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Sensor planarity study (pogress report) V. Karimäki

Project meeting Helsinki 03.03.2009. Sensor planarity study (pogress report) V. Karimäki. Recall the basic idea. Our CMSSW detector model: planar sensors (w=0). Q: track impact point at planar sensor P: true impact point at curved sensor near the true hit position

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Sensor planarity study (pogress report) V. Karimäki

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  1. Project meeting Helsinki 03.03.2009 Sensor planarity study(pogress report) V. Karimäki

  2. Recall the basic idea OurCMSSW detector model: planar sensors (w=0) Q: track impact point at planar sensor P: true impact point at curved sensor near the true hit position Q': point where our flat detector model assumes the hit lies Departure from planarity causes a systematic offset: Du = (du/dw)*wP du/dw=t1/t3 from track direction t = (t1,t2,t3)

  3. Hit correction for non-planarity • Corrected u-coordinate: uc = uh - Du = uh - (t1/t3)*w[1] • So preserve the detector model, but do correction • From [1]: w=(t3/t1)* Du • For fixed position (u,v): w=<(t3/t1)*Du> [2] • So systematics (Du) in residuals give an estimate of w i.e. the surface coordinates, computing [2] in bins

  4. Sensor curvature can be studied • Parametrizing shape: w=au2+buv+cv2 and fitting a,b,c • Model independent sensor shape by plotting mean residuals weighted with (t3/t1) as a function of u,v

  5. Verification with Monte Carlo Parameterized surface Fitted surface

  6. Model independent surface shape • By plotting weighted uncorrected mean residuals Here MC

  7. Sensor shape study in cosmics • CRAFT data • CMSSW • TOB and TIB so far • Begin with non-aligned data • Pick up a few sample modules

  8. Residuals profile, uncorrected v [cm]

  9. Residuals profile, corrected v [cm]

  10. Residuals, uncorrected, a TOB mod

  11. Residual correction for non-planarity

  12. Corrected residual

  13. Sensor shape, example

  14. Summary By simple Monte Carlo: • Demonstrated method to fit sensor shape • Method to correct hit positions • Demonstrated model independent way to look for possible sensor curvature Cosmics: • First studies using TOB • No significant effects so far • Further studies with many more modules

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