While the current Belle II data acquisition (DAQ) system has proven to be reliable in the first collisions delivered since May 2018, an upgrade to increase the bandwidth of the readout system is foreseen to be deployed over the next few years for higher target luminosity SuperKEKB running. Currently, the front-end electronics (FEE) of individual subdetectors are connected to the online event building system via a unified optical link called Belle2Link, offering unidirectional data readout as well as bidirectional slow control access. The FEE data are received by high-speed link boards (HSLB) and common pipelined platform for electronics readout (COPPER) boards collecting data from up to four links, forwarding to readout PCs (ROPC), which further aggregate the data and forward the data to the event builder. It is planned to keep the Belle2Link and subsystems FEE as they are, but to replace the HSLB/COPPER (including the back-end side of Belle2link) and ROPC with an upgraded high-density system with increased throughput and processing capabilities, to enable the operation at higher rates. This article presents a solution for this upgrade based on the xTCA-for-Physics (MicroTCA)-compatible concentration preprocessing and fan-out plus (CPPF+) board featuring significant data concentration and processing power, providing up to 40-Gb Ethernet output bandwidth. Belle2Link back-end firmware and subevent building are implemented in the CPPF+ board to deliver equivalent functionality as the COPPER/ROPC. The MicroTCA platform provides scalability, reconfigurability, and reliable operations, even for a future possible increase in bandwidth and potential FEE upgrades. A fully functional demonstration readout system has been constructed and verified with the time-of-propagation (TOP) detector front-end test bench set up at KEK in terms of functionality as well as performance. Results show that this solution fulfills the requirements of the DAQ upgrade and works stably and reliably in long-term tests.

中文翻译：

---

用于 Belle II 实验的 DAQ 升级解决方案

虽然当前的 Belle II 数据采集 (DAQ) 系统已在 2018 年 5 月以来交付的第一次碰撞中证明是可靠的，但预计未来几年将部署升级以增加读出系统的带宽，以获得更高的目标光度 SuperKEKB跑步。目前，各个子探测器的前端电子设备 (FEE) 通过称为 Belle2Link 的统一光链路连接到在线事件构建系统，提供单向数据读出以及双向慢速控制访问。FEE 数据由高速链路板 (HSLB) 和电子读出通用流水线平台 (COPPER) 板接收，从多达四个链路收集数据，转发到读出 PC (ROPC)，后者进一步聚合数据并转发数据到事件构建器。计划保持 Belle2Link 和子系统 FEE 不变，但将 HSLB/COPPER（包括 Belle2link 的后端侧）和 ROPC 替换为具有更高吞吐量和处理能力的升级后的高密度系统，以实现以更高的速率运行。本文介绍了一种基于 xTCA-for-Physics (MicroTCA) 兼容集中预处理和扇出增强 (CPPF+) 板的升级解决方案，该板具有显着的数据集中度和处理能力，可提供高达 40 Gb 的以太网输出带宽。Belle2Link 后端固件和子事件构建在 CPPF+ 板中实现，以提供与 COPPER/ROPC 等效的功能。MicroTCA 平台提供可扩展性、可重新配置性和可靠的操作，即使未来可能增加带宽和潜在的 FEE 升级。已经构建了一个功能齐全的演示读出系统，并通过在 KEK 设置的传播时间 (TOP) 检测器前端测试台在功能和性能方面进行了验证。结果表明，该方案满足数据采集升级的要求，在长期测试中运行稳定可靠。