arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1806.01490physics.ins-deteess.SP
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基于单FPGA的CSNS μSR谱仪32通道TDC设计

Design of 32-channel TDC Based on Single FPGA for μSR Spectrometer at CSNS

Fanshui Deng, Hao Liang, Bangjiao Ye, Jingyu Tang

摘要:

μ子自旋旋转、弛豫和共振(μSR)技术在研究材料的微结构和性能,特别是微磁性能方面具有不可替代的作用。中国空间中子源(CSNS)正在建造一个实验μ子源。与此同时,我国第一台128通道μSR谱仪正在研制中。通过拟合正电子计数率随时间的变化曲线,可以得到μSR的时间谱。本文介绍了一种用Xilinx Virtex-6现场可编程门阵列(FPGA)实现的32通道时间数字转换器(TDC),用于μSR谱仪正电子飞行时间的测量。每个通道的信号采用16个等间距移相的200 MHz采样时钟进行采样,因此TDC bin大小为312.5ps。测量范围可达327 us。该TDC具有在短时间内存储多个命中信号的能力,具有高达512的深度命中缓冲器。时间标签被添加到每个数据以记录数据被检测到的时刻。可编程的时间窗口和通道屏蔽提供了选择时间范围和感兴趣的通道的灵活性。每个通道的延迟可以校准。数据通过千兆以太网传输到数据采集系统(DAQ)。TDC和控制逻辑由DAQ实时配置。测试结果表明,单通道半高宽(FWHM)精度优于273 ps,温度敏感性低,线性度好。

英文摘要:

Muon Spin Rotation, Relaxation and Resonance (μSR) technology has an irreplaceable role in studying the microstructure and properties of materials, especially micro-magnetic properties. An experimental muon source is being built in China Spallation Neutron Source (CSNS) now. At the same time, a 128-channel μSR spectrometer as China's first μSR spectrometer is being developed. The time spectrum of μSR can be obtained by fitting the curve of positron count rate with time. This paper presents a 32-channel Time-to-Digital Converter (TDC) implemented in a Xilinx Virtex-6 Field Programmable Gate Array (FPGA) for measuring the positron's flight time of μSR Spectrometer. Signal of each channel is sampled by 16 equidistant shifted-phase 200 MHz sampling clocks, so the TDC bin size is 312.5ps. The measuring range is up to 327us. This TDC has the ability to store multiple hit signals in a short time with a deep hit-buffer up to 512. Time tag is added to each data to record the moment when the data was detected. Programmable time window and channel shielding give the flexibility to choose the time range and channels of interest. The delay of each channel can be calibrated. The data is transmitted to data acquisition system (DAQ) through Gigabit Ethernet. TDC and control logic are configured in real time by DAQ. The results of test show that the Full Width at Half Maximum (FWHM) precision of single channel is better than 273 ps with a low sensitivity to temperature and the linearity is pretty well.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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