response property between fiber and mppc on ecal prototype
DESCRIPTION
Response property between fiber and MPPC on ECAL Prototype. 2011 年 03 月 03 日 High Energy Physic Laboratory Choi Weon Seok. Purpose : Problem of ECAL Prototype. MPPC. Effective pixels contacted with WLS. Scintillator. MPPC. 1mm. 1mm. WLS-fiber. - PowerPoint PPT PresentationTRANSCRIPT
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Response property between fiber and MPPC on ECAL Prototype
2011 年 03 月 03 日High Energy Physic Laboratory Choi Weon Seok
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Purpose : Problem of ECAL Prototype
Hole for WLS-fiber
MPPC
WLS-fiber
Scintillator
Effective pixels contacted with WLS
Location of hole is not fixed
This effect might cause change of effective pixel number for every MPPC on ECAL prototype.
1mm
1mmSurface of MPPC
MPPC
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Purpose: Response Curve of MPPC
Maximum photon number which MPPC can detect in an event, is limited by pixel number of MPPC itself.
⇒ MPPC response looses linearity to incident photon number
Response Curve would be affected by MPPC/fiber mismatch
It is needed to search saturation curve for every MPPC on ECAL prototype.
Detected Photon number of MPPC
Real Photon number(PMT response)
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Scintillator
lensePolarlizing plate x2
glass
MPPC
WLS- fiber
Pico-secLASER
PMT
λ: 408nm
Experiment: Setting
Pico-second LASER is used as light source.
Intensity is adjusted by two polarizing plate.
PMT is applied to estimate real photon number.
Light source for PMT is the LASER reflected by glass .
PMT
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Experiment : Response Curve (effect of MPPC/fiber mismatch )
The effective number of pixels decreases as MPPC/fiber mismatch increases
Photon number of MPPC detected
PMT response
MPPCscintillator
WLS-fiber
Before
After
before
after
Lifting up
132547:92873: afterNbeforeN pixpix
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Experiment : Response Curve (effect of MPPC/fiber mismatch )
Fitting function above doesn’t fit well the data in the whole x range. use the function above in low x range, and evaluate ⇒ pixN
))/exp(1( pixpix NxNy
Photon detected by MPPC
:pixN Effective pixel number of MPPC
: Photon Detection efficiency
:x Real photon number (PMT response)
Fitting Function
:y
]))0/[]1[exp(1](0[ x
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Experiment : Response Curve ( 36 MPPCs on ECAL prototype )
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Possible reasons for data dispersion are,
• accuracy of estimated by fitting
• change of the state of MPPC/fiber mismatch
Experiment : Correlation of Npix &MIP const
pixN
58.0r
Yaxis: MIP calibration constant (at 2008/2009 Fermi Lab)
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Conclusions I’ve measured MPPC response curve with pico-second LASER.
It seems like time structure of incident light affects a lot.⇒
The effect of MPPC/fiber mismatch on response curve has been measured. It is needed to find response curve for each MPPC on ECAL prototype.⇒
By evaluating with fitting function and comparing it with MIP const, it seems like there is correlation between them.
Tasks Research to understand response curve more deeply.
Confirming the state of MPPC/fiber mismatch by measuring cosmic muon and compare with FNAL data.
Conclusions&Tasks
pixN
10元の slide に戻る( Click )
The Way of Estimation
When you differentiate ideal fitting function 、 you will get
Thus, I determined the fitting range by searching linear data range when plotting difference quotient data.
pixN
x
dx
dy exp
xN
ey
pix
logloglog
: linear equation
11元の slide に戻る( Click )
The Way of Estimation
理想の fitting 関数を微分してみると、
もし、測定結果の分布の差分を取って直線的な傾向があるように見えるところがあれば、そこでは時間構造の影響が少ないと思われる。 ⇒この範囲で fitting.
pixN
x
dx
dy exp
xN
ey
pix
logloglog
: x に対する 1 次関数
12元の slide に戻る( Click )
The Way of Estimation]))0/[]1[exp(1](0[ x
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It is obvious that the gradient changes gradually. (slide 11)
There are two parameters which can affect gradient, εand Npix. ( slide10 )
Assuming εdepends on x like ,
and replace this function with
元の slide に戻る( Click )
Reforming Fitting Function
lxaex
0)(
14元の slide に戻る( Click )
Correlation of new Npix/MIP const (72 MPPCs)
r: 0.55
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BACK-UP
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Experiment: Setting
元の slide に戻る( Click )
LASER
Scintillator
PMT
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Purpose: Response Curve
Geiger mode で動作させる MPPC の各 pixel は、同時に光子が入射しても一定の信号を出す。 ⇒入射光子数が多くなくと、応答の線形性が落ちる
linear
真の光子数
))/exp(1( pixpix NxNy
:y MPPC の検出光子数
:pixN MPPC の有効 pixel 数 :光子検出効率
元の slide に戻る( Click )
MPPC の検出光子数
実際には PMT の応答を用いる
:x 入射光子数
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Experiment : Response Curve
元の slide に戻る (Click)
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Simulation results: when incidence light has time structure
入射光が時間的構造を持っているとき、理想的な saturation は起こらない .
このときは理想的な saturation の式では fitting できない .
By Mr. Sudou (Tsukuba Univ.-2008)
元の slide に戻る
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Scintillator を通したときの応答曲線
高い領域でよりは Fitting できているように見えるが、( x 軸)低領域では時間構造 の影響が少ないからだと思われる .
By Hiroko Koike(tsukuba-2010)
1600pixel
400pixel
元の slide に戻る
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MPPC に直接入れて見たとき
MPPC に直接 LASER を入れたときの分布。 Scintillator のときに比べては小さいが、徐々に上がる成分は少し見える。 ⇒ LASER そのものの時間構造によるものと思われる。
元の slide に戻る
23元の slide に戻る( Click )
Response Curve with non fiber scintillator(kuraray)
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PMT の印加電圧設定
真の光子数に対応させる PMT の応答が入射光子数に対して線形性を失うと扱えない .
LASER の強度を最大にしたときの印加電圧による PMT の増倍率の様子を調べて印加電圧を設定
bVA
bVA logloglog
元の slide に戻る( Click )
PMT の増倍率
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反射光& WLS を用いるときの PMT の応答 これまでは、応答曲
線を調べるときには、scintillator の光を fiberで集め、両端をそれぞれ MPPC,PMT に入れて測定
しかし本実験ではそれができないため、反射波を用いる。 ⇒反射波と fiberに対しての PMT の反応が線形性を持つかを見る必要がある
元の slide に戻る( Click )
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LASER
The LASER used is Picosecond Injection LASER(PiLAS) of Advan-ced Laser Diode Systems
It is possible to adjust intensity by changing “Tune” parameter. Every data are measured under Tune 50%.
元の slide に戻る( Click )
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d
MPPC の検出光子数の計算
newphoton dDN /
1 光子に対する積分電荷量( d )を測定
High gain mode Low gain mode (amp なし )
D
光源に対する応答の積分電荷量( D )を測定
amp の増倍率を補正して、 amp なしの時の 1 光子に対する積分電荷量( )を計算
newd
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Contents Backgrounds
Purpose Problems Response Curve of MPPC
Experiment Setting Response Curve
Conclusion&Tasks