PESAsim : A PESA simulation tool to for fast validation and tuning.

  • PESAsim is the name for the new "eGamma" framework. It has been developed as a fast simulation of the PESA event selection algorithms and steering to allow fast prototyping of algorithms and their validation, and to allow automatic, iterative tuning strategies.
  • Internally, the event data structure closely resembles that used online in the trigger to enable fast transfer of algorithms without too much recoding.
  • The framework itself, simulates the behaviour of the online steering, and can be used for ensembles of trigger signatures, including complete trigger menus, and multiple object triggers.


  • PESAsim developed as a replacement for the old root eGamma framework, however, to achieve the correct functionality, in terms of event selection and rejection for general use a minimal simulation of the steering was implemented.
  • The framework is not limited to the simulation of eGamma signatures and hypotheses algorithms, hence the name change.
  • In principle, given the necessary implementation of the relevant selection algorithms, there is no reason why PESAsim should not be able to implement a reasonably code simulation of a complete set of ATLAS trigger menus.


  • A (developing) user manual is available here.
  • Doxygen documentation of the code, and classes is available here.
  • code viewable in cvsview

Getting Started

Download the source code, it is available:

  • from the ATLAS cvs repository (temporarily) under Trigger/TrigAnalysis/TrigEgammaAnalysis/*/PESAsim the plan is to move it to a package of its own in the near future
  • as a tarball from here
  • or under afs at /afs/

Untar the package, go to the src directory and type

  • make install

This creates the rest of the directory structure and builds the libraries and a test executable.

The project contains the directories

  • config config files needed for execution
  • examples example projects
  • exe executables are built here
  • lib libraries
  • obj object code
  • src source code

The examples directory has example projects for various purposes, eg simple evaluation, automated fitting and so on.

Good luck!!

-- MarkSutton, RicardoGoncalo - 24 Jan 2006

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Topic revision: r8 - 2006-02-13 - RicardoGoncalo
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