SMuK 2023 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 52: Invited Topical Talks II-A

T 52.1: Eingeladener Vortrag

Mittwoch, 22. März 2023, 14:00–14:20, HSZ/AUDI

Commissioning of the new LHCb trigger system — •Marian Stahl — European Organization for Nuclear Research (CERN), Geneva, Switzerland

Since 2022 the upgraded LHCb experiment uses a triggerless readout system collecting data at an event rate of 30 MHz and a data rate of 4 Terabytes/second. A software-only heterogeneous High Level Trigger (HLT) enables unprecedented flexibility for reconstruction and selections. Compared to Run2 (2015-18), the amount of data to be processed by the HLT increased by a factor 60 due to operating at five times higher luminosity and the removal of the hardware trigger. The GPU-based first stage (HLT1) reduces the event rate to 1 MHz by selections based on charged particle tracking, vertexing, photon reconstruction and lepton identification. At the CPU-based second stage (HLT2), full offline quality event reconstruction and user-friendly configuration provides the flexibility that has allowed analysts to implement more than 1500 inclusive and exclusive selection algorithms. Real-time alignment and calibration directly after HLT1 ensures best detector performance in HLT2's full event reconstruction. I will describe how LHCb's Real-Time-Analysis project addresses performance and code portability challenges associated with heterogeneous computing at this scale and how the new trigger, alongside with the upgraded detector, have been commissioned in 2022.