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The ATLAS Trigger Algorithms Upgrade and Performance in Run-2
The ATLAS trigger has been used very successfully for the online event selection during the first part of the second LHC run (Run-2) in 2015/16 at a center-of-mass energy of 13 TeV. The trigger system is composed of a hardware Level-1 trigger and a software-based high-level trigger; it reduces the e...
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Lenguaje: | eng |
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2017
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Acceso en línea: | http://cds.cern.ch/record/2286319 |
_version_ | 1780955970048884736 |
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author | Bernius, Catrin |
author_facet | Bernius, Catrin |
author_sort | Bernius, Catrin |
collection | CERN |
description | The ATLAS trigger has been used very successfully for the online event selection during the first part of the second LHC run (Run-2) in 2015/16 at a center-of-mass energy of 13 TeV. The trigger system is composed of a hardware Level-1 trigger and a software-based high-level trigger; it reduces the event rate from the bunch-crossing rate of 40 MHz to an average recording rate of about 1 kHz. The excellent performance of the ATLAS trigger has been vital for the ATLAS physics program of Run-2, selecting interesting collision events for a wide variety of physics signatures with high efficiency. The trigger selection capabilities have been significantly improved compared to Run-1, in order to cope with the higher event rates and pile-up during Run-2. At the Level-1 trigger the undertaken improvements resulted in more pile-up robust selection efficiencies and event rates and in a reduction of fake candidate particles. A new hardware system, designed to analyze event-topologies, supports a more refined event selection at the Level-1. A hardware-based high-rate track reconstruction is currently being commissioned. Together with a re-design of the high-level trigger to deploy more offline-like reconstruction techniques, these changes improve the performance of the trigger selection turn-on and efficiency to nearly that of the offline reconstruction. In order to prepare for the anticipated further luminosity increase of the LHC in 2017/18, improving the trigger performance remains an ongoing endeavor. The large number of pile-up events is one of the most prominent challenges. This report gives a short review the ATLAS trigger system and its performance in 2015/16 before describing the significant improvements in selection sensitivity and pile-up robustness, which we implemented in preparation for the expected highest ever luminosities of the 2017/18 LHC. |
id | cern-2286319 |
institution | Organización Europea para la Investigación Nuclear |
language | eng |
publishDate | 2017 |
record_format | invenio |
spelling | cern-22863192021-05-03T08:20:03Zhttp://cds.cern.ch/record/2286319engBernius, CatrinThe ATLAS Trigger Algorithms Upgrade and Performance in Run-2hep-exParticle Physics - ExperimentThe ATLAS trigger has been used very successfully for the online event selection during the first part of the second LHC run (Run-2) in 2015/16 at a center-of-mass energy of 13 TeV. The trigger system is composed of a hardware Level-1 trigger and a software-based high-level trigger; it reduces the event rate from the bunch-crossing rate of 40 MHz to an average recording rate of about 1 kHz. The excellent performance of the ATLAS trigger has been vital for the ATLAS physics program of Run-2, selecting interesting collision events for a wide variety of physics signatures with high efficiency. The trigger selection capabilities have been significantly improved compared to Run-1, in order to cope with the higher event rates and pile-up during Run-2. At the Level-1 trigger the undertaken improvements resulted in more pile-up robust selection efficiencies and event rates and in a reduction of fake candidate particles. A new hardware system, designed to analyze event-topologies, supports a more refined event selection at the Level-1. A hardware-based high-rate track reconstruction is currently being commissioned. Together with a re-design of the high-level trigger to deploy more offline-like reconstruction techniques, these changes improve the performance of the trigger selection turn-on and efficiency to nearly that of the offline reconstruction. In order to prepare for the anticipated further luminosity increase of the LHC in 2017/18, improving the trigger performance remains an ongoing endeavor. The large number of pile-up events is one of the most prominent challenges. This report gives a short review the ATLAS trigger system and its performance in 2015/16 before describing the significant improvements in selection sensitivity and pile-up robustness, which we implemented in preparation for the expected highest ever luminosities of the 2017/18 LHC.arXiv:1709.09427oai:cds.cern.ch:22863192017 |
spellingShingle | hep-ex Particle Physics - Experiment Bernius, Catrin The ATLAS Trigger Algorithms Upgrade and Performance in Run-2 |
title | The ATLAS Trigger Algorithms Upgrade and Performance in Run-2 |
title_full | The ATLAS Trigger Algorithms Upgrade and Performance in Run-2 |
title_fullStr | The ATLAS Trigger Algorithms Upgrade and Performance in Run-2 |
title_full_unstemmed | The ATLAS Trigger Algorithms Upgrade and Performance in Run-2 |
title_short | The ATLAS Trigger Algorithms Upgrade and Performance in Run-2 |
title_sort | atlas trigger algorithms upgrade and performance in run-2 |
topic | hep-ex Particle Physics - Experiment |
url | http://cds.cern.ch/record/2286319 |
work_keys_str_mv | AT berniuscatrin theatlastriggeralgorithmsupgradeandperformanceinrun2 AT berniuscatrin atlastriggeralgorithmsupgradeandperformanceinrun2 |