Design of Time-to-Digital Converters for Time-Over-Threshold Measurement in Picosecond Timing Detectors
Design of Time-to-Digital Converters for Time-Over-Threshold Measurement in Picosecond Timing Detectors
复制标题
DOI：
10.1109/tns.2021.3060069
复制
发表时间：
2021-04
影响因子：
1.8
通讯作者：
Bo Wu;Yonggang Wang;Qiang Cao;Ziwei Li;Xin Li;Xiaoyu Zhou;Yang Hu;Zeyu Wang;M. Shao;Jianbei Liu;Cheng Li;Zhengguo Zhao
中科院分区：
文献类型：
--
作者：
Bo Wu;Yonggang Wang;Qiang Cao;Ziwei Li;Xin Li;Xiaoyu Zhou;Yang Hu;Zeyu Wang;M. Shao;Jianbei Liu;Cheng Li;Zhengguo Zhao
在皮秒级定时探测器中，通常需要测量探测器信号的过阈值时间（TOT），以提高前沿定时精度。这些探测器信号的极窄脉冲宽度对基于现场可编程门阵列（FPGA）的用于TOT测量的时间数字转换器（TDC）的设计提出了挑战。提出了一种基于FPGA的抽头延迟线（TDL）型TDC，用于同时测量核脉冲的到达时间和TOT时间。通过沿着单个TDL传播命中信号，所提出的防泡编码方案可以在一次测量中提取命中信号的两个转变的时间信息。证明了最小可测TOT时间仅受FPGA低压差分信号（LVDS）接收器的电气特性的限制。通过对采用Virtex Ultrascale + FPGA的样机进行性能评估，最小可测TOT时间可低至370 ps，TOT时间测量的均方根精度达到3.0 ps。给定的脉冲宽度范围从0.4到1.5 ns，测得的TOT时间是高度一致的直接读出值从示波器在很宽的温度范围。为了将TDC应用于基于微通道板光电倍增管（MCP-PMT）的定时检测器中，构建了具有双阈值TOT测量的前端电子板。联合束流测试结果表明，两个相同探测器通道的符合时间分辨率可从36.5 ps提高到10.3 ps，这表明了TOT测量对现代皮秒定时探测器的重要意义。
In picosecond timing detectors, the time over threshold (TOT) of detector signals is normally required to be measured to enhance the front-edge timing precision. The extremely narrow pulsewidth of these detector signals has posed challenges to the design of time-to-digital converters (TDCs) based on field programmable gate arrays (FPGAs) for TOT measurement. In this article, an FPGA-based tapped-delay-line (TDL)-type TDC is proposed to simultaneously measure the arrival time and TOT time of nuclear pulses. By propagating the hit signal along a single TDL, the proposed bubble-proof encoding scheme can extract the time information of two transitions of hit signal in one measurement. The minimum measurable TOT time is proved to be limited only by the electrical characteristics of low-voltage differential signaling (LVDS) receivers of FPGAs. Through the performance evaluation on the prototype with a Virtex Ultrascale + FPGA, where the minimum measurable TOT time can be as low as 370 ps, the rms precision reaches 3.0 ps for TOT time measurement. Given the pulsewidths ranging from 0.4 to 1.5 ns, the measured TOT time is highly consistent with the direct readout values from the oscilloscope in a wide temperature range. To apply the TDC into a microchannel plate photomultiplier tube (MCP-PMT)-based timing detector, the front-end electronics board with a dual-threshold TOT measurement is constructed. The joint beam test results show that the coincidence time resolution of two identical detector channels can be improved from 36.5 to 10.3 ps, which demonstrates the significance of TOT measurement to modern picosecond timing detectors.