Home > Research > Publications & Outputs > Emulating the impact of additional proton–proto...

Associated organisational unit


Text available via DOI:

View graph of relations

Emulating the impact of additional proton–proton interactions in the ATLAS simulation by presampling sets of inelastic Monte Carlo events

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • ATLAS Collaboration
Article number3
<mark>Journal publication date</mark>27/01/2022
<mark>Journal</mark>Computing and Software for Big Science
Issue number1
Number of pages35
Publication StatusPublished
<mark>Original language</mark>English


AbstractThe accurate simulation of additional interactions at the ATLAS experiment for the analysis of proton–proton collisions delivered by the Large Hadron Collider presents a significant challenge to the computing resources. During the LHC Run 2 (2015–2018), there were up to 70 inelastic interactions per bunch crossing, which need to be accounted for in Monte Carlo (MC) production. In this document, a new method to account for these additional interactions in the simulation chain is described. Instead of sampling the inelastic interactions and adding their energy deposits to a hard-scatter interaction one-by-one, the inelastic interactions are presampled, independent of the hard scatter, and stored as combined events. Consequently, for each hard-scatter interaction, only one such presampled event needs to be added as part of the simulation chain. For the Run 2 simulation chain, with an average of 35 interactions per bunch crossing, this new method provides a substantial reduction in MC production CPU needs of around 20%, while reproducing the properties of the reconstructed quantities relevant for physics analyses with good accuracy.