An Automated Bandwidth Division for the LHCb Upgrade Trigger

Timothy Evans; Conor Fitzpatrick; Joshua Horswill

doi:10.1007/s41781-025-00139-2

An Automated Bandwidth Division for the LHCb Upgrade Trigger

Timothy Evans, Conor Fitzpatrick, Joshua Horswill

Research output: Contribution to journal › Article › peer-review

Abstract

The upgraded Large Hadron Collider beauty (LHCb) experiment is the first detector based at a hadron collider using a fully software based trigger. The first ‘High Level Trigger’ stage (HLT1) reduces the event rate from 30 MHz to approximately 1 MHz based on reconstruction criteria from the tracking system, and consists of O(100) trigger selections implemented on Graphics Processing Units (GPUs). These selections are further refined following the full offline-quality reconstruction at the second stage (HLT2) prior to saving for analysis. An automated bandwidth division has been performed to equitably divide this 1 MHz HLT1 Output Rate (OR) between the signals of interest to the LHCb physics programme. This was achieved by optimising a set of trigger selections that maximise efficiency for signals of interest to LHCb while keeping the total HLT1 readout capped to a maximum. The bandwidth division tool has been used to determine the optimal selection for 35 selection algorithms over 80 characteristic physics channels.

Original language	English
Article number	7
Journal	Computing and Software for Big Science
Volume	9
DOIs	https://doi.org/10.1007/s41781-025-00139-2
Publication status	Published - 21 May 2025

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abstract = "The upgraded Large Hadron Collider beauty (LHCb) experiment is the first detector based at a hadron collider using a fully software based trigger. The first {\textquoteleft}High Level Trigger{\textquoteright} stage (HLT1) reduces the event rate from 30 MHz to approximately 1 MHz based on reconstruction criteria from the tracking system, and consists of O(100) trigger selections implemented on Graphics Processing Units (GPUs). These selections are further refined following the full offline-quality reconstruction at the second stage (HLT2) prior to saving for analysis. An automated bandwidth division has been performed to equitably divide this 1 MHz HLT1 Output Rate (OR) between the signals of interest to the LHCb physics programme. This was achieved by optimising a set of trigger selections that maximise efficiency for signals of interest to LHCb while keeping the total HLT1 readout capped to a maximum. The bandwidth division tool has been used to determine the optimal selection for 35 selection algorithms over 80 characteristic physics channels.",

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An Automated Bandwidth Division for the LHCb Upgrade Trigger

Abstract

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