Information related to Z counting to determine ATLAS luminosity

ATLAS ZCounting twiki -
ATLAS Luminosity Group -
Source code -
Luminosity for Physics -
ATLAS Lumi Calculator -
Activate Cernbox. Then accessible via /eos/user/m/miokeefe/ for example -

Example Job

Example job can be found in:

See README for description of directory and code structure.

MC samples

Special high mu Zmumu


Standard MC16a samples (matching 2015+2016 data)



Standard MC16c samples (matching 2017 data) [Now Redundant]



Standard MC16e samples



Running over MC

Same as on ZCounting twiki above, however only the script can be run. The luminosity cannot be computed, only the efficiencies.

Trigger info


Idea is:
  • Use the 2016 example run (304008) and monitor all steps (e.g. T&P efficiency) versus LB.
Long term goal is:
  • Understand syst uncertainties in Z counting related to muons, which are:
    • T&P: stats dominated, need proper treatment to avoid double counting of stats errors.
    • Muon calibration.
    • Alignment L time-dependent? Some alignment is done already in calibration loop before full data processing - sufficient?
Tasks / ongoing investigations:
  • Last update: January 29, 2018 (after discussion with Peter Onysi at CERN)
  • Understand the cuts applied: isolation, pT, eta, impact parameter cuts - nominal selection so far should be pT>27 GeV, |eta|<2.4 for both muons (can we find these selections in the code?), may need to raise pT cuts for 2018 depending on lowest unprescaled triggers available
  • Which efficiencies are applied: trigger, muon reconstruction; should aim to monitor also track efficiency and consider making T&P efficiency differential
  • How are those efficiencies calculated: Monitor and plot those efficiencies for an example run for learning - see slides by Harry, excursions are likely low statistics bins where also background subtraction carries large uncertainties (and may lead to efficiency > 1? - to be checked)
  • Where is MC used for corrections:
    • this should be part of the mu-dependent "MC non-closure" (this encapsulates all effects we cannot determine purely from data, thus "non-closure" may be somewhat misleading) -- however seems this is "correcting" back to total cross section mll>60 GeV, not useful for fiducial cross sections (and maybe not ideal to compare "fiducial Zs with CMS")
    • To investigate: QED FSR is properly taken into account, find place where truth-level selection is performed, run MC (technical hurdle: many "duplicated" histograms created when running on MC, need to run small pieces and learn how to merge this efficiently - Michael with test the command "DQ histogram merge")
  • How (if at all) are mu corrections applied: implicitly in T&P efficiencies, mu-dependend "MC non-closure"
  • Where is official lumi coming from in the plot, and is it really the latest one?
  • Implement procedure to control that all events (lumi blocks) were processed (or alternatively correct expected luminosity accordingly) - missing pieces in Michael's plots got filled on rerunning jobs on the grid
  • Usage of GRL: typically will run with a very preliminary GRL from the beginning and then later with the official GRL for the final result
  • Understand the used "acceptance" (0.3323) and theoretical Z cross section
  • Fine tuning:
    • understand if assumption SameSign events = Opposite Sign background is justified
    • is there a correlation of statistical errors of reconstruction and trigger efficiencies?


Times not available for meeting

  • Mon - 1-3 pm
  • Tue - 2-5 pm
  • Wed -
  • Thur - 11-1 pm
  • Fri - 9-11 am
  • Tue 9am - 5 pm most weeks
  • Wed 1.30pm-4pm most weeks
  • Fri 1pm-3pm
  • Tuesday 9am-12
  • Thursday 10am-5pm (Starting Week 7)



Contributors: Michael O'Keefe, Harry Lyons, Uta Klein, Jan Kretzschmar, Max Klein

-- JanKretzschmar - 12 Jan 2018
Topic attachments
I Attachment Action Size Date Who Comment
ZLumi Meeting - 19.01.18.pptxpptx ZLumi Meeting - 19.01.18.pptx manage 2 MB 19 Jan 2018 - 10:56 MichaelOKeefe Slides from today (Michael)
ZLumi_Harry_19012018.pdfpdf ZLumi_Harry_19012018.pdf manage 194 K 19 Jan 2018 - 15:56 HarryLyons Meeting Slides (Harry)
ZLumi_Harry_20022018.pdfpdf ZLumi_Harry_20022018.pdf manage 1 MB 20 Feb 2018 - 15:41 HarryLyons Summary Slides (14/02/2018 - 20/02/2018)
Topic revision: r18 - 12 Sep 2018, HarryLyons
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