Sensor planarity study (pogress report) V. Karimäki
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Transcript of Sensor planarity study (pogress report) V. Karimäki
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March 3, 2009 V.Karimäki, Sensor planarity 11
Sensor planarity study(pogress report)
V. Karimäki
Project meeting
Helsinki 03.03.2009
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March 3, 2009 V.Karimäki, Sensor planarity 21
Recall the basic idea
Q: track impact point at planar sensorP: true impact point at curved sensor near the true hit positionQ': point where our flat detector model assumes the hit lies
Departure from planarity causes a systematic offset:
u = (du/dw)*wP
du/dw=t1/t3 from track direction t = (t1,t2,t3)
Our CMSSW detector model: planar sensors (w=0)
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March 3, 2009 V.Karimäki, Sensor planarity 31
Hit correction for non-planarity
Corrected u-coordinate: uc = uh - u = uh - (t1/t3)*w [1]
So preserve the detector model, but
do correction
From [1]:
w=(t3/t1)* u
For fixed position (u,v):
w=<(t3/t1)*u> [2]
So systematics (u) in residuals give an estimate of w
i.e. the surface coordinates, computing [2] in bins
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March 3, 2009 V.Karimäki, Sensor planarity 41
Sensor curvature can be studied
1. Parametrizing shape: w=au2+buv+cv2 and fitting a,b,c
2. Model independent sensor shape by plotting mean residuals weighted with
(t3/t1) as a function of u,v
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March 3, 2009 V.Karimäki, Sensor planarity 51
Verification with Monte Carlo
Parameterized surface Fitted surface
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March 3, 2009 V.Karimäki, Sensor planarity 61
Model independent surface shape
By plotting weighted uncorrected mean residuals
Here MC
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March 3, 2009 V.Karimäki, Sensor planarity 71
Sensor shape study in cosmics
CRAFT data CMSSW TOB and TIB so far Begin with non-aligned data Pick up a few sample modules
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March 3, 2009 V.Karimäki, Sensor planarity 81
Residuals profile, uncorrected
v [cm]
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March 3, 2009 V.Karimäki, Sensor planarity 91
Residuals profile, corrected
v [cm]
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March 3, 2009 V.Karimäki, Sensor planarity 10
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Residuals, uncorrected, a TOB mod
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March 3, 2009 V.Karimäki, Sensor planarity 11
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Residual correction for non-planarity
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March 3, 2009 V.Karimäki, Sensor planarity 12
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Corrected residual
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Sensor shape, example
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Summary
By simple Monte Carlo:Demonstrated method to fit sensor shapeMethod to correct hit positionsDemonstrated model independent way to
look for possible sensor curvatureCosmics: First studies using TOBNo significant effects so far Further studies with many more modules