The ATLAS Monte Carlo tuning system

The ATLAS experiment moved the tuning of the underlying event and minimum bias event shape modeling, previously done in a manual fashion, to the automated Professor tuning tool, employed in connection with the Rivet analysis framework, when the first corresponding experimental analysis from LHC became available. The tuning effort for the Pythia 8 generator, which includes improved models for diffraction, has been started in this automated way in ATLAS, with the aim of getting a good description of the pile-up generated by multiple minimum bias interactions. The first results for these Pythia 8 tunes, as well as Pythia 6 shower tunes are presented, including a study of tunes for various PDFs.