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L2 Muon Trigger Status Report: L2 seeding study. B. de la Cruz , C. Diez (CIEMAT, Madrid) Muon HLT Meeting 17th April, 2009. L2 seeds reminder. Parameters from L1 muon candidates converted into seeds for L2 muon reco  pt estimated at interaction point

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L2 Muon Trigger Status Report: L2 seeding study

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L2 muon trigger status report l2 seeding study

L2 Muon Trigger Status Report:

L2 seeding study

B. de la Cruz , C. Diez

(CIEMAT, Madrid)

Muon HLT Meeting

17th April, 2009

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

L2 seeds reminder

  • Parameters from L1 muon candidates converted into seeds for L2 muon reco

     pt estimated at interaction point

     global position (, ) of hit at second station (MB2/ME2) firing L1

  • A TSOS (L2 trajectory seed) is defined at the second station with this previous info and some initial errors assigned.

  • Great care needed, as info is not given at the same reference system

  • At this point, L2 pattern recognition starts

     Track parameters from seed propagated

    to innermost reachable muon chamber

     Forward pattern reco: navigation outward

     Bacward pattern reco: navigation inward

MB4

MB3

MB2

MB1

, 

pt

Muon HLT Meeting C. Diez

2

24-Sep-14


L2 muon trigger status report l2 seeding study

Motivation for the study

L2 Muon Trigger is already established but there may be still room for improvement optimizing the 2 step algorithm:

  • Pattern Recognition in the muon system and the tuning of the L2 parameters. http://indico.cern.ch/materialDisplay.py?contribId=2&materialId=slides&confId=53973

  • Study the L2 Seeding

    • Vector values : Evaluate pt, h, f at IP and second station

    • Errors : Study L1 resolution, compared to the default errors given in the seeding

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

Tests on L2MuonSeedGenerator

  • /RelValZMM/CMSSW_3_1_0_pre3_STARTUP_30X_v1/GEN-SIM-DIGI-RAW-HLTDEBUG (9000 evts) Rerun the trigger with the configuration which is implemented for CMSSW_3_1_X

  • Change L2 seed in RecoMuon/L2MuonSeedGenerator /src/L2MuonSeedGenerator.ccand check results comparing distributions of several variables (pt, eta, phi), their pulls and resolutions.

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

Comparison: variablesat Vtx-MB2

SimTracks (vtx)-SimHits(MB2)

  • At simulated level: Compare simulated pt, h, f given at the interaction point and in the second station (ZMuMu sample)

Firstapprox.: shift in pt by a constant ~2 GeV (CSC), ~3 GeV (DT),

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

Comparison pt Vtx-MB2

SimTracks (vtx)-SimHits(MB2)

pt vtx-MB2 vs pt(at vtx)

  • Check the distributions for the available “RelValSingleMuPt1000”

  • more bremmstrahlung losses at high Pt as expected

No statisticsfor Pt > 60-70GeV

Muon pt=1000GeV

Pt vtx-MB2 vs h (at vtx)

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

Changed pt seed: Effect in L2 distribution

Someexamples of pulls, Pt resolutionafterrerunningthe L2 triggerwiththe new seeds

FastStepHelix + Refitwith default pt seed

  • The effect is negligible (~0.3% in pt resolution)

  • It doesn´t seem worthy to further parametrise the shift (for this sample ZMuMu at least)

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

L2 seed Errors

Default Errors:

  • Are theyoverstimated?

  • Check L1 resolution (L1 vs sim.) and takethosevalues as seed error

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

L1 resolution

Resolution (L1-simulated) : p/pt, L, f

Error(q/pt)=0.25 /pt (1/GeV)

Error(L)=0.02 rad

Error(f)=0.03 rad

1.5 times smaller for CSC

2 times smaller

~10 times smaller

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

Effect in L2 distributions: Pulls

No ReFit

  • Same number of entries

  • Sigma changes by less 0.1%

  • Notseenanyremarkableeffect: Justtocheckseeifthischangeactuallyaffects at all, we removed the “refit” (rightplots)

  • Theeffectis a bit more visible, butstillnotimportant

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

Effect in L2 distributions: Resolution

  • Comparing resolution for the “default seeds”, changed pt and pt+new error estimation :

  • Theresolutionimproves a bit for pt and h, notforf, withthe “pt corrected”

  • Changingtheseedsaffectsspeciallyh

Muon HLT Meeting C. Diez


L2 muon trigger status report l2 seeding study

Summary

  • Changes in the seeding with the L2 optimizations (FastSteppingHelixPropagator (bigger extrap. steps), Refit to the L2 muon track) do not affect significantly the resolution (in pt, , ) nor the pulls.

  • The errors studied don´t seem to be “too overestimated”

  • For the CMSSW_3_1_X release the useful samples are only RelVal samples (ZMM, SingleMu) available, not so big statistics, relatively small pt range available

  • Would it make sense to use other samples where there could be more muons, not back to back, etc? Ie. Min bias or pp->mu+X?

Muon HLT Meeting C. Diez


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