CERN Accelerating science

ATLAS Slides
Report number	ATL-SOFT-SLIDE-2017-446
Title	The new ATLAS Fast Calorimeter Simulation
Author(s)	Hasib, Ahmed (University of Edinburgh)
Corporate author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Submitted to	XXIX IUPAP Conference on Computational Physics, Paris, France, 9 - 13 Jul 2017
Submitted by	[email protected] on 07 Jul 2017
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	Fast Simulation ; Fast Calorimeter Simulation
Abstract	Producing the very large samples of simulated events required by many physics and performance studies with the ATLAS detector using the full GEANT4 detector simulation is highly CPU intensive. Fast simulation tools are a useful way of reducing CPU requirements when detailed detector simulations are not needed. During the LHC Run-1, a fast calorimeter simulation (FastCaloSim) was successfully used in ATLAS. FastCaloSim provides a simulation of the particle energy response at the calorimeter read-out cell level, taking into account the detailed particle shower shapes and the correlations between the energy depositions in the various calorimeter layers. It is interfaced to the standard ATLAS digitization and reconstruction software, and it can be tuned to data more easily than GEANT4. Now an improved version of FastCaloSim is in development, incorporating the experience with the version used during Run-1. The new FastCaloSim makes use of statistical techniques such as principal component analysis, and a neural network parametrisation to optimise the amount of information stored in the ATLAS simulation infrastructure. A first prototype is available and is being tested and validated now. ATLAS plans to use this new FastCaloSim parameterization to simulate several billion events in the upcoming LHC runs. In this talk, we will describe this new FastCaloSim parametrization.