Track-based Muon Alignment StatusYuriy Pakhotin

On behalf of Muon Alignment Group

Muon Barrel WorkshopMay 5th, 2011

https://indico.cern.ch/conferenceDisplay.py?confId=137060

OutlineUpdates to Muon Alignment with “twist-free” TrackerFix a problem with missing hits in stations 3 and 4Switch from Global Muon Tracks to Tracker MuonsAlignment with full 2010 data almost done• Collisions• Cosmics• Beam Halo

Alignment with 2011 data in development

List of Detailed Reports since last Barrel Workshop

1. Muon Alignment Meeting, Fri Feb 25th, 2011• http://indico.cern.ch/conferenceDisplay.py?confId=128860

• “TB muon alignment with twist-free tracker” by Aysen Tatarinov

2. Muon Alignment Meeting, Fri Mar 11th, 2011• http://indico.cern.ch/conferenceDisplay.py?confId=130953

• “CSC disk update with untwisted tracker” by Vadim Khotilovich

• “Muon Reco Validation for new endcap alignment” by Luca Scodellaro

3. Muon DPG Meeting, Mon Mar 14th, 2011• http://indico.cern.ch/conferenceDisplay.py?confId=130897

• “Barrel muon alignment with twist-free tracker” by Aysen Tatarinov

• “CSC disk update with untwisted tracker” by Vadim Khotilovich

4. Update on muon alignment, Tue March 15th, 2011• http://indico.cern.ch/conferenceDisplay.py?confId=126162#6

• “Update on muon alignment” by Yuriy Pakhotin

Twist in the EOY Tracker Geometry• Twist effect in End-Of-Year (EOY) Tracker geometry

• E.g. visible in reconstructed Zmm mass bias vs η

• “Twist-free” Tracker geometry is signed-off on Feb 23rd, 2011 at the Joint PVT/PO Meeting• http://indico.cern.ch/conferenceDisplay.py?confId=128328

from G. Flucke (DESY)for the TK Alignment group

EOY geometry

Twist-free geometry

twist angle

Seeded by EOY Tracker geometry: “TWIST” Seeded by “twist-free” Tracker geometry: NO “TWIST”

Muon Alignment in DT Wheels with “twist-free” TrackerHardware vs. Track-based alignment comparison

Twist effect in Barrel is significantly reduced! Current geometry based on HW, no corrections are needed

from A. Tatarinov (Texas A&M)

• Use latest “twist-free” Tracker Alignment as input

• CSC Rings are aligned as rigid bodies

• Chambers within rings already aligned

• Updated GPRs for tracker and muon system

• Compare CSC Ring positions in two geometries

• New “minus” EOY

• Observations:

• Small shifts (≈ 0.3 mm) in X and Y

• Due to changes in GPR

• Large twist (φZ ≈ ±1 mrad) in opposite

directions in +- endcaps

• Effect of the tracker “untwisting”

• Important to keep CSC alignment in sync with

Tracker geometry

• CSC Alignment was signed off

≈2 mradtwist angle

Update to CSC Alignment with “twist-free” Tracker

X

Y

φZ

from V. Khotilovich (Texas A&M)

Missing Hits in Station 3 and 4 regular gaps in distributions of global phi of global muons'

track hits in stations 3 and 4 were observed• muons pT > 20 GeV• Sample: /Mu/Run2010B-SingleMu-Dec22Skim_v2/RECO

gaps

Missing Hits in Station 3 and 4 cont’dOnly global muons tracks have missed hits. STA muons were

fine.Standalone Global

Missing Hits in Station 3 and 4 cont’dThe problem was fixed recently• RecoMuon/GlobalTrackingTool/GlobalTrajectoryBuilderBase.cc• Ad-hoc sorters removed• New code is in CMSSW >4.2.X

No gaps

Alignment with Tracker MuonsGlobal muons’ tracks were previously used• Large uncertainties were assigned to hits in muons system to

exclude bias in alignmentNow we are switching to Tracker muons’ tracks• Substantial change in code -- done• Validation is in progress• median plots show residuals RMS slightly better for tracker muons

w/ GLB muons w/ TRK muons

Updated Track-based AlignmentAlignment with full 2010 data almost done• Samples:

Collisions Cosmics Beam Halo

• New re-reco of 2010 data is just became available• A few minor issues need to be resolved

Alignment with new 2011 data is in development• Samples

Collisions and Cosmics No beam halo

Plans to include realistic APEs from covariance matrix

ConclusionTwist free Tracker geometry resolved the long standing

“twist problem” in muon alignmentUpdated CSC alignment is in-sync with trackerMissing hits in DT stations 3 and 4 fixedTracker muons’ tracks are used in TB alignment New alignment with re-reco 2010 data is almost doneAlignment with new 2011 data is in development