CSNS多功能反射谱仪主探测器读出电子学系统研制

为满足中国散裂中子源（CSNS）多功能反射谱仪（MR）主探测器高气压³He多丝正比室探测器（MWPC）的需求,研制了专用的读出电子学系统。该系统主要由核心前放板和触发扇出板构成,其中以前放板为核心,采用了6块前放板实现探测器142路模拟信号的数字化,并通过判选机制甄别中子信息,将有效中子事例打包发送给后端,触发扇出板提供同一时刻到达的T0信号和触发信号,以确保数据的对齐。读出电子学系统分别在实验室和束流条件下,进行了相关指标测试,测试结果表明性能优于设计要求。目前MWPC探测器已经成功安装到MR谱仪现场,并且已经开始稳定运行。     

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...     

中国散裂中子源4K低温恒温器研制及测试

中国散裂中子源(CSNS)中子谱仪的运行离不开低温设备提供的低温样品环境，考虑到中子散射的特殊性，样品处不能放置温度计，所以需要对样品温度进行校核。校核结果显示部分低温恒温器样品座测点温度与实际样品温度存在差值。针对该问题，对样品区域进行热工分析及建模求解后，给出了样品区匀温恒温器设计方案。据此CSNS样品环境组设计组装了一套匀温恒温器，该恒温器的温度测试结果显示，4～300 K之间样品温度与测点温度差值在±3 K之内，另外也对300～800 K之间减少样品温差的方案进行了计算和测试。样品区匀温恒温器的研制满足了CSNS对样品测温准确的要求，也对类似设备的匀温方案提供了一定参考，有助于大科学装置设备的国产化。     

ALICE实验中光子谱仪的触发选判机制的模拟研究

对ALICE实验光子谱仪的触发选判机制进行了模拟研究, 内容包括: 1) 对光子谱仪的能量重建性能进行了研究, 通过计算机模拟检验光子谱仪探测器对大横动量范围的入射粒子的能量重建性能; 2) 对光子谱仪探测器的事件触发效率进行了研究, 通过计算机模拟分析触发阈值的选取并计算触发效率; 3) 对光子谱仪探测器的事件触发频率进行了研究, 通过计算机模拟对p-p和Pb-Pb两种碰撞模式下的触发频率分别进行了估算和讨论.     

CSNS多功能反射谱仪3He管探测器数据获取系统设计

作为中国散裂中子源(CSNS)工程中多功能反射(RM)谱仪一部分的3He管探测器数据获取系统不仅要具有基本的读取和处理数据的功能,还需要协调配合谱仪的整体运行,稳定可靠地与其它异构系统进行交互。通过规划数据获取的整体框架,采取有效的方式优化关键部分,另外挑选合适的三方软件包整合到数据获取系统中,达到了该系统操作方便灵活、功能完善、运行稳定可靠并且高效率,满足谱仪实验需求的目的。包括数据获取系统在内的多功能反射谱仪顺利通过了国家验收,目前这套数据获取系统已经成功应用在多功能反射谱仪的束流实验中。     

R值扫描实验中触发效率的测量

介绍了北京正负电子对撞机(BEPC)/北京谱仪(BES)R值扫描实验中触发效率的测量方法,BES触发判选系统触发条件表的设置,给出了R值测量实验期间各触发条件、触发道以及不同类型事例的触发效率.     

基于PCI总线的全功能数字化频率源

介绍了一种适用于核磁共振谱仪的全功能数字化频率源,它能够直接输出0~135 MHz的信号,且信号的频率、相位和幅度可以快速切换. 该频率源设计成基于计算机PCI总线的板卡结构,可以直接插入PC机的PCI插槽内. 在板上包含了128 k用于预先存储波形数据的静态内存,外部设备提供触发信号即可输出所需的射频波形. 该频率源具有结构简单,性能良好,成本低廉等特点,特别适用于较低设计成本的核磁共振谱仪.     

中国散裂中子源小角散射谱仪

作为中国散裂中子源(CSNS)首批建设的三套谱仪之一,小角散射谱仪用于探测物质体系在1~100 nm尺度内的微观和介观结构。它的实验应用范围将涵盖化学、物理、生物、材料、地质等广泛学科,服务于国家能源、环境、生物和新材料等诸多高科技研发领域。中国散裂中子源小角散射谱仪建成后,能为图1所示例的诸多科学探索与技术研发工作,提供必需的实验方法及其技术手段。     

HC-4型固体多核宽线CW-NMR波谱仪

设计和研制了一台用于检测固体中NMR宽谱线、型号为HC-4的CW-NMR波谱仪.谱仪由APPLE-Ⅱ微型计算机控制扫描、信号累加和数据处理.配备了自制的交叉线圈型和魔T型NMR探头和高温(1300K)探头,使谱仪具有较高的检测灵敏度和较强的测量功能,适用于检测固体中多种非质子核的NMR宽谱线及动态NMR测量.本文简要介绍该谱仪的基本结构、系统各部分的技术性能和测量应用的具体实例.     

北京谱仪顶点探测器触发效率的研究

模拟了北京谱仪(BESⅡ)顶点探测器的触发判选系统,发现对于某些带次级顶点的衰变道,其顶点探测器触发效率较低.并由此对BESⅡ中与效率相关的物理过程作了讨论,给相应的触发设计者提供参考.     

L0 trigger unit prototype for BM@N setup

The BM@N facility is a fixed target experiment based on heavy ion beams of the Nuclotron-M accelerator. The aim of the BM@N is to study nucleus – nucleus collisions at energies up to 4.5 GeV per nucleon. A level 0 trigger processor unit (Trigger L0 unit, T0U) for the BM@N deuterons and carbon ions at Run’2015 has been developed. The T0U is used to generate a BM@N zero level trigger and a TOF detector precise start.T0U generates trigger signal based on beam line and target area detector signals. This module also provides both control and monitoring of the detector front-end electronics power supplies. This article presents a concept, characteristics and test results of the T0U module during the Run 2015.     

Z箍缩诊断系统的触发和抗干扰技术

通过对时间关联信号的筛选、转换和延时等方法建立了用于8 MA脉冲功率装置上Z箍缩实验中诊断设备的触发网络,其输出触发信号与被测X射线之间的时间抖动小于2 ns,满足了纳秒级的诊断时间同步要求。采用屏蔽、接地等有效措施基本消除了放电产生的强电磁环境以及其它杂散信号对触发线缆和诊断设备的干扰,保证了诊断设备的正常工作和实验数据的质量。     

Accuracy and effectiveness of self-gating signals in free-breathing three-dimensional cardiac cine magnetic resonance imaging

Conventional multiple breath-hold two-dimensional(2D) balanced steady-state free precession(SSFP) presents many difficulties in cardiac cine magnetic resonance imaging(MRI). Recently, a self-gated free-breathing three-dimensional(3D) SSFP technique has been proposed as an alternative in many studies. However, the accuracy and effectiveness of selfgating signals have been barely studied before. Since self-gating signals are crucially important in image reconstruction, a systematic study of self-gating signals and comparison with external monitored signals are needed.Previously developed self-gated free-breathing 3D SSFP techniques are used on twenty-eight healthy volunteers. Both electrocardiographic(ECG) and respiratory bellow signals are also acquired during the scan as external signals. Self-gating signal and external signal are compared by trigger and gating window. Gating window is proposed to evaluate the accuracy and effectiveness of respiratory self-gating signal. Relative deviation of the trigger and root-mean-square-deviation of the cycle duration are calculated. A two-tailed paired t-test is used to identify the difference between self-gating and external signals. A Wilcoxon signed rank test is used to identify the difference between peak and valley self-gating triggers.The results demonstrate an excellent correlation(P = 0, R 0.99) between self-gating and external triggers. Wilcoxon signed rank test shows that there is no significant difference between peak and valley self-gating triggers for both cardiac(H = 0, P 0.10) and respiratory(H = 0, P 0.44) motions. The difference between self-gating and externally monitored signals is not significant(two-tailed paired-sample t-test: H = 0, P 0.90).The self-gating signals could demonstrate cardiac and respiratory motion accurately and effectively as ECG and respiratory bellow. The difference between the two methods is not significant and can be explained. Furthermore, few ECG trigger errors appear in some subjects while these errors are not found in self-gating signals.     

宽带磁共振T/R开关的设计与实现

磁共振系统中的发射/接收（transmit/receive,T/R）开关用于收发通路的切换,要求在隔离大功率信号的同时具有较小的插入损耗;另外,在宽带磁共振谱仪中,一般的窄带T/R开关也不再适用.本文基于PIN（positive-intrinsic-negative）二极管设计了工作频率为10~100 MHz的宽带磁共振T/R开关.通过减小电平跳变、优化开关过冲和解决二极管被动导通等问题,获得了插入损耗小于1 dB、大功率信号隔离度大于75 dB、开关时间1 μs的整体性能.用本文设计的宽带T/R开关替代一般探头中的窄带T/R开关,在0.5 T核磁共振（NMR）波谱仪上测得了氢核和氟核两个不同频率的磁共振信号,验证了宽带T/R开关的宽带性能.     

可见/近红外实时成像光谱仪控制系统设计

针对高光谱成像需求,设计了一套可见/近红外实时成像光谱仪.光谱仪基于声光可调谐滤波器(Acousto-Optic Tunable Filter,AOTF)分光器件进行设计,光谱带宽为1.3μm,其中可见光相机工作在400～1000 nm波段,近红外相机工作在1000～1700 nm波段.光谱仪控制系统以现场可编程门阵列...     

基于TTL数字电路控制的高压脉冲源

给出了一种基于TTL数字电路作为高压脉冲源触发控制单元的设计原理和方法。介绍了高压脉冲源的工作原理,设计了一台脉冲输出幅度5 kV、脉冲宽度大于200 s及脉冲前沿小于30 ns的高压脉冲源。将触发控制单元和前级开关金属氧化物半导体场效应管（MOSFET）组合成一体,控制后级气体高压开关管放电输出高压脉冲信号。实验结果验证了所采用的设计原理及方法的可行性,给出了单次触发情况下的实验结果。     

基于TTL数字电路控制的高压脉冲源

给出了一种基于TTL数字电路作为高压脉冲源触发控制单元的设计原理和方法。介绍了高压脉冲源的工作原理,设计了一台脉冲输出幅度5 kV、脉冲宽度大于200 s及脉冲前沿小于30 ns的高压脉冲源。将触发控制单元和前级开关金属氧化物半导体场效应管（MOSFET）组合成一体,控制后级气体高压开关管放电输出高压脉冲信号。实验结果验证了所采用的设计原理及方法的可行性,给出了单次触发情况下的实验结果。     

An adaptive correlation ratemeter: a new method for Doppler fetal heart rate measurements

For use in a cardiotocograph, ultrasound Doppler fetal signals have been thought to provide merely a limited reliability of the fetal heart rate record because of the difficulty of signal processing to obtain a consistent trigger, although the signal itself is easy to obtain with an excellent signal-to-noise ratio.However, the authors have developed a unique signal processing system using a correlation technique with an automatic adaptation algorithm, which solved almost all of the difficulties associated with the old Doppler cardiotocograph and showed that the ultrasound Doppler fetal signal can also provide heart rate records compatible to that obtained by a fetal ECG system.The authors are sure that their method is a most promising one in the coming age of microprocessor-oriented instrumentation.