPK32(400pixel)
1MHz
100kHz
15℃
15℃
20℃
20℃
25℃
25℃
68.4
69.6
68.4
69.4
Bias voltage
Bias voltage

5. Gain measurement@T=20℃ gain 3×106 HPK53(100pixel)
Gain of new samples >105,so satisfy T2K requirement
HPK14(100pixel)
1×106
HPK32(100pixel)
0.5p.e threshold noise rate
500kHz
1MHz

6. Crosstalk rate measurement@T=20℃
HPK14(100pixel)
HPK53(100pixel)
0.2
Crosstalk rate of new samples is still high
(T2K requires crosstalk rate<0.1)
0.1
HPK32(100pixel)
0.5p.e threshold noise rate
500kHz
1MHz

7. PDE measurement@T=15℃ Blue LED MPPC 1mmφfiber 1mmφslit Blue LED MPPC
With this set up all the light going through 1mmφslit inject to the active area of MPPC
MPPC
½inch PMT
1mmφfiber
Ratio of MPPC p.e to PMT p.e measured by this set up is defined as PDE
scan
1mmφslit
Blue LED
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
MPPC
½inchPMT
1mmφfiber
Ratio of MPPC p.e to PMT p.e measured by this set up is defined as effective PDE
scan

8. PDE measurement@T=15° PDE is showed with relative value to PMT
■ effective PDE
HPK53(100pixel)
HPK32(400pixel)
HPK14(100pixel) 2 2 1
500
900
ノイズレート(kHz)
ノイズレート(kHz)
500
900
550
900
400
900
Noise rate(kHz)
Noise rate(kHz)
Noise rate(kHz)
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

9. 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

10. Long term stability test@T=20℃
Test the stability of gain,noise rate,p.e for MIP
Cosmic ray
Trigger counter
4 layers
HPK32(400pixel)
Blue LED
½ inch　PMT
MPPC parameter
Bias voltage
68.8V
gain
5.6×105
0.5p.e th noiserate
800kHz
Crosstalk rate
0.1
Effective PDE(including crosstalk)
1.2
3 different triggers
Cosmic trigger
LED trigger(for monitaring MPPC gain)
Pedestal trigger(for monitaring noise rate)

11. Cosmic ray event
MPPC
PMT
14.8p.e
16.2p.e 20 20 60 60
p.e
p.e

12. Stability of MPPC gain and noiserate5% 5%
839kHz
5.7×105 5% 5% 40
hour 40
hour
RMS/mean=2.5%
RMS/mean=4.3%

13. Stability of MPPC Light yield for MIP
Peak adc count for MIP
Peak adc count/gain for MIP 5% 5%
14.7p.e 5% 5% 40
hour 40
hour
RMS/mean=4.0%
RMS/mean=2.9%
Correction by gain

14. 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)

15. Back up

16. LED event
MPPC
PMT

17. Staibility of PMT gain
1p.e adc count 5% 5%
40hour
RMS/mean = 4.7%

18. Stability of PMT light yield for MIP
Peak adc count for MIP
Peak adc count/gain for MIP 5% 5%
16.5p.e 5% 5%
40hour
40hour
RMS/mean=4.6%
RMS/mean=3.1%
Correction by gain

19. Operating voltage range which satisfy T2K requirement
HPK32(400pixel)
Upper limit：1.5p.e th noise rate<50kHz
68.2～68.8V
Lower limit ：PDE >15%
HPK53(100pixel)
Upper limit：1.5p.eth noise rate<50kHz
68.3～69.1V
Lower limit：PDE>15%

20. Recovery time LED1 400p.e LED1 LED2 HPK32 (400pixel) LED2 160ns
Fire all pixels with LED1 and study the response of LED2 with the delay to LED1
Saturation signal was observed by LED2 even with the 120ns(signal width) delay
400p.e
LED1
LED2
 recovery time is about the same as signal width
120ns