Real-time reconstruction of long-lived particles at LHCb using FPGAs

Riccardo Cenci,Michael J Morello,Federico Lazzari,Giovanni Punzi,Andrea Di Luca

doi:10.1088/1742-6596/1525/1/012101

Abstract

Finding tracks downstream of the magnet at the earliest LHCb trigger level is not part of the baseline plan of the upgrade trigger, on account of the significant CPU time required to execute the search. Many long-lived particles, such as KS 0 and strange baryons, decay after the vertex track detector, so that their reconstruction efficiency is limited. We present a study of the performance of a future innovative real-time tracking system based on FPGAs, developed within a R&D effort in the context of the LHCb Upgrade Ib (LHC Run 4), dedicated to the reconstruction of the particles downstream of the magnet in the forward tracking detector (Scintillating Fibre Tracker), that is capable of processing events at the full LHC collision rate of 30 MHz.

Highlights

The LHCb detector, collected data at a luminosity of 4 × 1032cm−2s−1 until the end of LHC Run 2
During the Long Shutdown 2 (LS2) it will be replaced by an upgraded experiment, referred as the Phase-I Upgrade (LHC Run 3, 2021-2024 and LHC Run 4, 2027-2029)
The precision on a host of important, theoretically clean, measurements will still be limited by statistics, and other observables associated with highly suppressed processes will be poorly known

Summary

Introduction

The LHCb detector, collected data at a luminosity of 4 × 1032cm−2s−1 until the end of LHC Run 2. An R&D work is currently ongoing [3], within the LHCb Collaboration, for the realization of an innovative tracking device, the so-called Downstream Tracker, capable of reconstructing in real time long-lived particles in the context of the envisioned future upgrades (beyond LHC Run 3) of the LHCb experiment, with the aim of recovering the reconstruction efficiency of the downstream tracks Such a specialized processor is supposed to obtain a copy of the data from the readout system, reconstruct downstream tracks, and insert them back in the readout chain before the event is assembled, in order to be sent to the high level trigger in parallel with the raw detector information. In order to design and realize a fully operational Downstream Tracker this challenge has to be overcome at first These proceedings present, the first study of the performance of a real-time reconstruction of T-tracks, in the SciFi subdetector, achievable with the artificial retina architecture, using fully simulated events at the LHCb Upgrade (LHC Run 3 and 4) conditions. Since the fringe magnetic field on the y − z view is very small, the same approximations used for the axial

Downstream strange

Findings

Conclusions