基于连续晶体PET探测器模块电子学设计

和传统的基于分割晶体PET探测器相比,基于连续晶体的PET探测器具有设计结构简单、能量分辨率高、探测器效率高以及低造价等优点,近年来得到广泛的研究。基于连续晶体PET探测器的最大难点是要用探测器获得闪烁光分布,进而通过作用点定位算法计算γ光子的作用位置。探测器模块电子学需要读出和获取闪烁光的分布,因而电子学变得相对复杂。论文针对自行建立的基于连续LYSO晶体和神经网络定位算法的PET探测器模块的信号读出和数据获取的要求,设计和实现了64通道数据读出和获取电子学系统。该系统采用8片8通道、50 Mbps、串行输出、12 bit ADC对每个通道进行数字化,从海量的核事例中遴选出有效的核事例,在FPGA内实现数据打包、定时符合、基线恢复等功能。经过测试,电路各通道噪声低,增益一致性好。整个电子学系统结构紧凑、性能优良,适合基于连续晶体PET探测器的相关实验研究和应用研究。     

基于SiPM的乳腺专用PET探测模块研制与评价

基于单点型硅光电倍增管(Si PM)与LYSO闪烁晶体,研制了一种新型乳腺专用PET探测模块,并对其性能进行研究。该探测模块采用28×28根1.9 mm×1.9 mm×15 mm的LYSO晶体组成阵列,与8×8个单点型Si PM组成的阵列通过光导耦合,所产生的脉冲信号分别经过模拟、定时电路处理后送入高速采样电路完成信号处理。该探测模块能够实现1.9 mm位置分辨,12.73%平均能量分辨以及2.66 ns双探头符合时间分辨,具有较好的分辨性能,能够满足乳腺专用PET成像的设计需求。     

同步辐射丝扫描连续采样测量系统设计

为提高同步辐射丝扫描探测器的测量分辨率,设计了连续采样测量系统。该系统采用了扫描丝匀速运动、电子学连续采样的新工作方式,可获得更好的分辨率,提高采样率与降低扫描速度可提高光束中心位置的测量分辨率,降低扫描速度可提高光斑大小的测量分辨率,并可根据实验结果方便地确定特定分辨率要求下的采样率和扫描速度等参数的取值,对丝扫描的设计和使用提供了极大的便利。     

乳腺影像学专用PET探测器模块设计

为进一步提升乳腺影像学专用PET系统的空间位置分辨率,基于LYSO晶体与位置灵敏光电倍增管耦合,设计了一种专用LYSO-PET探测器模块。探测模块由12×12根1.5 mm×1.5 mm×10 mm LYSO晶体条阵列与PS-PMT耦合组成,通过PXI 8501采集系统,获取入射粒子的2D泛场图像、能量信息及位置信息。该探测模块平均位置分辨率可达0.22 mm(本征)和0.55 mm(²²Na探测条件下);平均能量分辨率为22.4%(²²Na探测条件下)。双探头PET系统FOV中心²²Na点源轴向空间分辨率可达1.13 mm。探测器模块已基本满足位置分辨率要求,为实现亚毫米乳腺影像学专用PET系统提供了硬件支持。     

乳腺专用PET符合处理电子学系统的研制

中国科学院高能物理研究所研制了1台具有自主知识产权的乳腺专用正电子发射断层扫描仪。本工作从硬件架构和软件逻辑功能两方面对该样机的符合处理系统的研制进行介绍。在本设计中,符合处理系统采用FPGA高速数据接口和光纤互连技术获取前端连续采样板的预处理数据,然后采用符合时间窗的方法对挑选出的非零数据进行符合处理,最后通过千兆以太网将符合数据传给后端计算机进行重建。整个系统由局域控制总线进行控制。测试结果表明,符合处理系统的设计功能正确,性能优良。     

乳腺专用PET中数据传输系统的设计

介绍了一种基于FPGA的千兆位以太网数据传输系统的设计,大大提高了数据传输速度和可靠性,具有模块化程度高、使用简单等特点.它实现了超过950 Mbps的数据传输,已经成功应用在乳腺专用PET(Positron Emission Mammography,PEM)系统之中.     

PET数据采集系统中数据对齐时序控制的设计

对PET(Positron Emission Tomography)数据采集系统中数据传输时序的不确定性进行了深入的分析,并提出了一种基于FPGA的解决方案,对核事例数据中各种数字化信息进行严格的时序控制,提高了符合处理的可靠性,提升了整个系统的性能.此设计方案已经成功应用于乳腺专用PET系统.     

PEM系统中可控时钟电路设计的优化

介绍了为乳腺专用正电子发射断层扫描仪PEM(Positron Emission Mammography)电子学数据获取(Data Acquisition,DAQ)系统提供稳定、可靠、抗干扰的高精度同步时钟的电路,它采用了基于单片机和高精度时钟产生芯片的电路设计方法,可以得到多路可控时钟信号.设计中采用差分传输,大大降低...     

GEM探测器读出电子学ADC采样系统设计

本文简要介绍了GEM探测器读出电子学ADC采样系统设计与测试。该系统包括模数变换模块、数据汇总模块和后端数据接收模块三部分。本文详细介绍了模数变换模块硬件电路设计、FPGA逻辑设计、光纤数据传输设计以及ADC采样芯片的测试方法。经过测试,该系统实现了8通道数据实时采集、传输、存储及显示功能。     

用于新型塑料闪烁体阵列探测器的多通道前端读出电子学设计

介绍一种用于新型塑料闪烁体阵列探测器系统的前端读出电子学（FEE）的设计与实现,该前端读出电子学主要基于电荷测量专用的集成电路（ASIC）芯片和现场可编程逻辑门阵列（FPGA）研制,可实现对多路探测器信号的采集、处理、筛选、打包,并通过LVDS差分接口上传到后端的数据获取系统（DAQ）。同时,该电路设有板载线性标定电路,可实现对各通道电子学性能刻度,设有电源电流、关键芯片及电路温度实时监控等电路,使电路具有较完善的功能和较强的自我保护能力。     

Development of readout electronics for bunch arrival-time monitor system at SXFEL

A bunch arrival-time monitor(BAM) system,based on electro-optical intensity modulation scheme, is under study at Shanghai Soft X-ray Free Electron Laser.The aim of the study is to achieve high-precision time measurement for minimizing bunch fluctuations. A readout electronics is developed to fulfill the requirements of the BAM system. The readout electronics is mainly composed of a signal conditioning circuit, field-programmable gate array(FPGA), mezzanine card(FMC150), and powerful FPGA carrier board. The signal conditioning circuit converts the laser pulses into electrical pulse signals using a photodiode. Thereafter, it performs splitting and low-noise amplification to achieve the best voltage sampling performance of the dual-channel analog-to-digital converter(ADC) in FMC150. The FMC150 ADC daughter card includes a 14-bit 250 Msps dual-channel high-speed ADC,a clock configuration, and a management module. The powerful FPGA carrier board is a commercial high-performance Xilinx Kintex-7 FPGA evaluation board. To achieve clock and data alignment for ADC data capture at a high sampling rate, we used ISERDES, IDELAY, and dedicated carry-in resources in the Kintex-7 FPGA. This paper presents a detailed development of the readout electronics in the BAM system and its performance.     

Development of Bunch-by-bunch Beam Position Measurement Electronics for High Energy Photon Source

A bunch-by-bunch beam position measurement (BPM) electronics for High Energy Photon Source (HEPS) storage ring was designed. The hardware of electronics consists of analog signal acquisition board and digital signal processing board. The software consists of underlying firmware and application software. The sampling frequency is 500 MHz, and the bandwidth is 1 GHz. The electronics digitizes four analog signals from BPM probe of storage ring, and obtains the amplitude of beam signal. ZYNQ chip was used to process the beam data and calculate the position of each bunch. Electronics test results in the laboratory is that the nonlinearity of ADC channels is less than 1% when the peak-to-peak value of input signal is less than 1.8 V, and spurious-free dynamic range is about 60 dB. When the sensitivity coefficient is 8.26 mm, the beam position resolution is less than 10 μm. The test results meet the needs of HEPS.     

高能同步辐射光源逐束团束流位置测量电子学研制

基于高能同步辐射光源（HEPS）储存环,研制了一套逐束团束流位置测量（BPM）电子学系统,电子学的硬件部分由模拟信号采集板卡和数字信号处理板卡组成,软件部分由底层固件和顶层应用软件组成。系统的采样频率为500 MHz,带宽为1 GHz,对来自储存环BPM探头的4路模拟信号进行数字化,得到束团幅度数据,利用ZYNQ芯片计算出每个束团在真空管道中的位置。逐束团BPM电子学在实验室的测试结果为：输入信号峰峰值小于1.8 V时ADC通道非线性度小于1%,无杂散动态范围约60 dB,灵敏度系数取8.26 mm时位置分辨率优于10 μm,测试结果满足HEPS逐束团BPM的需求。     

Design of FPGA based high-speed data acquisition and real-time data processing system on J-TEXT tokamak

Tokamak experiment requires high-speed data acquisition and processing systems. In traditional data acquisition system, the sampling rate, channel numbers and processing speed are limited by bus throughput and CPU speed. This paper presents a data acquisition and processing system based on FPGA. The data can be processed in real-time before it is passed to the CPU. It provides processing ability for more channels with higher sampling rates than the traditional data acquisition system while ensuring deterministic real-time performance. A working prototype is developed for the newly built polarimeter–interferometer diagnostic system on the Joint Texas Experimental Tokamak (J-TEXT). It provides 16 channels with 120 MHz maximum sampling rate and 16 bit resolution. The onboard FPGA is able to calculate the plasma electron density and Faraday rotation angel. A RAID 5 storage device is adopted providing 700 MB/s read–write speed to buffer the data to the hard disk continuously for better performance.     

DBPM signal processing with field programmable gate arrays

DBPM system performance is determined by the design and implementation of beam position signal processing algorithm.In order to develop the system,a beam position signal processing algorithm is implemented on FPGA.The hardware is a PMC board ICS-1554A-002(GE Corp.)with FPGA chip XC5VSX95T.This paper adopts quadrature frequency mixing to down convert high frequency signal to base.Different from conventional method,the mixing is implemented by CORDIC algorithm.The algorithm theory and implementation details are discussed in this paper.As the board contains no front end gain controller,this paper introduces a published patent-pending technique that has been adopted to realize the function in digital logic.The whole design is implemented with VHDL language. An on-line evaluation has been carried on SSRF(Shanghai Synchrotron Radiation Facility)storage ring.Results indicate that the system turn-by-turn data can measure the real beam movement accurately,and system resolution is 1.1μm.     

Development of sulfonated FEP-Nafion hybrid proton exchange membranes for PEFC

The performance of polymer electrolyte fuel cell (PEFC) is affected by an interfacial property between a proton exchange membrane (PEM) and electrodes. Thus, to develop a well-laminated membrane electrode assembly (MEA), a hybrid PEM (FN) was fabricated by mixing a radiation grafted membrane (sulfonated FEP) with ionomer (Nafion^® dispersion) which is applied to coat the interface of the PEM and electrodes.The obtained FN, sulfonated FEP and Nafion^®112 were characterized in terms of water uptake, ion exchange capacity (IEC), polarization performance and electrochemical impedance. FN showed high IEC and water uptake, which would induce the highest ionic conductivity (IC) among tested PEMs. In terms of FN, the interface between the PEM and electrodes should have been improved because FN showed the lowest charge transfer resistance than other tested PEMs. The high IC and improved interface between the PEM and electrodes resulted in the best cell performance of FN in tested PEMs.     

高计数率气体探测器读出电子学原型机研制

研制一套可用于高计数率气体探测器的读出电子学原型机系统,包括前端板、数据采集板和上位机。前端板采用一款先进的前端读出专用集成电路(ASIC)芯片实现对探测器信号的测量和模数转换;数据采集板利用现场可编程门阵列（FPGA）实现对数据的分析、处理和传输;上位机实现控制指令发送、PC端数据接收及存储等。在22~99 fC的输入范围内,原型机各通道积分非线性均好于024%;联合探测器使用55Fe放射源测试,结果好于相同条件下的商用电子学。可满足20 kHz计数率下GEM TPC探测器的读出需求。     

Development of function-graded proton exchange membrane for PEFC using heavy ion beam irradiation

The graded energy deposition of heavy ion beam irradiation to polymeric materials was utilized to synthesize a novel proton exchange membrane (PEM) with the graded density of sulfonic acid groups toward the thickness direction. Stacked Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were irradiated by Xe⁵⁴⁺ ion beam with the energy of 6 MeV/u under a vacuum condition. The induced trapped radicals by the irradiation were measured by electron spin resonance (ESR) spectroscopy. Irradiated films were grafted with styrene monomer and then sulfonated. X-ray photo-electron spectroscopy (XPS) spectra showed that the densities of sulfonic acid groups were controlled for injection “Surface” and transmit “Back” sides of the fabricated PEM. The membrane electrode assembly (MEA) fabricated by the function-graded PEM showed improved fuel cell performance in terms of voltage stability. It was expected that the function-graded PEM could control the graded concentration of sulfonic acid groups in PEM.     

辐射接枝高分子电解膜的制备、表征及其在燃料电池中的应用

高分子电解膜是高分子燃料电池的关键材料之一。担当着阴阳极反应原料的隔离及离子电导的功能,其性能决定着燃料电池的性能、成本及应用前景。辐射接枝电解膜由氟化的高分子骨架及磺化的接枝高分子链构成。前者赋予电解膜必要的强度、尺寸稳定性及低气体透过性,后者赋予其质子电导功能。综述了基材、单体及交联剂的筛选、合成工艺的调整等与辐射接枝电解膜的性能关系。