It is made of two steps: the Level 1 trigger, a custom-built electronics system that reduces the rate down to 100 kHz, and the High Level trigger (HLT), a software system running a light version of the offline reconstruction and made of hundreds of algorithms (“paths”). At HLT, several constraints must be considered:

Mar 6, 2014 · The CMS experiment has been designed with a 2-level trigger system: the Level 1 Trigger, implemented on custom-designed electronics, and the High Level Trigger (HLT), a streamlined version of the CMS offline reconstruction software running on a computer farm.

Feb 29, 2008 · The CMS data acquisition (DAQ) system relies on a purely software driven high level trigger (HLT) to reduce the full Level 1 accept rate of 100 kHz to approximately 100 Hz for archiving and later offline analysis.

At CMS, the High Level Trigger (HLT) is responsible for analysing in real time up to 100’000 collision events per second, and selecting the most highly energetic, rare or otherwise interesting ones for permanent storage and offline analysis.

We present a candidate trigger menu for a start-up luminosity of 1032cm−2s−1. A realistic HLT input event variety is obtained by using the Level-1 trigger emulator on the very large QCD backgrounds, a mixture of heavy-quark and vector boson decays to leptons.

Jun 1, 2006 · In this review we present in detail prototype CMS HLT physics selection algorithms, expected trigger rates and trigger performance in terms of both physics efficiency and timing.

Dec 1, 2015 · The CMS High Level Trigger (HLT) is a collection of software algorithms that run using an optimized version of the CMS offline reconstruction software. The HLT uses Python configuration files each containing hundreds of "modules", organized in "sequences" and "paths".

At the Compact Muon Solenoid experiment the original collision rate is reduced by a factor of O (1000) using a Level-1 hardware trigger. A subsequent factor of O (1000) data reduction is obtained by a software-implemented High Level Trigger (HLT) selection that is executed on a multi-processor farm.

At the start of Run-3 in 2022, the Compact Muon Solenoid (CMS) experiment at CERN will deploy a High Level Trigger (HLT) farm composed of 200 dual processor servers, each equipped with two AMD EPYC “Milan” 7763 CPUs and two NVIDIA Tesla T4 GPUs.

Jun 8, 2021 · The CMS experiment at the LHC selects events with a two-level trigger system, the Level-1 (L1) trigger, and the high-level trigger (HLT). The HLT reduces the rate from 100 to about 1 kHz and has access to the full detector readout and runs a streamlined version of the offline event reconstruction.