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Muon Barrel Geometry Studies

Muon Barrel Geometry Studies. Luca Scodellaro Muon Barrel Workshop July 6 th , 2010. Outline. Studies of the latest hardware-based barrel geometry Studies for a standalone barrel geometry with tracks Inclusion of quality control measurements. Studies of Latest HW Geometry.

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Muon Barrel Geometry Studies

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  1. Muon Barrel Geometry Studies Luca Scodellaro Muon Barrel Workshop July 6th, 2010

  2. Outline • Studies of the latest hardware-based barrel geometry • Studies for a standalone barrel geometry with tracks • Inclusion of quality control measurements

  3. Studies of Latest HW Geometry • Latest barrel geometry sign-off at the PVT meeting on May 12th and used for ICHEP • Use DT segments to study relative alignment of neighbour chambers in the same sector • Use new track collection with t0 correction from May 24th reprocessing > bottom-top asymmetry • Look for systematic effects

  4. Bottom-Top Asymmetry • Comparison of residual distributions Top Old collection New collection Bottom

  5. Performance of HW Geometry • Means of ∆X distributions

  6. Performance of HW Geometry • Means of ∆dX/dYdistributions

  7. Performance of HW Geometry • Means of ∆Y distributions

  8. Performance of HW Geometry • Means of ∆dY/dZdistributions

  9. Bottom-Top Comparison (mrad) (mrad) • Mean distributions for hemisphere Bottom sectors Top sectors

  10. Comparison by Station (mrad) (mrad) • Mean distributions for station Station 1 to 2 Station 2 to 3 Station 3 to 4

  11. Wheel to Wheel Twist • Select tracks crossing two wheels • Use DT segments connecting neighbourchambers: (final station-initial station)=±1 (final wheel-initial wheel)=±1 • Assumeing YB0 as a referenceand extrapolating DT segments towards external wheels: no significant twist of wheels observed

  12. Wheel to Wheel Twist • Global results W-2 vs W-1 W-1 vs W0 W1 vs W0 W2 vs W1

  13. Wheel to Wheel Twist • Station by station results Station 1 to station 2 Station 2 to station 3 Station 3 to station 4

  14. Standalone Geometry with Tracks • Hardware alignment close to its design precision • Alignment with respect to the tracker might suffer for several effects > track misalignment, B field, material description • We want to improve our standalone description of the barrel using tracks • Millepede approach based on a linear approximation of residuals: R = B∆p + Aδ • B matrix hard to describe in a non-uniform magnetic field

  15. Standalone Geometry with Tracks • Trying an approach based on DT segment > for small movements, we can assume ∆p to depend only on chamber movements B ∆p = ACδinit = Aδfinal > simplified χ2 minimization • Using half statistic to fit chamber movements inside a sector, the other half to test the new geometry with the usual method (tighter cuts)

  16. Residual Distributions (mrad) • YB0, Sector 11, Station 2 Corrected distribution Uncorrected distribution

  17. Mean Distributions (mrad) (mrad) Corrected geometry Uncorrected geometry

  18. Quality Control Measurement • Correction distribution

  19. Segment Validation (mrad) (mrad)

  20. Conclusions • We studies the performances of the latest hardware-based barrel geometry > still some top-bottom asymmetry observed > no major systematic so far identified with segments • Quality control measurement added to internal chamber description • Starting to develop a standalone track-based geometry

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