ATLAS Offline Software
ATLAS Offline software

Welcome to ATLAS offline software!

To find out how to build Athena, make merge requests etc, please have a look at the release building pages.

In particular, if you fork this project please do not forget to add the ATLAS Robot as a developer (assuming you might want to submit a merge request) as documented here.

For ATLAS members, please see the Atlas Computing Twiki for even more information.


The following branches are currently active:

Branch Purpose Main Project, Release Series
21.0 Tier0 and MC16c Athena, 21.0.X
21.0-mc16a MC16a bugfixes Athena, 21.0.20.Y
21.0-mc16d MC16d bugfixes Athena, 21.0.20.Y
21.1 HLT and P1 monitoring AthenaP1, 21.1.X
21.2 Derivations and Analysis AthDerivations + (Ath)AnalysisBase, 21.2.X
21.3 MC18 Simulation Athena, 21.3.X
21.6 Event Generation AthGeneration, 21.6.X
21.9 Upgrade Phase-2 developments Athena + AthSimulation, 21.9.X
master AthenaMT development Athena, 22.0.X


  • The ATLAS webpage will tell you all about the ATLAS experiment (for ATLAS members, the collaboration webpage is here)
  • The Twiki is the main source of documentation, and has many links to sub-domains
  • The software documentation page has some tutorials etc
  • The git repository is here
  • And the Doxygen code documentation can be found here
  • To cite Athena, you can use the following zenodo DOI