This article describes a custom VHDL firmware implementation of a two-dimensional cluster-finder architecture for reconstructing hit positions in the new vertex pixel detector (VELO) that is part of the LHCb Upgrade. This firmware has been deployed to the existing FPGA cards that perform the readout of the VELO, as a further enhancement of the DAQ system, and will run in real time during physics data taking, reconstructing VELO hits coordinates on-the-fly at the LHC collision rate. This pre-processing allows the first level of the software trigger to accept a 11% higher rate of events, as the ready-made hits coordinates accelerate the track reconstruction and consumes significantly less electrical power. It additionally allows the raw pixel data to be dropped at the readout level, thus saving approximately 14% of the DAQ bandwidth. Detailed simulation studies have shown that the use of this real-time cluster finding does not introduce any appreciable degradation in the tracking performance in comparison to a full-fledged software implementation. This work is part of a wider effort aimed at boosting the real-time processing capability of HEP experiments by delegating intensive tasks to dedicated computing accelerators deployed at the earliest stages of the data acquisition chain.

翻译：本文描述了一种用于重建新顶点像素探测器（VELO）中击打位置的二维团簇识别架构的自定义VHDL固件实现，该探测器是LHCb升级项目的一部分。该固件已部署至现有的执行VELO读出的FPGA板卡中，作为数据采集系统的进一步增强功能，并将在物理数据采集期间实时运行，以LHC对撞频率即时重建VELO击打坐标。这种预处理使软件触发第一级能够接受高出11%的事件率，因为预制的击打坐标加速了径迹重建并显著降低了功耗。此外，它允许在读出级别丢弃原始像素数据，从而节省约14%的数据采集带宽。详细的仿真研究表明，与完备的软件实现相比，使用这种实时团簇识别不会对径迹性能造成任何明显退化。本工作是更广泛努力的一部分，旨在通过将密集型任务委派给部署在数据采集链最前端的专用计算加速器，来提升高能物理实验的实时处理能力。