Data Acquisition System for the COMPASS plus plus /AMBER Experiment

We present a new data acquisition system for the COMPASS++/AMBER experiment designed as a further development of the intelligent FPGA-based data acquisition framework. The system is designed to have a maximum throughput of 5 GB/s. We designed the system to provide free-running continuous readout, which allows us to implement a sophisticated data filtering by delaying the decision until the hardware filter and high-level trigger stage which processes data. The system includes front-end cards, fully digital hardware filter, data multiplexers, a timeslice builder, and a high-level trigger farm. The data selection and data assembly require a time structure of the data streams with different granularity for different detectors. We define a unit of detector data as image and combine images from different detectors within a time window to timeslices. By routing data based on the timeslices, we can average data rates and easily achieve scalability. The main component that allows us to achieve these goals is a high-performance and cost-effective hardware timeslice builder. The timeslice builder combines streaming data by their time and consists of the data switch and the spillbuffer build. The scalable architecture allows us to increase the throughput of the system and achieve a true triggerless mode of operation.