摘要：
中国散裂中子源(China Spallation Neutron Source,CSNS)工程通用粉末衍射谱仪(General Purpose Powder Diffractometer,GPPD)采用闪烁体探测器作为主探测器.为满足谱仪的设计需求,读出电子学系统要求在实现高达数千通道数据读出的同时,完成高精度的中子探测.基于设计目标,以及进一步提高读出系统的集成度和灵活性,读出电子学系统采用了"子板+母板"的架构.前放子板采用专用集成电路(Application Specific Integrated Circuit,ASIC)实现探测器输出信号的放大、成形、甄别等模拟调理;母板固件采用了多级流水线机制的设计方法,在保证数据并行性和可靠性的同时,进一步减小了数据处理的死时间,实现数据的采集打包、缓存等处理,最终数据通过千兆以太网传到后端数据处理系统,便于数据的分析处理.对设计实现的读出电子学系统的评估测试结果表明:最小时间分辨11 ns,单通道计数率200 K?s?1,各项指标均好于设计目标.目前所有读出电子学单元已部署到GPPD工程现场并长期稳定运行,为谱仪顺利开展实验提供了可靠保证.%[Background] The general purpose powder diffractometer (GPPD) of China spallation neutron source (CSNS) project uses the scintillation detector as the main detector. [Purpose] In order to meet the design requirements of GPPD, this study aims to develop a readout electronics with capability of data acquisition for thousands of channels and high-precision neutron detection. [Methods] Based on the design objectives, the integration and flexibility of the readout system are implemented, and the structure of "sub-board+ mainboard" is adopted. The front amplifier board uses an application specific integrated circuit (ASIC) to realize analog signal processing such as amplification, shaping and discrimination. The motherboard firmware adopts the design method of multi-level pipeline mechanism. While ensuring the parallelism and reliability of data, the dead time of data processing is reduced, and data acquisition, packaging, caching and other processing are realized. The final data is transmitted to the back-end data processing system through Gigabit Ethernet for data analysis and processing. [Results] The evaluation results of the designed and implemented readout electronics show that the minimum time resolution is 11 ns and the single channel counting rate is 200 K?s?1, and all performance indicators are better than the design objectives. All the readout electronic units have been deployed to GPPD project site and operated stably since commissioning. [Conclusion] Successful development of readout electronics for the main detector of GPPD provides a reliable guarantee for the smooth development of the spectrometer.
