用于像素探测器的高事例率高精度TDC ASIC原型电路的设计与仿真

像素探测器因其优异的位置分辨能力在高能粒子物理实验的内径探测器中有着广泛应用,随着应用场景的发展,许多物理实验要求探测器及其读出电子学也具备高精度时间测量的能力。针对像素探测器时间测量的需求,设计完成了一款具备高事例率处理能力、高精度特点的TDC(Time-to-Digital Conversion) ASIC(Application Specific Integrated Circuit) 原型电路,将来可以作为核心组成部分集成到像素探测器前端读出ASIC中。采用粗细结合的方案完成TDC的设计,其中粗时间测量基于计数器实现,细时间测量采用TAC(Time-to-Amplitude Converter)结合ADC(Time-to-Amplitude Converter)的结构实现,基于130 nm工艺完成了原型电路的设计。对TDC进行仿真,仿真结果表明,该电路可以最多处理连续11个事例,相邻事例的最短时间间隔为500 ps,bin size达到了2 ps,DNL(Differential Non-Linearity)小于2.8 ps,时间测量精度好于5 ps RMS。     

An analogue front-end ASIC prototype designed for PMT signal readout

The Water Cherenkov Detector Array(WCDA) is one of the core detectors in the Large High Altitude Air Shower Observatory(LHAASO),and it consists of 3600 photomultiplier tubes(PMTs).Both high resolution time and charge measurement are required over a large dynamic range from 1 photoelectron(P.E.) to 4000 P.E.The prototype of an analogue front-end Application Specific Integrated Circuit(ASIC) fabricated using Global Foundry 0.35 μm CMOS technology is designed to read out the PMT signal in the WCDA.This ASIC employs leading edge discrimination and an(RC)~4 shaping structure.Combined with the following Time-to-Digital Converter(TDC) and Analog-to-Digital Converter(ADC),both the arrival time and charge of the PMT signal can be measured.Initial test results indicate that time resolution is better than 350 ps and charge resolution is better than 10% at 1 P.E.and better than 1% with large input signals(300 P.E.to 4000 P.E.).Besides,this ASIC has a good channel-to-channel isolation of more than 84 dB and the temperature dependency of charge measurement is less than 5% in the range 0-50°C.     

超短光脉冲的单延迟三次相关测试

超短光脉冲的对称性可以用单延迟三次相关测试来测定,若再与二次相关测试所得的结果进行比较,可以得到更多的关于脉冲形伏的信息,经测定,Nd:YAG被动锁模激光器的脉冲形状可近似认为高斯-指数形,三次相关函数宽度为22.3ps+15.7ps,对应脉冲宽度为27ps,脉冲的前沿陡于后沿。 关键词：     

DHR TDC芯片的性能测试

TDC(time-to-digital converter)作为基于信号甄别和时间数字转换的时间测量技术路线的主要组成部分之一,至今在诸多领域中都具有广泛的应用.本实验室对高精度时间测量TDC ASIC(Application Specific In-tegrated Circuit)进行了深入研究,在180nm CM...     

A study of time over threshold (TOT) technique for plastic scintillator counter

A new charge measurement method, time over threshold (TOT), has been used in some gas detectors lately. Here TOT is studied for TOF system, made of plastic scintillator counter, which can simplify the electronics of the system. The signal characteristics are measured and analyzed with a high quality oscilloscope, including noise, pedestal, signal amplitude, total charge, rise time and the correlation between them. The TOT and charge are related and can be fitted by some empirical formula. The charge measurement resolution by TOT is given and this will help the design of TOF electronics.     

基于SCA ASIC的高精度时间测量原型电子学设计

基于高速波形数字化实现高精度时间测量是核与粒子物理实验读出电子学中的研究热点。本工作针对高精度时间测量的需求基于实验室自主研发的开关电容阵列(Switched Capacitor Array, SCA)专用集成电路(Application Specific Integrated Circuit,ASIC)开展16通道集成的时间测量电子学原型的设计,输入信号经过SCA采样和量化后传输至现场可编程逻辑阵列(Field Programmable Gate Array, FPGA),在FPGA中进行误差修正、时间内插和数字甄别提取出时间信息。目前已在实验室环境下完成此电子学的时间精度测试,测试结果表明,此电子学可以实现好于10 ps RMS(Root Mean Square)的时间精度。     

Studies of timing properties for a TOF counter at an external target facility

Timing and amplitude properties of a prototype scintillator TOF counter at an external target facility are studied with a cosmic rays test. The dependence of signal pulse height and time resolution on the coordinate along the scintillator TOF counter is investigated with two different discriminators. A time resolution of 165 ps can be achieved at the center of the counter with a constant fraction discriminator. Time resolution better than 150 ps is obtained at the center with a leading edge discriminator after time walk correction is applied for off-line analysis.     

Studies of timing properties for a TOF counter at an external target facility

Timing and amplitude properties of a prototype scintillator TOF counter at an external target facility are studied with a cosmic rays test. The dependence of signal pulse height and time resolution on the coordinate along the scintillator TOF counter is investigated with two different discriminators. A time resolution of 165 ps can be achieved at the center of the counter with a constant fraction discriminator. Time resolution better than 150 ps is obtained at the center with a leading edge discriminator after time wall（ correction is applied for off-line analysis.     

脉冲激光测距时间间隔测量技术

在脉冲激光测距系统中,为提高时间间隔测量的精度,采用插值法进行时间间隔测量。在分析传统的数字计数法测量原理与误差的基础上,重点研究了插值法。其测量对象针对传统数字计数法中待测脉冲上升沿与下一个量化时钟脉冲上升沿之间的时间间隔。测量采用电容充放电技术,把时间间隔加入到一个时间扩展模块(通常为一只高精度的电容),实现时间上的放大,再对放大后的时间进行测量,可提高时间测量的精度。利用该方法得到的时间间隔测量精度可达到100 ps,对应于1.5 cm的测距精度。     

BESⅢ TOF前端读出电子学系统原型设计和实验结果

作为北京谱仪(Beijing Spectrometer, 简称BES)的改造, BESⅢ将把TOF(time-of-flight)测量精度提高到一个新的水平, 总时间分辨不大于90ps. 其中要求前端电子学(Front End Electronics, FEE)对时间测量的不确定性贡献小于25ps. 本文介绍了TOF前端读出电子学系统原型电路的设计和初步的测试结果.     

中国散裂中子源反角白光中子源T0信号的精确扇出方法

反角白光中子源位于中国散裂中子源(CSNS),是以不同中子能量下的核数据测量为目标的大型物理实验装置,中子的能量是通过中子飞行时间(TOF)来获取的.实验中,将质子束流轰击钨靶的时刻作为TOF的起始时刻(T0),相应的电子学信号被用于触发整个电子学系统的运行.为了保证TOF测量的准确性和电子学系统各通道采集的同步性,需...     

皮秒电脉冲的产生,测量及在微带中的传输色散

本文描述了Ｃｒ：ＧａＡｓ－ＬｉＴａＯ３开关－行波普克尔盒的设计结构。用飞秒激光脉冲作激发、探针脉冲，采用电光采样技术，产生并测量到了上升沿约为５ｐｓ的超快电脉冲，并从Ｙａｍａｓｈｉｔａ的微带设计方程出发，运用准ＴＥＭ波近似，分析了微带线的色散特性及ｐｓ电脉冲在微带中传播时的波形畸变，电脉冲较陡的上升沿在传播过程中被展宽而下降沿变陡。     

新型涂硼热中子MWPC探测器的时间信号读出方法

基于10B薄膜的二维灵敏探测器是新近发展起来的热中子探测器,其灵敏面积大,时间和位置分辨好,n/抑制能力高,抗辐射能力强,可二维读出且具有良好的耐计数能力。针对新型的涂硼灵敏热中子多丝正比（MWPC）探测器,在延迟线时间差方法的基础上,提出一种中子击中位置数字信息的读出方法,并设计NIM读出插件用以验证该方法对于二维中子探测位置信息的读出能力。测试结果表明,本方法能完成4通道探测器信号的实时测量,其时间测量精度好于50 ps。结合FPGA片上系统实时数据控制和处理技术,单插件可支持最高1.3MHz的探测计数率。     

一种改进式TAC的高精度时间间隔测量系统的实现

设计了一种基于改进式时间-幅度转换器(Time-Amplitude Converter, TAC)的高精度时间间隔测量系统。该系统采用集成运放设计TAC中的电流可控的恒流源,并对TAC内部的积分控制部分加入宽带直流放大电路,来提高时间间隔测量的精确度;采用高精度的模数转换器采样TAC的输出,实现高精度时间间隔测量中的模拟到数字的转换;采用现场可编程逻辑门阵列(Field Programmable Gate Array, FPGA)完成系统软件设计,实现对TAC的控制。通过变换TAC的采样电阻的阻值,使恒流源输出不同的电流对电容进行充电,从而使TAC的输出电压满足高精度模数转换器(Analog-Digital Converter,ADC)采集电压的要求。实验表明,在测量时间范围为1us,800ns,400ns,200ns时,该系统的时间间隔测量的最小时间精度为400皮秒。     

Super-High Resolution Time Interval Measurement Method Based on Time-Space Relationships

Based on the principle of quantized delay-time, a super-high resolution time interval measurement method is proposed based on time-space relationships. Using the delay-time stability that time and frequency signal travel in a specific medium, the measured time interval can be quantized. Combined with the phase coincidence detection technique, the measurement of time can be changed into the measurement of space length. The resolution and the stability of the measurement system are easily improved. Experimental results show that the measurement resolution of the measured time interval depends on the length difference of the double delay-time unit. When the length difference is set up on millimeter level or sub-millimeter level, super-high measurement resolution from hundreds of picosecond to tens of picosecond can be obtained.     

频域反射法光纤延时精密测量

本文提出了一种应用于光纤延时系统中实现光纤延时精密测量的新方法,用以提高光纤延时测量的精度和准确性.该方法以1064 nm激光调制信号作为光源,通过测量回波信号的幅值和相位信息得到被测通道的频率响应,采用快速傅里叶逆变换得到被测目标的延时信息,实现光纤延时测量.本文通过理论分析和延时测量实验对频域反射法与传统的时域测量方法进行对比,使用频域反射法在调制频率范围10—200 MHz,采样频率间隔0.5 MHz的实验条件下,实现了3.3 ps延时测量分辨率,并证明了该方法具有比时域方法更高的测量精度,测量结果的准确性更好.     

基于FPGA的高分辨率数字时间转换器

针对全固态直线变压器驱动源（LTD）中大规模开关同步触发的需求,基于游标法和预相移技术设计了一种全新的双通道同步高分辨率数字时间转换器（DTC）。在原有游标DTC的基础上提前计算不同生成脉冲相位重合位置的关系,通过相位移动和相位检测使时钟信号提前满足相位关系,以实现同时触发多个不同宽度脉冲信号的目的。详细阐述了DTC的实现原理和电路设计模块,并对其进行了仿真和现场可编程门阵列（FPGA）实现,同时对实现结果进行测试、分析和讨论。在Xilinx ARTIX-7 FPGA开发板上实现了第一个脉冲信号的分辨率为0.85 ps,微分非线性（DNL）和积分非线性（INL）分别为-1.255～1.166 LSB和-7.33～7.05 LSB。第二个脉冲信号分辨率为17.113 1 ps, DNL和INL分别为-0.0987～0.105 LSB和-0.717～0.735 LSB,且在0～80℃的环境温度中依旧可以保证DTC的性能。结果表明此DTC具有实现简单、成本低,性能高效等优点。     

Visualization of aerodynamic noise source around a rotating fan blade

The purpose of this study is to understand the aerodynamic noise source distribution around a rotating fan blade by measuring the noise signal and velocity field around the blade. The local noise-level distribution over the fan blade is measured by microphone arrays, and the flow field is visualized by smoke and phase-averaged PIV measurement. The noise source distribution is examined by cross-correlation analysis between noise signal and velocity fluctuation. It is found that the noise source is located near the rotating fan blade, especially around leading and trailing edges. The separation and reattachment of flow are observed near the leading edge, and the tip vortices and vortex shedding are found near the trailing edge. The cross-correlation distribution of the noise signal and the radial velocity fluctuation shows large magnitude in the correlated regions, which indicates the noise generation by the formation of vortex structure around the blade.     

8×8APD阵列激光三维成像接收机研制

为了实现对目标的无扫描阵列激光三维成像并研究系统参数对三维成像距离分辨率的影响,研制了8×8 pixel激光三维成像接收机。接收机采用线性模式APD阵列,设计了模拟信号放大、阈值处理将回波光信号转换为数字信号后,利用FPGA设计实现64通道高精度阵列计时系统,实现了对目标的无扫描实时三维成像功能。首先对设计完成的三维成像接收机组成及成像原理进行了介绍,对三维成像接收机中APD探测器阵列信号的模拟处理和数字处理流程和实现方式进行了说明。随后分别对三维成像的核心FPGA计时系统及探测器整体进行了电子学测试和实验测试。测试结果表明,FPGA计时子系统的时间分辨率优于140 ps,三维成像系统整体距离分辨率在0.2 m左右。最后对分辨率的误差进行了分析,结果表明,激光回波强度波动是影响此接收机距离分辨率的最主要因素。     

Background-free measurement of time behaviour of an individual picosecond laser pulse

A background-free measurement of an individual pulse of a passively mode-locked Nd: glass laser during one laser shot has been performed using a crystal of LiIO₃. The method is based on the non-collinearly generated second harmonic intensity spatial distribution measurement. The time resolution was better than 0.1 ps. The method can be successfully used for picosecond pulse measurement of any laser source over a wide wavelength region.