Demonstration of track reconstruction with FPGAs on live data at LHCb

Abstract

The LHCb experiment is currently taking data with a completely renewed DAQ system, capable for the first time of performing a full real-time reconstruction of all collision events occurring at LHC point 8. The Collaboration is now pursuing a further upgrade (“LHCb Upgrade-II”), to enable the experiment to retain the same capability at luminosities an order of magnitude larger than the maximum planned for the current Run3. To this purpose, a vigorous R&D program is ongoing to boost the real-time processing capability of LHCb, needed to cope both with the luminosity increase and the adoption of correspondingly more granular and complex detectors. New heterogeneous computing solutions are being explored, with the aim of moving reconstruction and data reduction to the earliest possible stages of processing. In this talk, we describe the results obtained from a realistic demonstrator for a high-throughput reconstruction of tracking detectors, operating parasitically on real LHCb data from Run3 in a purposely-built testbed facility. This demonstrator is based on a extremely parallel, “Artificial Retina” architecture, implemented in commercial, PCIe-hosted FPGA cards interconnected by fast optical links, and encompasses a sizeable fraction of the LHCb VELO pixel detector. The implications of the results in view of potential applications in HEP are discussed.