Adopting new technologies in the LHCb Gauss simulation framework

Dominik Müller,A Forti,L Betev,M Litmaath,P Hristov,O Smirnova

doi:10.1051/epjconf/201921402004

Dominik Müller, A Forti + Show 4 more

Open Access

https://doi.org/10.1051/epjconf/201921402004

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Abstract

The increase in luminosity foreseen in the future years of operation of the Large Hadron Collider (LHC) creates new challenges in computing efficiency for all participating experiment. For Run 3 of the LHC, the LHCb collaboration needs to simulate about two orders of magnitude more Monte Carlo events to exploit the increased luminosity and trigger rate. Therefore, the LHCb simulation framework (Gauss) will go through a significant renovation, mostly driven by the upgraded core software framework (Gaudi) and the availability of a multithreaded version of Geant4. The upgraded Gaudi framework replaces single-threaded processing by a multithreaded approach, allowing concurrent execution of tasks with a single event as well as multiple events in parallel. A major task of the required overhaul of Gauss is the implementation of a new interface to the multithreaded version of Geant4.

Highlights

Monte Carlo samples are a crucial tool to understand and interpret the data recorded by the experiments in High Energy Physics (HEP)
A detailed simulation of the detector response, which behaves similar to nature and tracks particles traversing the various detector volumes leaving energy deposits, is very CPU intensive and accounts for large fractions of the overall CPU usage of HEP experiments
Despite the considerable investment of resources, recent measurements hinting at tensions with respect to the predictions of the Standard Model of elementary particle physics have systematic uncertainties that are dominated by the insufficient amount of simulated data [1]

Summary

Introduction — The Gauss framework

Monte Carlo samples are a crucial tool to understand and interpret the data recorded by the experiments in High Energy Physics (HEP). They allow analysers to extract physics information from recorded data by providing a means to separate detector effects and reconstruction efficiencies from genuine physical phenomena. This usually happens in a two stage process. A detailed simulation of the detector response, which behaves similar to nature and tracks particles traversing the various detector volumes leaving energy deposits, is very CPU intensive and accounts for large fractions of the overall CPU usage of HEP experiments. This paper summarises the ongoing efforts to modernise Gauss, the LHCb simulation framework

The Run 1 and 2 framework and its shortcomings

The upgraded framework

Handling of random numbers

A multi-threaded generation phase

Findings

The Geant4 interface