Performance of the CMS Level-1 Trigger

TL;DR

This paper evaluates the performance of the CMS Level-1 trigger system, which filters collision events at the LHC to manage data rates amid increasing luminosity, ensuring efficient detection of interesting physics events.

Contribution

It provides an assessment of the CMS Level-1 trigger performance during 7 and 8 TeV collisions, highlighting its effectiveness amidst rising data rates and luminosity.

Findings

Trigger rates meet the required thresholds.

High efficiency for key physics objects.

Robust performance at increased luminosity.

Abstract

The first level trigger of the CMS experiment is comprised of custom electronics that process data from the electromagnetic and hadron calorimeters and three technologies of muon detectors in order to select the most interesting events from LHC collisions, such as those consistent with the production and decay of the Higgs boson. The rate of events selected by this Level-1 trigger must be reduced from the beam crossing frequency to no more than 100 kHz further processing can occur, a major challenge since the LHC instantaneous luminosity has increased by six orders of magnitude since the start of operations to more than 6E33 cm-2s-1 today. The performance of the Level-1 trigger, in terms of rates and efficiencies of the main objects and trigger algorithms, as measured from LHC proton collisions at 7 and 8 TeV center-of-mass energies is presented here.