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 ■ 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

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

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

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

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

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℃ 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)

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

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

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

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 1p.e adc count 5% 5% 40hour RMS/mean = 4.7%

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

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%

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