The Millennium Project Priorities (ranked by MPPC members) For MPPC meeting discussion July 2009.
MPPC update
description
Transcript of MPPC update
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MPPC update
S.Gomi, T.Nakaya,M.Yokoyama, M.Taguchi, (Kyoto University)
T.Nakadaira (KEK)
Nov.8.2006 KEK
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Contents
Ceramic package of MPPC
• We obtain the latest sample of MPPC this October. – Ceramic package, prepared for T2K experiment.– 100pixel×10, 400pixel×10
• We measured the fundamental performance of this sample.– Gain– Noise rate– Cross-talk rate– Photon detection efficiency ( PDE )
5mm6
mm
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Gain
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
Gain 400pixel
610
5105
Bias voltage [V]69.6 70 70.6
Gain 100pixel
6103
610
Bias voltage [V]69 69.5 69.8
• Gain of old sample was…– 1.0×106~3.0×106 (100pixel)– 0.4×106~1.0×106 (400pixel)
Gain of new sample is not so Gain of new sample is not so changed compared to old sample.changed compared to old sample.
Estimated by 1p.e signal peak .
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The measurement of noise rate• The noise rate is measured by counting the rate
of signal with their height over the threshold, imposed on 0.5p.e and 1.5p.e .
( The old sample have ~1.2MHz 1p.e noise rate. )
Noise signal of 100pixel MPPC at 25 degree.
( integrated )
1 p.e
0.5 p.e = threshold
1.5 p.e = threshold
“ 1p.e noise ”
“ 2p.e noise ”
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Noise rate
• 1p.e noise rate is about ~0.4 MHz. (old ~1.2 MHz)• 2p.e noise rate is about ~0.2 MHz. (old ~0.2 MHz)
100kHz
400kHz
Bias voltage [V]69.2 70 70.4
Noise rate [ kHz ] 400pixelNoise rate [ MHz ] 100pixel
100kHz
500kHz
Bias voltage [V]
69.1 69.5 70
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
1p.e noise
2p.e noise
1p.e
2p.e
Improved!Improved!
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The measurement of cross-talk rate
• Sensitive area of 100pixel type is enlarged by 40%. Geometrical efficiency is increased.
• The separation between pixels is smaller than the old sample. Cross-talk rate may be increasedCross-talk rate may be increased
Old sample( 100pixel )
New sample( 100pixel )
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• The probability of cross-talk is estimated by the number of 1p.e .
Measurement of cross-talk rate
ondistributi-Poisson
-measuredondistributi-Poisson
)1(P
P(1)- )1(P rate talk cross
The cross talk rate is determined.
The number of pedestal are free to cross-talk
• the number of each p.e is assumed to be follow the Poisson distribution
The number of 1p.e : P(1)( estimated by pedestal )
||without cross-talk
The number of 1p.e : P(1)( measured )
||with cross-talk
This difference corresponds to the decrease by cross-talk.
measurement
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Cross-talk rate
( Cross-talk rate of the old sample is ~30%. ) Cross-talk rate of new sample is ~1.6 times Cross-talk rate of new sample is ~1.6 times larger than old sample.larger than old sample.
10%
50%
Cross-talk rate 400pixelCross-talk rate 100pixel
10%
50%
Bias voltage [V]69.6 70 70.6
Bias voltage [V]69 69.5 69.8
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
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relative PDE measurement
MPPC
1mmφslit
Blue LED
( total area 1mm2)
PMT
p.e.(PMT)
p.e.(MPPC)PDE relative
PMT made by HPK, type H8643
set up Moving stage
• Geometrical efficiency is larger than that of the old sample. So, PDE of new sample should be higher.
• PDE relative to PMT is measured.
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relative PDE
• PDE is about 2~3 times higher than that of PMT.
(Old sample was ~2×PMT) ~1.4 times larger PDE than old ~1.4 times larger PDE than old sample. sample.
1
2
Relative PDE 400pixelRelative PDE 100pixel
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2
3
Bias voltage [V]69.6 70 70.6
Bias voltage [V]69 69.5 69.8
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
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Summary of measurement
Old sample New sample
Gain
Noise rate(1p.e) [ kHz ] ~1200 ~400Cross-talk rate ~30% ~50%PDE
66 103~101
PMT 2~
66 103~101
• The new sample have good performance! But, Cross-talk become worse. feed back to Hamamatsu
PMT 3or 2~
Improved!Improved!
Improved!Improved!
Become worse…Become worse…
About the region the gains of 2sample are same…
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Future plan…• We will check the device-to-device variation for 500
MPPCs in this ceramic package next March. • So, we have to make system to test many samples. • We want to measure as many sample as possible at
once.– Plastic connector– Read out electronics
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Supplements
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Gain bdBIAS V V V
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
610
6105
Gain 400pixelGain 100pixel
6103
610
0.2 1 1.6 0.8 1 2 2.4
V V
15
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
Noise rate
• This new sample have noise rate less than the half of old sample.
100kHz
400kHz
Noise rate [ kHz ] 400pixelNoise rate [ MHz ] 100pixel
100kHz
500kHz
0.4 1 1.6 0.5 1 1.5 2 2.3
1p.e
2p.e
V V
bdBIAS V V V
1p.e
2p.e
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Cross-talk rate
• Cross-talk rate is a function of V.
10%
50%
1 2Delta V
Cross-talk rate 400pixelCross-talk rate 100pixel
10%
50%
0.2 1 1.6 0.8 1 2 2.4
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
V V
bdBIAS V V V
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relative PDE
• PDE is a function of Delta V.
1
2
Relative PDE 400pixelRelative PDE 100pixel
1
2
3
0.2 1 1.6 0.8 1 2 2.4
BlueBlue : : 15degree15degreeGreenGreen : : 20degree20degreeRedRed : : 25degree25degree
V V
bdBIAS V V V
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Set up for measuring linearity
set up
MPPCThe number of photons emitted to MPPC are monitored by PMT.
PM
T
Paper ( to shade off LED light )
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00fired N
exp1NNx
Linearity
• The green line shows the expectation value calculated from number of pixels.
ronphotoelect injected :
pixels ofnumber the:N0
x
BlueBlue : DATA plot: DATA plotGreenGreen : expectation: expectation
Linearity 400pixel
Injected photoelectron per pixel F
ired
pix
el [
% ]
MPPC can operate as linear device.MPPC can operate as linear device.~25p.e about 100pixel type~100p.e about 400pixel type.
linear
Linearity 100pixel
Fir
ed p
ixel
[ %
]
Injected photoelectron per pixel
linear
25%25%
BlueBlue : DATA plot: DATA plotGreenGreen : expectation: expectation