Streaming-readout data acquisition and processing system developed by SPADI Alliance

Modern nuclear physics experiments demand data acquisition systems capable of handling rapidly increasing event rates, complex detector configurations, and stringent timing requirements. Conventional trigger-based DAQ architectures suffer from dead time, limited scalability, and reduced flexibility, which restrict their applicability to next-generation high-rate measurements. To address these challenges, the SPADI Alliance was established to develop a standardized and sustainable streaming-readout data acquisition framework for nuclear physics experiments. This paper presents the concept, architecture, and performance of the streaming-readout data acquisition and processing system developed by the SPADI Alliance. The system integrates continuous-readout front-end electronics, high-precision time synchronization, scalable network-based data flow, and modular online and offline processing frameworks. Performance evaluations demonstrate more than a 40-fold improvement in achievable event rates compared to conventional systems, along with sustained data throughput exceeding 1 GB/s. Applications at RCNP and J-PARC confirm stable operation and adaptability to diverse experimental conditions. The SPADI framework provides an efficient and extensible solution for future high-intensity experiments and represents a significant step toward global standardization of data acquisition systems in nuclear physics.