First Name Matthew
Last Name Tamsett



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Matthew Tamsett

matt1.jpg ATLAS2.jpg SPA51634a.JPG SPA52036.JPG

Presentations 2009

To Do list


Draft plans (for medium term) + plots;

Overall aim; Discover reason for differences between SU3 and Z->ee electron trigger efficiencies. Datasets needed (overall): ttbar, SUX(3), Z->ee, Z->ee +jets (this isn't available in rel.13 (resimulate ourselves?)

Out of the possible sources, our main candidates:

  • Different event topology
  • Differences coming from different Et, eta... distributions, might be solved with a more careful average?
  • Differences affecting isolation criteria (or other trigger selection cuts)
  • Are jets faking offline electrons in the SU3 sample being the trigger less efficient for them?


  1. Investigate SUSY truth distributions
  2. Investigate truth matching to reco electrons and effect on efficiencies
  3. Investigate correlations between variables and events that pass(fail) the trigger
  4. look in low pass features (due to offline reco issue where we see two electrons very close in eta/phi with different cluster Ets) (this is the electrons which appear in the L2 normalised to L1 and EF normalised to L2 where we appear to have electrons passing the trigger with Pts below threshold.

Details i) talk to 'truth expert' (till?) about how to match to truth. (much quicker than teaching myself) --also needed for ii) plot - true e - eta, phi, Et etc... deltaR from jet, Pt of closest Jet etc. ii) understand truth matching. efficiences before and after matching (redefine control sample), also true variables of those matched reco electrons that fail trigger - true mothers of e that fail/pass trigger iii) E, Et, phi etc of closest jet in pass(fail) electrons, pass(fail) eta vs e of closest jet, E vs delta R of closest jet - correlations between eta and Et, E and eta, selection cuts vs Et, eta and selection cuts (cuts vs cuts will take longer) - look into efficiencies as a function of dR from nearest jet (with Pt above some threshold), and some measure of hadronic activity such as Meff iv) associate to trigger in deltaR and delta Et (long term), error counters and deltaR, Et, eta phi distributions etc.


To be completed are in Red

Following discussion with Teresa my plans are as follows;

What i'd like to be able to show at the SUSY meeting on 21st May

  • Susy electron trigger efficiencies with the following plots:
      • A few of the most interesting triggers for a highish luminosity scenario (say e25i and e25)
      • efficiency as a function of
      • Eta
      • Phi
      • PT
      • Other relavent variables such as distance of electron from jet, number of nearby objects etc

  • Comparison of these to Z->ee tag and probe distributions
      • Whole Z->ee sample
      • if disagreement is seen in the whole sample, due to some dependence on closeness of jets then a more appropriate sample can be used. (to be determined if such issues occur)

This is the end result, but in order to validate this the following plots will be needed;

  • Method validation vs some independent trigger efficiency determining method.

  • Plots of all trigger variables seen in ROIs that pass triggers and comparisons to expected distributions.
      • to do this for cases when more than one track of ev object are seen in the ROI have been planned for but not yet implemented. Coding of this method should take an afternoon.
      • adding the histograms should take a day or so. These can then be studied.
  • Characterization of SUSY samples to determine which variables may affect the trigger
      • so plots of the trigger cut variables will be produced along with electron Pt, Jet number, delta R between jets and electron etc
      • and comparison of this to the Z->ee sample. This should help if any discrepancy is seen between the trigger efficiencies in each sample

Note; What definition of SUSY sample should be used, my first idea would be to implement the CSC note cuts for the 3, 2 and 1 lepton analysis and look at the characterizations and trigger efficiencies seen after each analysis.

My Trigger Decision Tool status;

  • Validated vs Orthogonal trigger decision method.
  • All single electron triggers are included.
  • All objects and trigger variables are stored with the following exceptions;
      • Multiple L2 tracks and multiple objects per EF container.
      • short term solution store highest Pt object (1 hour)
      • medium term, store all and analysis for differences. (1 afternoon)
      • long term, inquire with L2 and EF trigger experts (some of this is already in progress), to determine final solution. (no idea how long this will take)
  • More counters and validation histograms must be added (eta; one afternoon)

nTuple analysis Status;

  • pyroot analysis tools are setup to;
      • validate my trig decision tool
      • apply susy cuts
      • perform tag and probe analysis
      • compare tag and probe to susy eff for Pt eta and phi

My proposed timeline; Add short or medium term solution to multiple objects, and possible add automated validation vs independent method tool then submit jobs to the grid to give results for Z->ee, SU3 and ttbar. This should be done this afternoon and the samples should be available tomorrow. Then perform a quick analysis with my nTuple tools to get an idea of how tag and probe on z->ee compares to SUSY. Then begin characterization of SUSY sample.

My Analysis

This section will contain a logbook of my work. More complete write ups can be found in linked wiki pages.

April 2008

Producing nTuples from AODs that contain Electron trigger information using the TrigDecisionTool

TrigDecisionTool, Trigger Aware Analysis in v13 (under construction)

Python based Athena and ROOT Analysis

PythonAnalysis, Python based Athena and ROOT Analysis

Z->ee, Tag and Probe Analysis

Example SUSY Analysis

My Links

My Plots

My Personal Data

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-- MatthewTamsett - 08 Apr 2008

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Topic revision: r25 - 28 May 2009 - MatthewTamsett

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