Fake MET - PowerPoint PPT Presentation

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Fake MET

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From Song Ming Wang: Joint D0/CDF/CMS Jet/MET Workshop, Jan 28th 2004 ... Just a preliminary, qualitative look at what is seen in the detector ... – PowerPoint PPT presentation

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Title: Fake MET


1
Fake MET
  • Noisy channels
  • Online/offline strategies
  • Non-collision backgrounds
  • Beam halo
  • Beam loses
  • Cosmics

Hot channels
From Song Ming Wang Joint D0/CDF/CMS Jet/MET
Workshop, Jan 28th 2004
2
First Look at Beam Halo Muons in CMS
(see B. Scurlocks talk, CMS Week, March 2005)
  • Just a preliminary, qualitative look at what is
    seen in the detector
  • No rates or cross-sections calculated
  • No overlay with pile-up
  • Used 6000 events (out of 8000) from Beam Halo
    Muon samples generated by Volker Drollinger for
    his studies
  • CMKIN_4_2_0, OSCAR_3_6_5
  • Digitised privately at Florida using ORCA_8_7_1
  • Looked at
  • Stand Alone Muon Reconstructor (default)
  • Iterative Cone Jets, R 0.5 (default)
  • MET and Sum ET from EcalPlusHcalTowers (default)

3
Beam Halo Muon Distributions First Look
(see B. Scurlocks talk, CMS Week, March 2005)
  • Qualitatively what one expects
  • MET
  • End-cap Muons
  • Barrel Jets
  • Even at low lumi, nearly every beam halo is
    overlaid with collisions (e.g. 3.5 non-diff
    collisions for L2x1033)
  • Next step - Develop MET cleaning algorithms
  • Form rejection criteria based on ECAL vs. HCAL
    energy

5999 events
EcalPlusHcalTowers
Sum ET
MET
Why so large? Investigating!
81 events
STA Muon ?
IC5 Jet ET
861 events
IC5 Jet ?
4
Plan
  • Develop MET Cleaning tools/algorithms/strategies
  • Useful for early physics
  • Overlay beam halo simhits with cosmic simhits
    with minbias simhits and digitise with ORCA
  • Individually and all together
  • use PU code developed by Heavy Ion Group
  • Do for a variety of beam halo rates

5
Plan (cont.)
  • Study effect of beam halo cosmic muons on
    trigger rates
  • Study various cleaning algorithms (currently
    inspired from CDF D0). E.g.
  • Event charged fraction
  • Event EM fraction
  • Narrow longitudinal strip of hit HCAL towers
    (constant in phi)
  • Aiming for
  • CMS Note for September
  • Contributed JetMET Section in P-TDR Vol. 1

6
Future
  • Investigate how MET might be used in online Data
    Quality Monitoring
  • Etc,
  • etc
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