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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. - PowerPoint PPT Presentation
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Muon Barrel Geometry Studies
Luca ScodellaroMuon Barrel Workshop
July 6th, 2010
OutlineStudies of the latest hardware-based
barrel geometryStudies for a standalone barrel
geometry with tracksInclusion of quality control
measurements
Studies of Latest HW GeometryLatest 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 asymmetryLook for systematic effects
Bottom-Top AsymmetryComparison of residual distributions
Top
Bottom
Old collectionNew collection
Performance of HW GeometryMeans of ∆X distributions
Performance of HW GeometryMeans of ∆dX/dY distributions
Performance of HW GeometryMeans of ∆Y distributions
Performance of HW GeometryMeans of ∆dY/dZ distributions
Bottom-Top Comparison
(mrad)
(mrad)
Mean distributions for hemisphere Bottom sectorsTop sectors
Comparison by Station
(mrad)
(mrad)
Mean distributions for station Station 1 to 2Station 2 to 3Station 3 to 4
Wheel to Wheel Twist Select tracks crossing two wheelsUse DT segments connecting neighbour chambers: (final station-initial station)=±1 (final wheel-initial wheel)=±1Assumeing YB0 as a reference and
extrapolating DT segments towards external wheels:
no significant twist of wheels observed
Wheel to Wheel TwistGlobal results
W-2 vs W-1 W-1 vs W0
W1 vs W0 W2 vs W1
Wheel to Wheel TwistStation by station results
Station 1 to station 2
Station 2 to station 3
Station 3 to station 4
Standalone Geometry with TracksHardware alignment close to its design
precisionAlignment with respect to the tracker might
suffer for several effects > track misalignment, B field, material
descriptionWe want to improve our standalone
description of the barrel using tracksMillepede approach based on a linear
approximation of residuals: R = B∆p + AδB matrix hard to describe in a non-uniform
magnetic field
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)
Standalone Geometry with Tracks
Residual DistributionsYB0, Sector 11, Station 2
(mrad)
Corrected distributionUncorrected distribution
Mean Distributions
(mrad)
(mrad)
Corrected geometryUncorrected geometry
Quality Control MeasurementCorrection distribution
Segment Validation
(mrad)
(mrad)
ConclusionsWe 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