AtlFast3: the next generation of fast simulation in ATLAS

Understand

The ATLAS experiment at the Large Hadron Collider has a broad physics programme ranging from precision measurements to direct searches for new particles and new interactions, requiring ever larger and ever more accurate datasets of simulated Monte Carlo events.

• Detector simulation with \textsc{Geant4} is accurate but requires significant CPU resources.
• Over the past decade, ATLAS has developed and utilized tools that replace the most CPU-intensive component of the simulation -- the calorimeter shower simulation -- with faster simulation methods.
• Here, AtlFast3, the next generation of high-accuracy fast simulation in ATLAS, is introduced.