DataGrid meeting, CSC V. Karimäki (HIP) Otaniemi, 28 August, 2000
March 3, 2009 V.Karimäki, Sensor planarity 1 1 Sensor planarity study (pogress report) V. Karimäki...
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Transcript of March 3, 2009 V.Karimäki, Sensor planarity 1 1 Sensor planarity study (pogress report) V. Karimäki...
March 3, 2009 V.Karimäki, Sensor planarity 11
Sensor planarity study(pogress report)
V. Karimäki
Project meeting
Helsinki 03.03.2009
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)
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
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
March 3, 2009 V.Karimäki, Sensor planarity 51
Verification with Monte Carlo
Parameterized surface Fitted surface
March 3, 2009 V.Karimäki, Sensor planarity 61
Model independent surface shape
By plotting weighted uncorrected mean residuals
Here MC
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
March 3, 2009 V.Karimäki, Sensor planarity 81
Residuals profile, uncorrected
v [cm]
March 3, 2009 V.Karimäki, Sensor planarity 91
Residuals profile, corrected
v [cm]
March 3, 2009 V.Karimäki, Sensor planarity 10
1
Residuals, uncorrected, a TOB mod
March 3, 2009 V.Karimäki, Sensor planarity 11
1
Residual correction for non-planarity
March 3, 2009 V.Karimäki, Sensor planarity 12
1
Corrected residual
March 3, 2009 V.Karimäki, Sensor planarity 13
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Sensor shape, example
March 3, 2009 V.Karimäki, Sensor planarity 14
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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