Multi Pixel Photon Counter T. Nakadaira KEK
Introduction MPPC is new semiconductor photon sensor Technology is very similar to SiPM. Under development by Hamamatsu Photonics (HPK) MPPC have not been listed in their products yet. HPK delivered many kinds of test samples to T2K and ILC-CAL. R&D groups in JP-HEP. ILC Calorimeter (Kobe U, Niigata U, Sinsyu U, Tsukuba U) T2K Near detector (Kyoto U) KEK Detector Technology Development group 1mm
Principal of MPPC Micro APD pixel array # of pixels 100, 400, 1600 Each pixel is operated in Geiger-mode. Bias voltage = 40 ~ 70V Only one operation parameter Outputs from all pixels are directory connected ( Wired-OR ) # of read out = 1 channel / device Pulse height of output signal # of hit pixels # of hit pixels # of photons Gain = ~10 6 No amplifier is needed Compact size Suitable for optical fiber readout. Works in the Magnetic field. High QE is expected. Expected cost is ~ $10 / device. 1p.e 2p.e 3p.e Raw signal HPK 100pixel MPPC 1mV/div 100ns/div
R&D Items Measurement of basic performance w/ LED Gain, Noise rate, Cross talk, Photon Detection Efficiency (PDE), linearity These parameters strongly depends on the bias voltage. Pixel by Pixel uniformity Inject photon to pixel by pixel using well focused laser beam 532nm Laser system @ Niigata University 825nm Laser system @ KEK Beam test @ KEK 12GeV PS test beam line Detect the particle using Plastic-scintillator + WLS optical fiber + MPPC Beam data is taken in Nov, 2005 Analysis is in progress.
Photon counting by MPPC Charge distribution # event 500 000 LED light (HPK 100 pixel) We can distinguish up to 45 p.e. peak. Variation of Intervals between peaks is in 2%. Gains for each pixels are uniform. 2p.e 3p.e 1p.e 500 # event 400 500 000 0p.e 300 Increasing LED light 200 30p.e 500 100 0 80 100 120 140 160 180 200 220 240 0 250 300 350 400 450 500 550 600
MPPC Gain Gain = 8 10 5 ~ 2 10 7 Gain x 10 4 2000 10 7 1900 1800 1700 1600 1500 5 10 7 1400 HPK 100 pixel Gain x 10 3 6400 6200 6 10 6 6000 5800 5600 5400 5200 5 10 5000 6 4800 HPK 400 Pixel 1300 4600 46.8 47.2 47.4 47.6 47.8 48 48.2 47 48.4 47.75 48 48.25 48.5 48.75 49 49.25 49.5 Bias Voltage (V) 47.5 Bias voltage (V) 49.
Noise Rate Measure the signal rate w/o LED light. Charge distribution for Noise 400 pixel # event 10 3 0p.e 1p.e w/o LED w/o LED 10 2 2p.e 0.5p.e 10 1p.e. pulse noise 1 0 100 200 300 400 500 600 700 80 Charge
Noise Rate v.s. Bias voltage (20 C) noise rate (Hz) 10 6 10 5 10 4 10 3 10 2 100 pixel 400 pixel 0.5p.e threshold 1.5p.e threshold 47 47.5 48 48.5 49 49.5 Bias voltage (V) 1MHz Noise > 1p.e. is less than 10 %
Cross talk among the pixels Cross talk is measures in 2 methods. Noise rate (Noise > 1.5 p.e ) / (Noise > 0.5 p.e) Discrepancy of charge distribution from Poisson distribution. HPK14 10 4 10 3 10 10 10 2 10 10 4 h1 10 Entries 50000 Mean 198.3 RMS 4.671 ratio 0.35 0.3 0.25 0.2 0.15 HPK 400pixel V=48.6 Poisson dist. Data 1 0.1 160 180 200 220 240 260 280 300 adc count 0.05 0.5p.e 1.5p.e 0 0 1 2 3 4 5 6 7
X-talk v.s. bias V ( ) X- talk Rate 0.35 0.3 0.25 by poisson law by noise rate 0.2 0.15 HPK100a 0.1 0.05 HPK400b 0 47 47.5 48 48.5 49 49.5 bias voltage (V)
Linearity measurement If the light intensity became large, several photons injected in a pixel. Counted as single photon because of the Geigermode operation. Linearity measurement is important to determine the number of pixels. Linearity is also affected by cross talk. Linearity is measured by changing the bias voltage to check the x-talk effect. We use the PMT as a reference of light intensity. PMT MPPC Blue LED
MPPC ADC HPK14 linearity count ADC(MPPC) ADC(MPPC) 300 250 200 150 100 50 it with line HPK14 linearity 700 600 500 400 300 200 100 Linearity (HPK 100 pixel) 0 0 5 10 15 20 25 30 35 ADC(PMT) PMT ADC count X-talk rate =0.03 X-talk rate =0.2 Discrepancy(%) HPK14 linearity ratio ratio 1.05 1 0.95 0.9 0.85 0.8 0.75 0.7 HPK14 linearity 1 0.95 0.9 0.85 0.8 0.75 0.7 10% 20% 20% 10 20 30 40 50 60 70 injected photo electron number 10% 20% M.Taguchi (Kyoto U) 50 0% 0% 20%@50p.e # of photon 20%@40p.e 0 0 10 20 30 40 50 ADC(PMT) 0.65 10 20 30 40 50 60 70 80 injeceted photo electron number # of photon
PDE (photon detection efficiency) # of photo electron in signal/ # of injected photon Geometrical Eff. (30~50%) Depends on MPPC type PDE=ε pixel Q.E. ε Geiger Quantum Eff. (60~80%) Depends on wave length DE relative to PMT is measured. PMT(13mmφ) PMT LED / LED Probability for p.e. to invoke Geiger discharge (60~80%) Depends on bias voltage Dispersion is not taken into account in calc. Blue LED 1mmφslit MPPC(1mm 2 ) 1mmφ WLS fiber
Measured PDE MPPC(p.e)/PMT(p.e) PDE(MPPC)/PDE(PMT) HPK14 Blue/ PDEgreen 1 0.9 PDE(%) PDE(MPPC) Red assuming PDE(PMT=2%) 12 Max: 12% 11 (PMT Q.E ~ 2%) 0.8 0.7 green 10 9 0.6 0.5 0.4 blue 350 450 550 650 300 400 500 600 700 noise rate(khz) noise rate (khz) 8 7 6 5 300 400 500 600 700 800 noise rate(khz)
Performance test w/ Laser Test MPPC pixel by pixel (HPK 100 pixel) Check the uniformity of efficiency in single pixel Pixel by Pixel deviation of gain and efficiency 825nm 50ps Laser Light source MPPC Micro Scope 100 m Spot size ~ 10µm XY moving stage (1µm pitch control)
Flat area: 60x60 µm 2 Efficiency Uniformity: Single pixel HPK 100pixel 100µm Sensitive region 70x70 m 10µm pitch Laser spot 700 600 1p.e. Charge dist. in a point y x 500 400 300 200 0p.e. Efficiency= signal>0.5 p.e / Total event 100 m 100 m 100 0 80 100 120 140 160 180
Uniformity: Pixel by Pixel Set laser spot @ center of each pixel Very good uniformity elative Gain r.m.s./mean = 3.6% HPK 100 pixel Relative Efficiency r.m.s./mean = 2.5% y 1.06 1.04 1.02 1 0.98 0.96 0.94 0.92 1mm 10 9 8 7 6 5 4 3 2 0 1 2 3 4 1 0 5 6 7 8 9 1mm 10 x 1.04 1.02 1 0.98 0.96 y 10 9 8 7 6 5 4 3 2 0 1 2 3 4 1 0 1mm 5 6 7 8 9 1mm 10 x
Summary& Prospect MPPC is promising device for photon counting. Gain ~ 10 6-10 7 Noise rate: O(1MHz) for >0.5 p.e., O(10~100kHz) for >1.5 p.e. X-talk rate: < ~0.2 Photon Detection Efficiency: comparable to PMT linearity: Discrepancy within 20% up to 40% of # of pixels Efficiency in single pixel is uniform Pixel by Pixel deviation of gain and efficiency is very small HPK delivered new samples to T2K and ILC-CAL group. Sample test in progress.
T2K MPPC T2K p MIP 5p.e. 0.5 1.4GeV/c proton & pion 100 event/spill beam size 1x1cm 2 4ch MPPC MPPC (HPK or Russia) 4 layers setup 64ch MAPMT (as reference) 1mm 1.3x2.5x50 cm 3 (K2K Scibar
HPK MPPC alignment HPK MPPC Y 0.8mm Z : 0.8mm Z X,Y : X X Y (1mm ) MPPC MPPC X,Y 20%,Z 60 40
MIP (p.e.) #event Photon Detection Efficiency (PDE =MPPC (1mm 2 ) PMT PDE HPK 70%, 100% MIP 160 140 120 100 80 60 40 HPK 13.3p.e. #event 180 160 140 120 100 p.e. 80 60 40 17.1p.e. MPPC 20 0 0 5 10 15 20 25 30 35 40 45 50 20 0 0 10 20 30 40 50 60 70
MIP (p.e.) 39 7.2 #17 73 13.3 #16 56 10.2 #14 54 9.9 #13 PMT (%) (p.e.) Serial# HPK PDE PMT 70% (p.e.) PDE PMT 100% (p.e 94 17.1 #14 126 22.9 #13 PMT (%) (p.e.) Serial# PDE Z MIP MAPMT 18.2p.e. PDE HPK X,Y MPPC T2K
p/ Separation Mean MIP Mean,r.m.s. MPPC 13.3p.e. MAPMT 18.0p.e. r.m.s. 6.2p.e. 6.6p.e 1.2GeV 1.0GeV 0.9GeV p 0.8GeV 0.7GeV 0.6GeV 1.2GeV 1.0GeV 0.9GeV p 0.8GeV 0.7GeV 0.6Ge 0.5GeV MPPC (PDE70%) 0.5GeV MAPMT (PDE100%)