The 2011 Tracker misalignment scenario
description
Transcript of The 2011 Tracker misalignment scenario
R. Castello (UC Louvain)
on behalf of the Tracker alignment group
The 2011 Tracker misalignment scenario
CMS AlCa meetingCern, 22/11/2011
Motivations for a new scenario
Previous scenario (TrackerAlignment_2010Realistic) provided a worse description of the real remaining misalignment and global deformations on data
Aim: a new one which performs closer to the current data alignment in view of 2012
Mostly in: DMR/residual distribution in the Endcap momentum biases in resonances decays (mass VS muon phi)
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Input dataset and studies performed
Current alignment on data performed mainly with MinBias+Cosmics A balanced input of ALCARECO (MC):
Isolated muons from W (16.3 M tracks) Isolated muons from QCD-mu enriched events (2.3 M tracks) Minbias tracks (450k events ~ 4.5 M tracks) Zmumu events using mass constraint (390k events) Peak mode cosmics (1.8 M used tracks) Deco mode cosmics (1.7 M used tracks)
Opportunely re-weighted to match the pT//phi track distribution on data
Several strategies studied: Starting from Startup MC + bow parameters from data Starting from ideal MC + small random noise + no bow mis-alignment Starting from ideal MC + bow parameters from data different weigh to the cosmic sample
Lesson learned: Including bow misalignment hit CPU limit: asked for an increasing The remaining Z mass bias versus muon phi seems to be completely
dominated by starting geometry (startup has a too large one w.r.t. data): intermediate starting point
Weighting cosmics (x2, x0.5) has almost no impac: discareded for now
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Final strategy
Final solution was to create an “intermediate” starting geometry Module by module differences between Ideal and Startup scenario
extracted (ID-ST) Differences applied on top of Ideal MC sceanrio and used as starting
point for alignment procedure with the input dataset described Three sizes:
Ideal02= ID-ST x 0.2
Ideal03= ID-ST x 0.33
Ideal05= ID-ST x 0.5
Bowed sensors param from data included as misalignment
on top of the starting geometry
Same alignment strategy usedfor data (one iteration)
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ID vs Startup ID vs Ideal03
Validation
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Bowing deformations
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DMR (Barrel)
Previous scenario already performing good in the Barrel: small changes
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Ideal MCdata geometryStartup MC scenarioNew MC scenario
DMR (Endcaps)
New MC scenario better matches the data in the Endcap Last improvements in the data alignment are better described by
this scenario
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Ideal MCdata geometryStartup MC scenarioNew MC scenario
Mass Vs muon phi
Remaining amplitude (05Delta) closer to data now, w.r.t. previous MC Startup scenario
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Mass Vs muon phi (Barrel/Endcap)
Different behavior between Barrel EndCap Closer performance to data in the Endcap, Barrel still a bit optimistic.. Starting geometry “subdetector dependent” has been produced for
accounting this, but no time to validate and sign-off
Potential candidate: MC_idealplus05Delta
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TEC -Barrel
Z mass peak
Good matching in the Z mass shape and resolution
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McS
cean
rio_Ide
al05
IDEAL vs Mcsceanrio_ID05 Data vs Mcsceanrio_ID05
Caveat: not normalized
Validation in other variables: mass vs (_mu1; _mu2)
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Overall shift, but trend more similar to data
Cosmic track splitting
Not noticeable differences visible new scenario (BPIX cent) remarkably similar to IDEAL
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Ideal MCStartup MC scenarioNew MC scenario (BPIX centered)
Summary
A new MC misalignment scenario has been produced for the new MC production: Overall the behavior of the new scenario is quite good in describing the
data Close to the ideal geometry! It includes bowing deformation fitted in dataReady to be used: already uploaded in the db (PXB centered), seehttps://hypernews.cern.ch/HyperNews/CMS/get/calibrations/983.html
Still room for improvement: Study on-going for a MC scenario that better matches the data
performances in the Barrel region BUT AlCa+Offline groups had the urgency to move on with the MC
production asap to meet the deadlines imposed by the Physics groups.Payloads:TrackerAlignment_2011Realistic_v1_mcTrackerSurfaceDeformations_2011Realistic_v1_mc
Credits for this work : A.Agocs, J.Behr, A.Bonato, R.C., G.Flucke, N.Heracleous, K. Krajczár, G.
Vesztergombi R.Castello 14
BACKUP slides
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